ISSN 1000-0526
CN 11-2282/P
CN 11-2282/P
Volume 52,2026 Issue 6
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- The Future Projections of Extreme Weather, Climate and Water Events and Strategic Responses
- A Review of Downburst Genesis Mechanism and Warning
- The Pattern Structure and Thermodynamic and Dynamic Processes of Severe Storms Associated with Linear Convective Gales
- Analysis on Extremity and Characteristics of the “21·7” Severe Torrential Rain in Henan Province
- Diagnostic Analysis on Water Vapor and Jet Characteristics of the July 2021 Severe Torrential Rain in Henan Province
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2026,52(6):641-656, DOI: 10.7519/j.issn.1000-0526.2026.051303
Abstract:
From 23 to 29 July 2025, extreme torrential rain occurred in Beijing. Based on multi-source observation data, ERA5 reanalysis data, RISE and RMAPS-NOW high-resolution grid analysis data, this paper analyzes the characteristics of rainfall stages, the spatio-temporal features and causes of this event. The results show that the July 2025 extreme torrential rain occurred under a stable circulation background where the subtropical high was significantly westward and northward and stronger than usual, with active tropical systems on its southern side. The lower atmosphere had warm anomalies, with a positive water vapor flux anomaly at 925 hPa and a significantly enhanced water vapor convergence zone in northern and eastern Beijing, creating conditions of high temperature, high humidity and high CAPE. This rainfall event was featured with long duration, much more accumulated precipitation, nocturnal occurrence, localization and extremity. According to the daily evolution of precipitation, the whole event is divided into four stages, corresponding to the swing of the 588 dagpm contour position of the subtropical high. Extreme torrential rain occurred in Stage 2 and Stage 3, concentrated in the northern mountainous areas of Beijing, featuring a “weak overall but strong locally” pattern, and also accompanied by extreme short-time heavy rainfall. The focus analysis on this two stages indicates that, the radar echoes in Stage 2 showed obvious backward triggering and “train effect” characteristics, lasting 4-5 h with torrential rain occurring at altitudes of 200-600 m. However, in Stage 3 there were continuous generation and dissipation of convection within banded echoes, lasting more than ten hours, with the occurrence of torrential rain mainly below the 300 m altitude. Further analysis on the causes shows that both Stage 2 and Stage 3 had favorable dynamic and topographic conditions, including the exit area of the mesoscale low-level jet, the convergence of southerly and southeasterly winds in the boundary layer, as well as the horn-shaped terrain and windward slopes of the mountains. The difference between two stages is that it was warm-sector torrential rain in the Stage 2, during which the exit area of southern boundary-layer jet was in the northern shallow mountains, the low-level convergence along the mountains was conducive to continuous triggering of convection, and the “train effect” caused the occurrence of extreme torrential rain. While the Stage 3 was influenced by a weak cold air and was related to dynamic convergence on the southern side of a shear line and a mesoscale low vortex. Accordingly, the conceptual model of the July 2025 extreme torrential rain is established.
From 23 to 29 July 2025, extreme torrential rain occurred in Beijing. Based on multi-source observation data, ERA5 reanalysis data, RISE and RMAPS-NOW high-resolution grid analysis data, this paper analyzes the characteristics of rainfall stages, the spatio-temporal features and causes of this event. The results show that the July 2025 extreme torrential rain occurred under a stable circulation background where the subtropical high was significantly westward and northward and stronger than usual, with active tropical systems on its southern side. The lower atmosphere had warm anomalies, with a positive water vapor flux anomaly at 925 hPa and a significantly enhanced water vapor convergence zone in northern and eastern Beijing, creating conditions of high temperature, high humidity and high CAPE. This rainfall event was featured with long duration, much more accumulated precipitation, nocturnal occurrence, localization and extremity. According to the daily evolution of precipitation, the whole event is divided into four stages, corresponding to the swing of the 588 dagpm contour position of the subtropical high. Extreme torrential rain occurred in Stage 2 and Stage 3, concentrated in the northern mountainous areas of Beijing, featuring a “weak overall but strong locally” pattern, and also accompanied by extreme short-time heavy rainfall. The focus analysis on this two stages indicates that, the radar echoes in Stage 2 showed obvious backward triggering and “train effect” characteristics, lasting 4-5 h with torrential rain occurring at altitudes of 200-600 m. However, in Stage 3 there were continuous generation and dissipation of convection within banded echoes, lasting more than ten hours, with the occurrence of torrential rain mainly below the 300 m altitude. Further analysis on the causes shows that both Stage 2 and Stage 3 had favorable dynamic and topographic conditions, including the exit area of the mesoscale low-level jet, the convergence of southerly and southeasterly winds in the boundary layer, as well as the horn-shaped terrain and windward slopes of the mountains. The difference between two stages is that it was warm-sector torrential rain in the Stage 2, during which the exit area of southern boundary-layer jet was in the northern shallow mountains, the low-level convergence along the mountains was conducive to continuous triggering of convection, and the “train effect” caused the occurrence of extreme torrential rain. While the Stage 3 was influenced by a weak cold air and was related to dynamic convergence on the southern side of a shear line and a mesoscale low vortex. Accordingly, the conceptual model of the July 2025 extreme torrential rain is established.
2026,52(6):657-672, DOI: 10.7519/j.issn.1000-0526.2026.031101
Abstract:
With multi-source observations and ERA5 reanalysis data, this paper systematically analyzes an extreme torrential rain event that occurred in North China in late July 2025, and reveals the diversity in the initiation, organization and propagation mechanisms of mesoscale convective systems during three days with extreme rainfall (24, 25 and 27 July) under a similar large-scale warm-sector background. Besides, the synoptic causes for the extreme torrential rain are investigated. The results show that this extreme rainfall event was characterized by significant extremity with heavy rainfall intensity and large accumulated precipitation amount. The multiple extreme precipitation centers within the southern warm-sector rainband posed big challenges to the forecasting operation. On 24 July, the convection initiated at the foothills, and the extreme rainfall was dominated by a “train effect” from backward-propagating and band-shaped convection, which resulted in the most widespread rainfall area spanning mountains, foothills and plains. On 25 July, the convection originated in mountains, and the extreme rainfall was associated with a quasi-stationary system, leading to the localized precipitation. On July 27, the convection mostly initiated in plains and intensified after moving to the foothills. The extreme rainfall was related to the “train effect” from line-shaped convections, and the heavy precipitation occurred mainly in mountainous areas. On 24 July, the synoptic scale forcing was most significant. The strong and deep low-level jet (LLJ), coupled with orographic lifting and sustained moisture transport, played a key role in the initiation and back-propagation of the convection. The convergent frontal zone formed by the outflow of the cold pool had a very important role in organizing the rainfall system and its expansion into plains. On 25 July, under the control of the subtropical high, a weaker and shallower LLJ restricted the downstream propagation of the convective system, making orographic lifting the dominant mechanism for the triggering and enhancement of heavy precipitation. This was accompanied by a mesocyclone-like structure that produced the heaviest local hourly rainfall. On 27 July, under the weakest synoptic scale forcing, the convection was triggered by boundary layer easterly airflow and low-level weak convergence line. The mesoscale front area formed by the cold pool in mountainous areas and the warm ridge in plains provided favorable conditions for backward propagation. Moreover, the convergence and lifting of the southwest airflow in front of the terrain built powerful dynamic conditions for the significant intensification of the convection moving from plains into foothills.
With multi-source observations and ERA5 reanalysis data, this paper systematically analyzes an extreme torrential rain event that occurred in North China in late July 2025, and reveals the diversity in the initiation, organization and propagation mechanisms of mesoscale convective systems during three days with extreme rainfall (24, 25 and 27 July) under a similar large-scale warm-sector background. Besides, the synoptic causes for the extreme torrential rain are investigated. The results show that this extreme rainfall event was characterized by significant extremity with heavy rainfall intensity and large accumulated precipitation amount. The multiple extreme precipitation centers within the southern warm-sector rainband posed big challenges to the forecasting operation. On 24 July, the convection initiated at the foothills, and the extreme rainfall was dominated by a “train effect” from backward-propagating and band-shaped convection, which resulted in the most widespread rainfall area spanning mountains, foothills and plains. On 25 July, the convection originated in mountains, and the extreme rainfall was associated with a quasi-stationary system, leading to the localized precipitation. On July 27, the convection mostly initiated in plains and intensified after moving to the foothills. The extreme rainfall was related to the “train effect” from line-shaped convections, and the heavy precipitation occurred mainly in mountainous areas. On 24 July, the synoptic scale forcing was most significant. The strong and deep low-level jet (LLJ), coupled with orographic lifting and sustained moisture transport, played a key role in the initiation and back-propagation of the convection. The convergent frontal zone formed by the outflow of the cold pool had a very important role in organizing the rainfall system and its expansion into plains. On 25 July, under the control of the subtropical high, a weaker and shallower LLJ restricted the downstream propagation of the convective system, making orographic lifting the dominant mechanism for the triggering and enhancement of heavy precipitation. This was accompanied by a mesocyclone-like structure that produced the heaviest local hourly rainfall. On 27 July, under the weakest synoptic scale forcing, the convection was triggered by boundary layer easterly airflow and low-level weak convergence line. The mesoscale front area formed by the cold pool in mountainous areas and the warm ridge in plains provided favorable conditions for backward propagation. Moreover, the convergence and lifting of the southwest airflow in front of the terrain built powerful dynamic conditions for the significant intensification of the convection moving from plains into foothills.
2026,52(6):673-685, DOI: 10.7519/j.issn.1000-0526.2026.051301
Abstract:
Based on the surface precipitation data and the ERA5 reanalysis data, the torrential rain that occurred in North China from 23 to 29 July 2025 is investigated from the perspectives of circulation evolution and water vapor conditions. The findings reveal that the torrential rain was a across-warp type process, lasting for seven days, with the main precipitation area zonally spanning over 1000 km. Two primary rain belts were identified, located in the plateau region (secondary terrain area) and the plain region (tertiary terrain area) of North China, respectively. The anomalous large-scale circulation patterns were observed during this precipitation event. The abnormally persistent northward-shifting western Pacific subtropical high (WPSH), a stagnant westerly shortwave trough, and the shear lines generated in the lower troposphere were the key weather systems responsible for the distinct spatio-temporal distribution of precipitation compared to the past typical torrential rain events in North China. The eastward extension of the South Asian high and the westward movement of WPSH dominated the evolution of the torrential rain event and the zonal pattern of precipitation. The low-latitude weather system remained active, and the typhoons Francisco and Co-may, which emerged continuously near East China coastline, transported water vapor in a relay manner with the abnormally westward WPSH. Two water vapor transport belts and convergence zones were formed within the main precipitation area, feeding the two rain belts in the secondary and tertiary terrain regions. The water vapor budget analysis indicates that there was abundant water vapor supply during this torrential rain event, and the abnormally westward WPSH led to a southwestward transport of water vapor. Affected by the advance and retreat of the WPSH, water vapor exhibited obvious cross-topographic transport characteristics.
Based on the surface precipitation data and the ERA5 reanalysis data, the torrential rain that occurred in North China from 23 to 29 July 2025 is investigated from the perspectives of circulation evolution and water vapor conditions. The findings reveal that the torrential rain was a across-warp type process, lasting for seven days, with the main precipitation area zonally spanning over 1000 km. Two primary rain belts were identified, located in the plateau region (secondary terrain area) and the plain region (tertiary terrain area) of North China, respectively. The anomalous large-scale circulation patterns were observed during this precipitation event. The abnormally persistent northward-shifting western Pacific subtropical high (WPSH), a stagnant westerly shortwave trough, and the shear lines generated in the lower troposphere were the key weather systems responsible for the distinct spatio-temporal distribution of precipitation compared to the past typical torrential rain events in North China. The eastward extension of the South Asian high and the westward movement of WPSH dominated the evolution of the torrential rain event and the zonal pattern of precipitation. The low-latitude weather system remained active, and the typhoons Francisco and Co-may, which emerged continuously near East China coastline, transported water vapor in a relay manner with the abnormally westward WPSH. Two water vapor transport belts and convergence zones were formed within the main precipitation area, feeding the two rain belts in the secondary and tertiary terrain regions. The water vapor budget analysis indicates that there was abundant water vapor supply during this torrential rain event, and the abnormally westward WPSH led to a southwestward transport of water vapor. Affected by the advance and retreat of the WPSH, water vapor exhibited obvious cross-topographic transport characteristics.
2026,52(6):686-701, DOI: 10.7519/j.issn.1000-0526.2026.042701
Abstract:
Using refined hourly meteorological observations, radar data, and other multi-source observation data, along with ERA5 reanalysis data, this paper analyzes the characteristics and causes of the ultra-long-duration regional extreme torrential rain event that occurred in Beijing from 23 to 29 July 2025. The results indicate that this event was the longest-lasting heavy precipitation event in the past decade, and the number of stations with daily precipitation ≥50 mm and the daily maximum precipitation during the event ranked the second after the extreme torrential rain event on 30 July 2023. This event also exhibited significant nocturnal rainfall characteristics, with the maximum hourly rainfall intensity concentrated in the period from midnight to early morning hours. The areas of heavy precipitation were primarily distributed over the plains in front of the Yanshan Mountains and on the windward slopes. This torrential rain event was mainly influenced by the subtropical high system, low-latitude tropical weather systems, and mid-to-high-latitude westerly troughs. The analysis of the geopotential height anomaly field from July 23 to 28 reveals that the subtropical high was positioned more northward than usual. The tropical low-pressure system overlapped with the abnormally northward-shifted peripheral airflow of the subtropical high, forming a sustained southerly airflow that was transported northward to the Beijing Region, which provided abundant moisture for the extreme precipitation. The moisture content was significantly higher than the climatological average, with areas of high specific humidity overlapping with southerly wind anomalies. Coupled with the orographic uplift effect of the Yanshan Mountains, these factors significantly enhanced precipitation intensity. A prolonged high-humidity environment was maintained below 500 hPa throughout this event, with the average specific humidity at 925 hPa (14.3 g·kg-1), 850 hPa (12.2 g·kg-1), and 700 hPa (7.4 g·kg-1) exceeding the average values recorded in torrential rain events over the past decade (based on statistics from the Beijing Sounding Station). Under the daytime conditions of high temperature and humidity, unstable energy was accumulated. At night, the enhanced low-level jet, combined with terrain lifting, contributed to the pronounced nocturnal rainfall characteristics of this torrential rain event. The major impact systems of the extreme torrential rain over the night of 26 July could not be identified with the conventional data including ERA5 reanalysis data, but the radar imagery clearly reveals that the main impact systems of the extreme torrential rain were the low-level convergence line and the small-scale low-level jet.
Using refined hourly meteorological observations, radar data, and other multi-source observation data, along with ERA5 reanalysis data, this paper analyzes the characteristics and causes of the ultra-long-duration regional extreme torrential rain event that occurred in Beijing from 23 to 29 July 2025. The results indicate that this event was the longest-lasting heavy precipitation event in the past decade, and the number of stations with daily precipitation ≥50 mm and the daily maximum precipitation during the event ranked the second after the extreme torrential rain event on 30 July 2023. This event also exhibited significant nocturnal rainfall characteristics, with the maximum hourly rainfall intensity concentrated in the period from midnight to early morning hours. The areas of heavy precipitation were primarily distributed over the plains in front of the Yanshan Mountains and on the windward slopes. This torrential rain event was mainly influenced by the subtropical high system, low-latitude tropical weather systems, and mid-to-high-latitude westerly troughs. The analysis of the geopotential height anomaly field from July 23 to 28 reveals that the subtropical high was positioned more northward than usual. The tropical low-pressure system overlapped with the abnormally northward-shifted peripheral airflow of the subtropical high, forming a sustained southerly airflow that was transported northward to the Beijing Region, which provided abundant moisture for the extreme precipitation. The moisture content was significantly higher than the climatological average, with areas of high specific humidity overlapping with southerly wind anomalies. Coupled with the orographic uplift effect of the Yanshan Mountains, these factors significantly enhanced precipitation intensity. A prolonged high-humidity environment was maintained below 500 hPa throughout this event, with the average specific humidity at 925 hPa (14.3 g·kg-1), 850 hPa (12.2 g·kg-1), and 700 hPa (7.4 g·kg-1) exceeding the average values recorded in torrential rain events over the past decade (based on statistics from the Beijing Sounding Station). Under the daytime conditions of high temperature and humidity, unstable energy was accumulated. At night, the enhanced low-level jet, combined with terrain lifting, contributed to the pronounced nocturnal rainfall characteristics of this torrential rain event. The major impact systems of the extreme torrential rain over the night of 26 July could not be identified with the conventional data including ERA5 reanalysis data, but the radar imagery clearly reveals that the main impact systems of the extreme torrential rain were the low-level convergence line and the small-scale low-level jet.
BAO Hongjun, ZENG Sihai, WANG Jianwen, YUN Xiaobo, LIN Jian, ZHANG Bo, LI Zhijia, LUAN Chengmei, WANG Meng, XU Fengwen
2026,52(6):702-712, DOI: 10.7519/j.issn.1000-0526.2026.011301
Abstract:
In late July 2025, Chaobai River Basin experienced the most serious flood disaster since 1959. In this paper, a flood simulation and forecasting model is developed for Chaobai River Basin based on a distributed hydrological model to retrospectively analyze the characteristics of the July 2025 regional flood in this basin. The Zhangjiafen hydrometrical cross-section of the Baihe River, the Xiahui hydrometrical cross-section of the Chaohe River, and the Putaoyuan hydrometrical cross-section of the Qingshui River are taken for testing hydrological sections, and a basin flood simulation and forecasting model is developed based on GMKHM distributed hydrological model. The GMKHM model adopts hourly precipitation observation data from CMA regional meteorological stations as forcing input, introduces runoff curve numbers and topographic indices to develop a DEM-based over-storage runoff production model, and has a module of recharging deep groundwater added in the calculation of water source separation. The results show that the peak discharge simulation errors are -1.8% and -4.0% respectively for the Zhangjiafen hydrometrical cross-section of the Baihe River and the Xiahui cross-section of the Chaohe River under the GMKHM distributed hydrological model. The model determination coefficient is 0.87 for the Zhangjiafen hydrometrical cross-section and 0.89 for the Xiahui hydrometrical cross-section. For the Putaoyuan hydrometrical cross-section of the Qingshui River, the peak discharge error is 0.9% and the determination coefficient reaches 0.92. Overall, the GMKHM distributed hydrological model performs well in simulating the July 2025 flood event in the Chaobai River Basin.
In late July 2025, Chaobai River Basin experienced the most serious flood disaster since 1959. In this paper, a flood simulation and forecasting model is developed for Chaobai River Basin based on a distributed hydrological model to retrospectively analyze the characteristics of the July 2025 regional flood in this basin. The Zhangjiafen hydrometrical cross-section of the Baihe River, the Xiahui hydrometrical cross-section of the Chaohe River, and the Putaoyuan hydrometrical cross-section of the Qingshui River are taken for testing hydrological sections, and a basin flood simulation and forecasting model is developed based on GMKHM distributed hydrological model. The GMKHM model adopts hourly precipitation observation data from CMA regional meteorological stations as forcing input, introduces runoff curve numbers and topographic indices to develop a DEM-based over-storage runoff production model, and has a module of recharging deep groundwater added in the calculation of water source separation. The results show that the peak discharge simulation errors are -1.8% and -4.0% respectively for the Zhangjiafen hydrometrical cross-section of the Baihe River and the Xiahui cross-section of the Chaohe River under the GMKHM distributed hydrological model. The model determination coefficient is 0.87 for the Zhangjiafen hydrometrical cross-section and 0.89 for the Xiahui hydrometrical cross-section. For the Putaoyuan hydrometrical cross-section of the Qingshui River, the peak discharge error is 0.9% and the determination coefficient reaches 0.92. Overall, the GMKHM distributed hydrological model performs well in simulating the July 2025 flood event in the Chaobai River Basin.
2026,52(6):713-725, DOI: 10.7519/j.issn.1000-0526.2025.121901
Abstract:
Current deep learning-based QPE methods using radar reflectivity factors mostly adopt global mapping strategies, which to some extent limits the models’ ability to analyze local precipitation features. To this end, this study proposes a Dual-Branch Composite Wavelet Attention UNet (DCWA-UNet) model. The model is mainly improved from the following two aspects. Firstly, a hybrid architecture consisting of a dual-branch encoder (main branch + simplified convolutional downsampling branch) and a feature aggregation subnetwork is designed, which enables the end-to-end mapping from radar volume scan data to station precipitation intensity, thereby constructing a station-centered sample system. Secondly, a composite wavelet attention module (CWAM) is introduced to enhance the model’s representation capability for radar echoes through multi-scale feature decomposition and dynamic weight allocation. Meanwhile, a weighted mean squared error loss function is adopted to emphasize the gradient contribution of moderate-to-high precipitation. Using ground-based precipitation observation and radar observation data in the Sichuan Basin during the summers of 2019-2021, a dataset containing 4020 samples is constructed for model training and testing, and comparative experiments are conducted with deep learning models such as SimVP. The results show that DCWA-UNet achieves obvious comprehensive performance advantages under different precipitation intensities, with particularly significant improvements in critical success index (CSI) and mean absolute error (MAE) within the precipitation intensity below 30 mm·h-1. For precipitation intensities of ［5, 10) mm·h-1, the CSI of DCWA-UNet is significantly higher than that of SimVP and other comparative models, and the MAE is reduced by 4.9% compared to SimVP; for precipitation intensities of ［10, 30］ mm·h-1, the CSI is improved by 4.0% and the MAE is reduced by 4.0% compared to SimVP. Moreover, the false alarm rate is the lowest among all comparative models.
Current deep learning-based QPE methods using radar reflectivity factors mostly adopt global mapping strategies, which to some extent limits the models’ ability to analyze local precipitation features. To this end, this study proposes a Dual-Branch Composite Wavelet Attention UNet (DCWA-UNet) model. The model is mainly improved from the following two aspects. Firstly, a hybrid architecture consisting of a dual-branch encoder (main branch + simplified convolutional downsampling branch) and a feature aggregation subnetwork is designed, which enables the end-to-end mapping from radar volume scan data to station precipitation intensity, thereby constructing a station-centered sample system. Secondly, a composite wavelet attention module (CWAM) is introduced to enhance the model’s representation capability for radar echoes through multi-scale feature decomposition and dynamic weight allocation. Meanwhile, a weighted mean squared error loss function is adopted to emphasize the gradient contribution of moderate-to-high precipitation. Using ground-based precipitation observation and radar observation data in the Sichuan Basin during the summers of 2019-2021, a dataset containing 4020 samples is constructed for model training and testing, and comparative experiments are conducted with deep learning models such as SimVP. The results show that DCWA-UNet achieves obvious comprehensive performance advantages under different precipitation intensities, with particularly significant improvements in critical success index (CSI) and mean absolute error (MAE) within the precipitation intensity below 30 mm·h-1. For precipitation intensities of ［5, 10) mm·h-1, the CSI of DCWA-UNet is significantly higher than that of SimVP and other comparative models, and the MAE is reduced by 4.9% compared to SimVP; for precipitation intensities of ［10, 30］ mm·h-1, the CSI is improved by 4.0% and the MAE is reduced by 4.0% compared to SimVP. Moreover, the false alarm rate is the lowest among all comparative models.
ZHANG Zeyu, BAI Lanqiang, CAI Kanglong, HUANG Shuting, HUANG Xianxiang, YANG Lei, XU Zongheng, WANG Xiuming, ZHANG Tao, LI Cailing, CHEN Pakwai
2026,52(6):726-741, DOI: 10.7519/j.issn.1000-0526.2026.050701
Abstract:
Basic characteristics of tornadoes in China in 2024 are presented in this article based on comprehensive analysis of multi-source data and on-site ground damage surveys. Despite the potential underestimation arising from the limitation of observations and the inherently stochastic nature of public reports, a total of 78 tornadoes and 40 waterspouts are identified. The results show that these tornadoes were primarily concentrated in Northeast China, the Beijing-Tianjin-Hebei Region, the Huang-Huai Region and the Pearl River Delta in 2024. Most tornadoes occurred between June and September, with July seeing tornadoes most frequently and their diurnal peaks in the afternoon. In addition, the intensities of 51 tornadoes are classified based on damage surveys into 12 EF0, 26 EF1, 9 EF2, and 4 EF3. In terms of waterspouts, they primarily occurred along the coastal region of South China and in the Bohai Bay, and most of them occurred in August with a pronounced diurnal peak around 06:00 BT. Overall, the tornadoes in 2024 were characterized by a high frequency of mass outbreaks, with four times of mass tornado events accounting for 44% of the annual total tornadoes. Notably, there were 13 tornadoes generated associated with an upper-level trough in Shandong Province on 5 July, making the province experiencing the highest occurrence frequency of tornadoes in 2024. Under the influence of the strong 2023 winter El Nio event, convective available potential energy in South China in spring 2024 was significantly higher than the climatological average. With such a favorable thermodynamic environment, 67% of tornadoes in Guangdong Province occurred from late March to late April, reflecting an unusually high early-spring concentration. Additionally, a high-impact nocturnal severe weather event in Nanchang, Jiangxi Province, underscored the persistent difficulties in identifying and confirming nighttime tornadoes.
Basic characteristics of tornadoes in China in 2024 are presented in this article based on comprehensive analysis of multi-source data and on-site ground damage surveys. Despite the potential underestimation arising from the limitation of observations and the inherently stochastic nature of public reports, a total of 78 tornadoes and 40 waterspouts are identified. The results show that these tornadoes were primarily concentrated in Northeast China, the Beijing-Tianjin-Hebei Region, the Huang-Huai Region and the Pearl River Delta in 2024. Most tornadoes occurred between June and September, with July seeing tornadoes most frequently and their diurnal peaks in the afternoon. In addition, the intensities of 51 tornadoes are classified based on damage surveys into 12 EF0, 26 EF1, 9 EF2, and 4 EF3. In terms of waterspouts, they primarily occurred along the coastal region of South China and in the Bohai Bay, and most of them occurred in August with a pronounced diurnal peak around 06:00 BT. Overall, the tornadoes in 2024 were characterized by a high frequency of mass outbreaks, with four times of mass tornado events accounting for 44% of the annual total tornadoes. Notably, there were 13 tornadoes generated associated with an upper-level trough in Shandong Province on 5 July, making the province experiencing the highest occurrence frequency of tornadoes in 2024. Under the influence of the strong 2023 winter El Nio event, convective available potential energy in South China in spring 2024 was significantly higher than the climatological average. With such a favorable thermodynamic environment, 67% of tornadoes in Guangdong Province occurred from late March to late April, reflecting an unusually high early-spring concentration. Additionally, a high-impact nocturnal severe weather event in Nanchang, Jiangxi Province, underscored the persistent difficulties in identifying and confirming nighttime tornadoes.
2026,52(6):742-749, DOI: 10.7519/j.issn.1000-0526.2026.022501
Abstract:
This paper proposes an online performance monitoring method for weather radars based on ground clutter characteristics to evaluate radar system status and enhance the stability and reliability of observation data. The method identifies stable ground clutter regions by exploiting the spatiotemporal persistence of clutter and the high occurrence probability of strong echoes. An empirical cumulative distribution function is then constructed, with the 98th percentile extracted as the monitoring indicator, and a relative calibration bias metric introduced to quantitatively characterize system deviations. A case study with the Jingzhou Radar demonstrates that this method can effectively capture stable clutter features under various weather conditions, different ranges, and anomalous propagation scenarios. Further application of the method to multiple radars in Hubei Province verify its reliability in detecting system performance biases and data anomalies, confirming its feasibility for online monitoring of weather radar performance. Therefore, this method is a strong support for improving the long-term stability of radar observations.
This paper proposes an online performance monitoring method for weather radars based on ground clutter characteristics to evaluate radar system status and enhance the stability and reliability of observation data. The method identifies stable ground clutter regions by exploiting the spatiotemporal persistence of clutter and the high occurrence probability of strong echoes. An empirical cumulative distribution function is then constructed, with the 98th percentile extracted as the monitoring indicator, and a relative calibration bias metric introduced to quantitatively characterize system deviations. A case study with the Jingzhou Radar demonstrates that this method can effectively capture stable clutter features under various weather conditions, different ranges, and anomalous propagation scenarios. Further application of the method to multiple radars in Hubei Province verify its reliability in detecting system performance biases and data anomalies, confirming its feasibility for online monitoring of weather radar performance. Therefore, this method is a strong support for improving the long-term stability of radar observations.
2026,52(6):750-758, DOI: 10.7519/j.issn.1000-0526.2025.081201
Abstract:
To investigate the impact of meteorological conditions on the key quality components (protein, fat, starch, and amino acids) of maize kernels, the stepwise regression-based prediction models are constructed based on the data from interval sowing experiments. The values calculated by the model are converted into quality grades and the goodness of fit and forecasting ability of the models are analyzed. The results show that all stepwise regression-based prediction models have passed the significance level test, and a relationship between maize kernel quality and meteorological factors from tasseling to milk stages and from milk to mature stages is established. Moreover, the linear relationship between maize kernel quality and meteorological factors is quantified. The results of the model test and forecast test indicate that the mean absolute percentage errors for four quality components are all below 15% and the predictions for starch and protein are closer to the observed values compared to those for fat and amino acids. The observed and predicted contents of maize kernel quality components (regardless of cropping system) are converted into grades for validation. For protein, fat and starch, the combined proportion of samples with predicted grades matching or within one grade of actual grades exceeds 90% (reaching 100% for starch), and is 76.67% for amino acids. The predicted grades aligns well with the actual grades, indicating that the prediction models exhibit high accuracy and can be used for forecasting and evaluating maize kernel quality. The findings can offer an objective and quantitative basis for optimizing environmental resource utilization to improve maize kernel quality and for informing maize ecological zoning.
To investigate the impact of meteorological conditions on the key quality components (protein, fat, starch, and amino acids) of maize kernels, the stepwise regression-based prediction models are constructed based on the data from interval sowing experiments. The values calculated by the model are converted into quality grades and the goodness of fit and forecasting ability of the models are analyzed. The results show that all stepwise regression-based prediction models have passed the significance level test, and a relationship between maize kernel quality and meteorological factors from tasseling to milk stages and from milk to mature stages is established. Moreover, the linear relationship between maize kernel quality and meteorological factors is quantified. The results of the model test and forecast test indicate that the mean absolute percentage errors for four quality components are all below 15% and the predictions for starch and protein are closer to the observed values compared to those for fat and amino acids. The observed and predicted contents of maize kernel quality components (regardless of cropping system) are converted into grades for validation. For protein, fat and starch, the combined proportion of samples with predicted grades matching or within one grade of actual grades exceeds 90% (reaching 100% for starch), and is 76.67% for amino acids. The predicted grades aligns well with the actual grades, indicating that the prediction models exhibit high accuracy and can be used for forecasting and evaluating maize kernel quality. The findings can offer an objective and quantitative basis for optimizing environmental resource utilization to improve maize kernel quality and for informing maize ecological zoning.
2026,52(6):759-768, DOI: 10.7519/j.issn.1000-0526.2026.060301
Abstract:
In March 2026, the Northern Hemisphere polar vortex exhibited a dipole pattern and was stronger than normal. The mid- to high-latitude circulation showed an anomalous four-wave pattern, and the circulation over Asia was relatively zonal. Positive geopotential height anomalies dominated nearly the entire Eurasian Continent. The western Pacific subtropical high was close to the climatological average, and the southern branch trough was intermittently active. The average temperature across China was 5.9℃, 1.2℃ higher than that in the same period of normal years. The national average precipitation was 35.3 mm, which was 19.6% above the normal level for the same period. Precipitation was abnormally more than normal in southern North China, Northwest China and central-western Xizang, but less in Northeast China, Jiang-Huai Region, eastnorthern and central-southern of Jiangnan Region and most parts of South China. During this month, there were two cold air processes, one sand-dust weather process and the first large-scale severe convective weather process of the year in China. Fog events occurred frequently over offshore and land-sea adjacent areas, and also over sea surface. Persistent rainy weather was significant in southern China.
In March 2026, the Northern Hemisphere polar vortex exhibited a dipole pattern and was stronger than normal. The mid- to high-latitude circulation showed an anomalous four-wave pattern, and the circulation over Asia was relatively zonal. Positive geopotential height anomalies dominated nearly the entire Eurasian Continent. The western Pacific subtropical high was close to the climatological average, and the southern branch trough was intermittently active. The average temperature across China was 5.9℃, 1.2℃ higher than that in the same period of normal years. The national average precipitation was 35.3 mm, which was 19.6% above the normal level for the same period. Precipitation was abnormally more than normal in southern North China, Northwest China and central-western Xizang, but less in Northeast China, Jiang-Huai Region, eastnorthern and central-southern of Jiangnan Region and most parts of South China. During this month, there were two cold air processes, one sand-dust weather process and the first large-scale severe convective weather process of the year in China. Fog events occurred frequently over offshore and land-sea adjacent areas, and also over sea surface. Persistent rainy weather was significant in southern China.
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Available online: June 24, 2026 , DOI: 10.7519/j.issn.1000-0526.2026.060101
Abstract:
This study utilizes 24-hour surface precipitation data from 08:00 to 08:00 (local time) and focuses on 83 heavy rainfall days in Beijing from 2016 to 2023. Based on the 500 hPa geopotential height field, the circulation patterns are classified into six categories: heavy rainfall associated with the Mongolian vortex and trough, heavy rainfall from the interaction between the subtropical high and westerly trough, heavy rainfall of the Hetao vortex type, heavy rainfall of the Northeast cold vortex type, heavy rainfall from tropical cyclones, and heavy rainfall resulting from the combination of westerly trough and typhoon. It was found that the Hetao vortex type and tropical cyclone type are more likely to produce widespread extreme heavy rainfall, while the Northeast cold vortex type mainly causes localized heavy rainfall and rarely results in widespread events.Statistical analysis of observational data from the Beijing station (54511) at 925, 850, 700, 500, and 200 hPa levels revealed that specific humidity at all levels during heavy rainfall periods is significantly higher than during non-heavy rainfall periods. Further analysis showed that, among the six types of heavy rainfall events, tropical cyclone and Hetao vortex events exhibit the highest specific humidity values, corresponding to the highest precipitation intensity and coverage.Using hourly precipitation data, precipitation occurring within one hour before and after the upper-air observation times (08:00 and 20:00) was categorized into three cases: heavy rainfall (≥10 mm), light rain (0.1–9.9 mm), and no precipitation. Statistical analysis of specific humidity at different levels showed that specific humidity is highest during heavy rainfall periods, followed by light rain periods, and lowest during no-rain periods.By combining jet stream analysis, the specific humidity characteristics of heavy rainfall processes corresponding to winds from eight directions at different levels were examined. It was found that specific humidity is highest when the wind direction is between 90° and 225° with a jet stream present, and lowest when the wind direction is between 270° and 300° with a jet stream. This study addresses the previous research focus on specific humidity characteristics below 700 hPa, particularly at 850 hPa, during heavy rainfall processes, while lacking analysis of higher levels. Innovatively, it reveals that an increase in specific humidity at the 500 hPa level has significant indicative value for heavy rainfall forecasting..
This study utilizes 24-hour surface precipitation data from 08:00 to 08:00 (local time) and focuses on 83 heavy rainfall days in Beijing from 2016 to 2023. Based on the 500 hPa geopotential height field, the circulation patterns are classified into six categories: heavy rainfall associated with the Mongolian vortex and trough, heavy rainfall from the interaction between the subtropical high and westerly trough, heavy rainfall of the Hetao vortex type, heavy rainfall of the Northeast cold vortex type, heavy rainfall from tropical cyclones, and heavy rainfall resulting from the combination of westerly trough and typhoon. It was found that the Hetao vortex type and tropical cyclone type are more likely to produce widespread extreme heavy rainfall, while the Northeast cold vortex type mainly causes localized heavy rainfall and rarely results in widespread events.Statistical analysis of observational data from the Beijing station (54511) at 925, 850, 700, 500, and 200 hPa levels revealed that specific humidity at all levels during heavy rainfall periods is significantly higher than during non-heavy rainfall periods. Further analysis showed that, among the six types of heavy rainfall events, tropical cyclone and Hetao vortex events exhibit the highest specific humidity values, corresponding to the highest precipitation intensity and coverage.Using hourly precipitation data, precipitation occurring within one hour before and after the upper-air observation times (08:00 and 20:00) was categorized into three cases: heavy rainfall (≥10 mm), light rain (0.1–9.9 mm), and no precipitation. Statistical analysis of specific humidity at different levels showed that specific humidity is highest during heavy rainfall periods, followed by light rain periods, and lowest during no-rain periods.By combining jet stream analysis, the specific humidity characteristics of heavy rainfall processes corresponding to winds from eight directions at different levels were examined. It was found that specific humidity is highest when the wind direction is between 90° and 225° with a jet stream present, and lowest when the wind direction is between 270° and 300° with a jet stream. This study addresses the previous research focus on specific humidity characteristics below 700 hPa, particularly at 850 hPa, during heavy rainfall processes, while lacking analysis of higher levels. Innovatively, it reveals that an increase in specific humidity at the 500 hPa level has significant indicative value for heavy rainfall forecasting..
Available online: June 18, 2026 , DOI: 10.7519/j.issn.1000-0526.2026.041602
Abstract:
Using conventional upper-air and surface observations, Doppler radar data, satellite nephogram and ERA5 reanalysis data, 451 drylines cases and 156 drylines cases triggering convection in Shandong Province from 2001 to 2022 were analyzed. Results are as follows: the total number of days for drylines in Shandong from 2001 to 2022 was 451 days, with 156 days triggering convective drylines. Drylines triggering convection occurred from April to September. May and the first ten-day period of May were the months and ten-day periods with the highest frequency of drylines occurrences. The primary occurrence time was between 14:00 and 17:00 (Beijing Time). The drylines are primarily distributed in central and northwestern Shandong. The formation of drylines is related to the influence of mountain ranges and the distribution of land and sea. The widths of convective and non-convective drylines are 75–106 km and 80–114 km, respectively, with dew point gradients of 11.8–16.7°C/(100 km) and 9.8–15°C/(100 km). Temperature distributions on both dry and wet sides of drylines range from 23 to 33°C, with a temperature gradient of 1–3 °C /(100 km), temperatures on the dry side are slightly higher. Compared to non-convective drylines, convective drylines exhibit higher temperatures and dew points on both the warm and cold sides, narrower widths, greater dew point gradients, this is related to the fact that the circulation associated with the force-driven component becomes stronger when the horizontal dew point gradient is large. The thresholds of the key environmental parameters for drylines triggering convection reveal that while vertical wind shear between 0-1 km and 0-3 km are difficult to distinguish due to minimal differences, other parameters including surface dew point temperature(Td), precipitable water (PW), CAPE, CIN, temperature difference between 850 and 500 hPa, DCAPE, severe weather threat index (SWEAT), and vertical wind shear between 0–6 km exhibit certain distinguishability between convective and non-convective drylines. The seasonal variation in convective parameters under unstable conditions is relatively small, but environmental parameters related to moisture conditions and vertical wind shear between 0–6 km exhibit significant seasonal differences. Therefore, their thresholds should be differentiated by season. Drylines frequently develop under conditions of northwest flow, ahead of westerly trough, and northeast low-pressure vortex at the upper-level 500 hPa. They are primarily influenced by the shear line of the low-pressure vortex or the northwest flow at the lower-level 700 hPa and 850 hPa, with the boundary layer often accompanied by shear lines. The surface situation is primarily situated within the convergence flow field of continental warm low or at the bottom or front of low-pressure systems.
Using conventional upper-air and surface observations, Doppler radar data, satellite nephogram and ERA5 reanalysis data, 451 drylines cases and 156 drylines cases triggering convection in Shandong Province from 2001 to 2022 were analyzed. Results are as follows: the total number of days for drylines in Shandong from 2001 to 2022 was 451 days, with 156 days triggering convective drylines. Drylines triggering convection occurred from April to September. May and the first ten-day period of May were the months and ten-day periods with the highest frequency of drylines occurrences. The primary occurrence time was between 14:00 and 17:00 (Beijing Time). The drylines are primarily distributed in central and northwestern Shandong. The formation of drylines is related to the influence of mountain ranges and the distribution of land and sea. The widths of convective and non-convective drylines are 75–106 km and 80–114 km, respectively, with dew point gradients of 11.8–16.7°C/(100 km) and 9.8–15°C/(100 km). Temperature distributions on both dry and wet sides of drylines range from 23 to 33°C, with a temperature gradient of 1–3 °C /(100 km), temperatures on the dry side are slightly higher. Compared to non-convective drylines, convective drylines exhibit higher temperatures and dew points on both the warm and cold sides, narrower widths, greater dew point gradients, this is related to the fact that the circulation associated with the force-driven component becomes stronger when the horizontal dew point gradient is large. The thresholds of the key environmental parameters for drylines triggering convection reveal that while vertical wind shear between 0-1 km and 0-3 km are difficult to distinguish due to minimal differences, other parameters including surface dew point temperature(Td), precipitable water (PW), CAPE, CIN, temperature difference between 850 and 500 hPa, DCAPE, severe weather threat index (SWEAT), and vertical wind shear between 0–6 km exhibit certain distinguishability between convective and non-convective drylines. The seasonal variation in convective parameters under unstable conditions is relatively small, but environmental parameters related to moisture conditions and vertical wind shear between 0–6 km exhibit significant seasonal differences. Therefore, their thresholds should be differentiated by season. Drylines frequently develop under conditions of northwest flow, ahead of westerly trough, and northeast low-pressure vortex at the upper-level 500 hPa. They are primarily influenced by the shear line of the low-pressure vortex or the northwest flow at the lower-level 700 hPa and 850 hPa, with the boundary layer often accompanied by shear lines. The surface situation is primarily situated within the convergence flow field of continental warm low or at the bottom or front of low-pressure systems.
Available online: June 16, 2026 , DOI: 10.7519/j.issn.1000-0526.2026.061101
Abstract:
The satellite-ground temperature difference was derived from the cloud top temperature of FY-4B and the air temperature of automatic weather stations. Combined with the cloud top height (CTH) observed by cloud radar, the Satellite-Ground Vertical Mean Temperature Lapse Rate (SG-VMTR) was calculated and compared with the temperature lapse rate (γ) fitted from the radiosonde temperature profile at the same stations. Meanwhile, the SG-VMTR was applied to other adjacent satellite pixels to achieve the fusion inversion of the satellite CTH in the surrounding area of the cloud radar installation point, and the inversion results were verified and analyzed. The results show that the SG-VMTR and γ values calculated at the same station were closely aligned and exhibited consistent temporal trends. The variation trends and statistical characteristics of the SG-VMTR at adjacent cloud radar stations were similar and can be used as substitutes to a certain extent. The correlation coefficient between the satellite-ground fusion inversion CTH and the cloud radar observed CTH was 0.9. Compared to FY-4B’s standalone CTH product, the RMSE decreased by approximately 720m, and the bias was reduced to -17.7m. This study lays a foundation for developing subsequent satellite-ground fusion regional CTH products.
The satellite-ground temperature difference was derived from the cloud top temperature of FY-4B and the air temperature of automatic weather stations. Combined with the cloud top height (CTH) observed by cloud radar, the Satellite-Ground Vertical Mean Temperature Lapse Rate (SG-VMTR) was calculated and compared with the temperature lapse rate (γ) fitted from the radiosonde temperature profile at the same stations. Meanwhile, the SG-VMTR was applied to other adjacent satellite pixels to achieve the fusion inversion of the satellite CTH in the surrounding area of the cloud radar installation point, and the inversion results were verified and analyzed. The results show that the SG-VMTR and γ values calculated at the same station were closely aligned and exhibited consistent temporal trends. The variation trends and statistical characteristics of the SG-VMTR at adjacent cloud radar stations were similar and can be used as substitutes to a certain extent. The correlation coefficient between the satellite-ground fusion inversion CTH and the cloud radar observed CTH was 0.9. Compared to FY-4B’s standalone CTH product, the RMSE decreased by approximately 720m, and the bias was reduced to -17.7m. This study lays a foundation for developing subsequent satellite-ground fusion regional CTH products.
Available online: June 12, 2026 , DOI: 10.7519/j.issn.1000-0526.2026.012301
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In this study, we conduct a statistical verification and analysis on near-surface temperature, wind speed and precipitation forecasts during the warm season in Zhejiang using CMA regional ensemble prediction systems at 3-km and 10-km horizontal resolutions (CMA-REPS 3 km and CMA-REPS 10 km). The study results, which provide a scientific basis for objectively evaluating CMA multi-horizontal-resolution regional ensemble prediction systems across various terrains and for subsequent improvements in ensemble forecasting methods, can be summarized as follows. (1) Both CMA-REPS effectively capture the diurnal variations of near-surface elements. However, the forecasts exhibit a negative bias in temperature and overestimation of wind speed, while overestimating precipitation from afternoon to early morning. (2) Compared to CMA-REPS 10 km, CMA-REPS 3 km reduces forecast errors for temperature and wind speed, with a maximum decrease of 23.07% in continuous ranked probability score(CRPS). It also enhances the detectability of precipitation forecast, improving the area of relative operating characteristic(AROC) by up to 19%. Meanwhile, CMA-REPS 3 km demonstrates superior fraction skill score(FSS) for heavy rainfall and provides more accurate forecast in diurnal variations of near-surface elements. However, the spread of early forecast is smaller. (3) In complex terrains, CMA-REPS 3 km shows significant improvements in the probability forecast errors of temperature and wind speed. Additionally, CMA-REPS 3 km exhibits the better spread-skill relationship for wind speed in hilly and mountainous, as well as for temperature in plain and basin. Not only that, CMA-REPS 3 km has better capability for the spread of heavy precipitation and the development of rain bands in steep terrain areas. As such, CMA-REPS 3 km demonstrates superior near-surface forecasting capability over complex terrains, particularly for 2 m temperature, 10 m wind speed and precipitation.
In this study, we conduct a statistical verification and analysis on near-surface temperature, wind speed and precipitation forecasts during the warm season in Zhejiang using CMA regional ensemble prediction systems at 3-km and 10-km horizontal resolutions (CMA-REPS 3 km and CMA-REPS 10 km). The study results, which provide a scientific basis for objectively evaluating CMA multi-horizontal-resolution regional ensemble prediction systems across various terrains and for subsequent improvements in ensemble forecasting methods, can be summarized as follows. (1) Both CMA-REPS effectively capture the diurnal variations of near-surface elements. However, the forecasts exhibit a negative bias in temperature and overestimation of wind speed, while overestimating precipitation from afternoon to early morning. (2) Compared to CMA-REPS 10 km, CMA-REPS 3 km reduces forecast errors for temperature and wind speed, with a maximum decrease of 23.07% in continuous ranked probability score(CRPS). It also enhances the detectability of precipitation forecast, improving the area of relative operating characteristic(AROC) by up to 19%. Meanwhile, CMA-REPS 3 km demonstrates superior fraction skill score(FSS) for heavy rainfall and provides more accurate forecast in diurnal variations of near-surface elements. However, the spread of early forecast is smaller. (3) In complex terrains, CMA-REPS 3 km shows significant improvements in the probability forecast errors of temperature and wind speed. Additionally, CMA-REPS 3 km exhibits the better spread-skill relationship for wind speed in hilly and mountainous, as well as for temperature in plain and basin. Not only that, CMA-REPS 3 km has better capability for the spread of heavy precipitation and the development of rain bands in steep terrain areas. As such, CMA-REPS 3 km demonstrates superior near-surface forecasting capability over complex terrains, particularly for 2 m temperature, 10 m wind speed and precipitation.
Available online: June 09, 2026 , DOI: 10.7519/j.issn.1000-0526.2026.050901
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Based on the cloud products from FY-4A satellite and the raindrop spectrometer data in Zhejiang Province, this paper analyses the characteristics of summer precipitation and its relationship with cloud parameters from 2020 to 2022. Results showed that in the summer of Zhejiang, the occurrence ratio of moderate rainfall was the highest in different precipitation levels, storm rainfall mostly occurred in the mountainous areas of southern Zhejiang, and the occurrence ratio of convective cloud precipitation in this area was also the highest. The relationship between precipitation characteristics and cloud parameters was manifested as follows: The probability of light rainfall is highest for water cloud and cirrus cloud, supercooled water cloud and mixed cloud precipitation is mainly concentrated in moderate to heavy rainfall, ice cloud have the highest probability of heavy rainfall, particularly storm rainfall, the precipitation characteristics of multi-layer cloud might be similar to those of water cloud. The average precipitation intensity increased with the decrease of cloud top temperature (CTT) and the increase of cloud optical thickness (COT), but the correlation with cloud effective particle radius (CER) was not strong in this study. Combining two parameters (CTT and COT) demonstrates the gradient variation of precipitation intensity and its higher sensitivity to COT, with heavy precipitation more likely to occur under low CTT and high COT. Incorporating CER to construct a three-parameter combination further reflects the effect of cloud droplet coalescence efficiency on precipitation microphysical processes, leading to more precise precipitation estimation. Convective cloud precipitation had the characteristics of lower CTT and larger COT compared with stratiform cloud precipitation, but the stratiform cloud precipitation was often accompanied by convective processes. In the future, statistical relationships between similar cloud products from different satellites and precipitation in other regions can be established to provide a reference for guiding weather modification operations precisely.
Based on the cloud products from FY-4A satellite and the raindrop spectrometer data in Zhejiang Province, this paper analyses the characteristics of summer precipitation and its relationship with cloud parameters from 2020 to 2022. Results showed that in the summer of Zhejiang, the occurrence ratio of moderate rainfall was the highest in different precipitation levels, storm rainfall mostly occurred in the mountainous areas of southern Zhejiang, and the occurrence ratio of convective cloud precipitation in this area was also the highest. The relationship between precipitation characteristics and cloud parameters was manifested as follows: The probability of light rainfall is highest for water cloud and cirrus cloud, supercooled water cloud and mixed cloud precipitation is mainly concentrated in moderate to heavy rainfall, ice cloud have the highest probability of heavy rainfall, particularly storm rainfall, the precipitation characteristics of multi-layer cloud might be similar to those of water cloud. The average precipitation intensity increased with the decrease of cloud top temperature (CTT) and the increase of cloud optical thickness (COT), but the correlation with cloud effective particle radius (CER) was not strong in this study. Combining two parameters (CTT and COT) demonstrates the gradient variation of precipitation intensity and its higher sensitivity to COT, with heavy precipitation more likely to occur under low CTT and high COT. Incorporating CER to construct a three-parameter combination further reflects the effect of cloud droplet coalescence efficiency on precipitation microphysical processes, leading to more precise precipitation estimation. Convective cloud precipitation had the characteristics of lower CTT and larger COT compared with stratiform cloud precipitation, but the stratiform cloud precipitation was often accompanied by convective processes. In the future, statistical relationships between similar cloud products from different satellites and precipitation in other regions can be established to provide a reference for guiding weather modification operations precisely.
Available online: June 09, 2026 , DOI: 10.7519/j.issn.1000-0526.2025.112401
Abstract:
To conduct a quantitative study on the sidelobe echoes of the S-band dual-polarization weather radar, based on the Plan Position Indicator (PPI) data of five SAD-type Doppler dual-polarization weather radars in Changsha, Chenzhou, Changde, Xiangxi and Huaihua in Hunan Province from 2021 to 2025, 445 sidelobe echo samples were manually screened in this study. On this basis, a numerical matrix was constructed and the values of sidelobe echoes from four types of products were extracted, including horizontal polarization reflectivity factor (ZH), differential reflectivity factor (ZDR), correlation coefficient (CC), and differential phase shift rate (KDP). Statistical analysis was conducted on the spatial distribution characteristics of sidelobe echoes and the average value characteristics of various products. The results show that the sidelobe echoes are evenly distributed in the east-west direction, with fewer echoes in the south and more in the north, in the radar polar coordinate system. The areas with the highest occurrence frequency of sidelobe echoes are concentrated in the range from the radar static cone area to 100 km and at the melting layer height of 3.0-4.0 km. The sidelobe echoes mainly appear within the range of ±6 km in radial distance from the high echo core and 4°-40° in azimuth, and the highest frequency is located at the same radial distance as the high echo core and 12°-13° azimuth on the lateral side. The sidelobe echoes have significant low-value characteristics in radar polarization parameters. 75% of the sidelobe echoes exhibit ZH ≤ 8.0 dBz, ZDR ≤ 0.56 dB, and CC ≤ 0.92, with ZH most frequently occurring in 0-5 dBz, ZDR in 0-1 dB, and CC in 0.9-1.0. Although the low values of polarimetric radar variables in sidelobe echoes are distinct, 26.0% of the samples with azimuthal spans ≥30° exhibit a terminal ZDR ≥ 5 dB. The research results are conducive to improving the identification efficiency of sidelobe echoes and a valuable basis for future’s automatic identification of sidelobe echoes.
To conduct a quantitative study on the sidelobe echoes of the S-band dual-polarization weather radar, based on the Plan Position Indicator (PPI) data of five SAD-type Doppler dual-polarization weather radars in Changsha, Chenzhou, Changde, Xiangxi and Huaihua in Hunan Province from 2021 to 2025, 445 sidelobe echo samples were manually screened in this study. On this basis, a numerical matrix was constructed and the values of sidelobe echoes from four types of products were extracted, including horizontal polarization reflectivity factor (ZH), differential reflectivity factor (ZDR), correlation coefficient (CC), and differential phase shift rate (KDP). Statistical analysis was conducted on the spatial distribution characteristics of sidelobe echoes and the average value characteristics of various products. The results show that the sidelobe echoes are evenly distributed in the east-west direction, with fewer echoes in the south and more in the north, in the radar polar coordinate system. The areas with the highest occurrence frequency of sidelobe echoes are concentrated in the range from the radar static cone area to 100 km and at the melting layer height of 3.0-4.0 km. The sidelobe echoes mainly appear within the range of ±6 km in radial distance from the high echo core and 4°-40° in azimuth, and the highest frequency is located at the same radial distance as the high echo core and 12°-13° azimuth on the lateral side. The sidelobe echoes have significant low-value characteristics in radar polarization parameters. 75% of the sidelobe echoes exhibit ZH ≤ 8.0 dBz, ZDR ≤ 0.56 dB, and CC ≤ 0.92, with ZH most frequently occurring in 0-5 dBz, ZDR in 0-1 dB, and CC in 0.9-1.0. Although the low values of polarimetric radar variables in sidelobe echoes are distinct, 26.0% of the samples with azimuthal spans ≥30° exhibit a terminal ZDR ≥ 5 dB. The research results are conducive to improving the identification efficiency of sidelobe echoes and a valuable basis for future’s automatic identification of sidelobe echoes.
Available online: June 05, 2026 , DOI: 10.7519/j.issn.1000-0526.2026.050201
Abstract:
Summary: Based on China''s design codes for building structures and major overhead transmission lines, this study adopts the generalized extreme value distribution theory and historical surface meteorological monitoring data to calculate the return period basic wind speeds and basic wind pressures at 5-year, 10-year, 15-year, 30-year, 50-year and 100-year intervals for meteorological observation stations. This paper takes the wind pressure generated by the maximum typhoon wind and the extreme wind pressure generated by extreme gale as the disaster-inducing factors of typhoon gale for transmission lines, and establishes a disaster assessment model for transmission lines under typhoon gale by combining the wind pressure disaster threshold indicators of different types of transmission lines: low-voltage (≤1 kV), medium-voltage (10 kV–35 kV), high-voltage (66 kV–220 kV), and ultra-high voltage and above (≥330 kV). According to the impact of typhoon gale on transmission lines, the disaster level of typhoon gale on transmission lines is divided into four grades: medium, relatively high, high and extremely high, and the corresponding disaster impacts on low-voltage transmission lines, medium-voltage transmission lines, high-voltage transmission lines, ultra-high voltage and above transmission lines are specified. The disaster data from the meteorological disaster management system of the China Meteorological Administration between 2012 and 2023 are used to verify the rationality of the developed disaster assessment model for transmission lines under typhoon gale. Among the 205 samples with transmission line damage or power supply interruption caused by typhoons, the model identifies 183 samples with disaster risk on transmission lines, achieving an assessment accuracy of 89.3%. For the 162 samples of power disasters caused by typhoons of typhoon-level or above intensity landing in China, the model identifies 146 samples with disaster risk on transmission lines. Among these, the proportions of samples with medium, relatively high, high and extremely high grades in the total samples are 26.5%, 36.4%, 14.8% and 12.3% respectively, and the assessment accuracy reaches 90.1%, indicating that the overall performance of the model is satisfactory. The developed assessment model can conduct pre-disaster pre-assessment and rapid post-disaster assessment by combining typhoon forecast or real observation data, which provides scientific and technological support for typhoon meteorological services for the power industry.
Summary: Based on China''s design codes for building structures and major overhead transmission lines, this study adopts the generalized extreme value distribution theory and historical surface meteorological monitoring data to calculate the return period basic wind speeds and basic wind pressures at 5-year, 10-year, 15-year, 30-year, 50-year and 100-year intervals for meteorological observation stations. This paper takes the wind pressure generated by the maximum typhoon wind and the extreme wind pressure generated by extreme gale as the disaster-inducing factors of typhoon gale for transmission lines, and establishes a disaster assessment model for transmission lines under typhoon gale by combining the wind pressure disaster threshold indicators of different types of transmission lines: low-voltage (≤1 kV), medium-voltage (10 kV–35 kV), high-voltage (66 kV–220 kV), and ultra-high voltage and above (≥330 kV). According to the impact of typhoon gale on transmission lines, the disaster level of typhoon gale on transmission lines is divided into four grades: medium, relatively high, high and extremely high, and the corresponding disaster impacts on low-voltage transmission lines, medium-voltage transmission lines, high-voltage transmission lines, ultra-high voltage and above transmission lines are specified. The disaster data from the meteorological disaster management system of the China Meteorological Administration between 2012 and 2023 are used to verify the rationality of the developed disaster assessment model for transmission lines under typhoon gale. Among the 205 samples with transmission line damage or power supply interruption caused by typhoons, the model identifies 183 samples with disaster risk on transmission lines, achieving an assessment accuracy of 89.3%. For the 162 samples of power disasters caused by typhoons of typhoon-level or above intensity landing in China, the model identifies 146 samples with disaster risk on transmission lines. Among these, the proportions of samples with medium, relatively high, high and extremely high grades in the total samples are 26.5%, 36.4%, 14.8% and 12.3% respectively, and the assessment accuracy reaches 90.1%, indicating that the overall performance of the model is satisfactory. The developed assessment model can conduct pre-disaster pre-assessment and rapid post-disaster assessment by combining typhoon forecast or real observation data, which provides scientific and technological support for typhoon meteorological services for the power industry.
Available online: June 05, 2026 , DOI: 10.7519/j.issn.1000-0526.2025.121001
Abstract:
Hail weather is characterized by sudden onset, pronounced locality, and significant destructive power, posing multiple adverse impacts on human production and daily life. Accurate and timely identification of hail weather holds critical importance for disaster early warning and prevention. Although Doppler weather radar observations play a vital role in hail identification, the limited spatiotemporal coverage of single-source radar data and the insufficient timeliness and accuracy of traditional identification methods remain challenging. To address the limitations of single data sources, this study proposes a hail identification method based on satellite and radar data fusion. Leveraging the spatiotemporal complementarity between satellite and radar data, the method combines threshold characteristics of satellite and radar observations before and after hailfall to achieve efficient multi-source data fusion and identification through deep learning algorithms. Experimental results demonstrate that the proposed method effectively integrates satellite and radar data, with the YOLOv7 model achieving a recognition accuracy of 90.83%. It successfully identifies hail-affected regions, providing crucial references for hail weather early warning. Notably, in areas where radar data are susceptible to terrain occlusion, the method significantly mitigates inaccurate hail region identification caused by poor data quality, demonstrating high practical value.
Hail weather is characterized by sudden onset, pronounced locality, and significant destructive power, posing multiple adverse impacts on human production and daily life. Accurate and timely identification of hail weather holds critical importance for disaster early warning and prevention. Although Doppler weather radar observations play a vital role in hail identification, the limited spatiotemporal coverage of single-source radar data and the insufficient timeliness and accuracy of traditional identification methods remain challenging. To address the limitations of single data sources, this study proposes a hail identification method based on satellite and radar data fusion. Leveraging the spatiotemporal complementarity between satellite and radar data, the method combines threshold characteristics of satellite and radar observations before and after hailfall to achieve efficient multi-source data fusion and identification through deep learning algorithms. Experimental results demonstrate that the proposed method effectively integrates satellite and radar data, with the YOLOv7 model achieving a recognition accuracy of 90.83%. It successfully identifies hail-affected regions, providing crucial references for hail weather early warning. Notably, in areas where radar data are susceptible to terrain occlusion, the method significantly mitigates inaccurate hail region identification caused by poor data quality, demonstrating high practical value.
Available online: June 04, 2026 , DOI: 10.7519/j.issn.1000-0526.2026.060401
Abstract:
In November 2024, the precipitation in Heilongjiang Province reached 31.5 mm, ranking as the 4th highest in the same period since 1961. An extreme precipitation event during 25–29 November contributed 73% of the total monthly precipitation, with its 5-day accumulated precipitation being 13.5 times the climatological average for the same period. Analysis of the circulation evolution revealed a clear two-phase variation in the mid- to high-latitude circulation over Eurasia. In the early phase (1–24 November), precipitation was suppressed by a "negative in the west, positive in the east" geopotential height anomaly pattern, corresponding to below-normal precipitation. During the late phase ((25–29 November), the circulation adjusted to an "inverted Ω" pattern, characterized by the establishment of dual blocking highs over the Ural Mountains and the Sea of Okhotsk, which formed a stable configuration with the northeast cold vortex (NECV). This configuration guided the southward intrusion of polar cold air, which intensely converged with the warm and moist air transported by a low-level jet over Heilongjiang, enhancing moisture convergence and dynamic lifting. Influenced by the locked phase of the dual blocking highs, this weather system remained stagnant over the region, ultimately triggering a persistent, widespread heavy precipitation event. Statistics show that 4 of the 10 wettest Novembers in Heilongjiang since 1961 were dominated by single extreme precipitation events, revealing the critical role of synoptic-scale system adjustments in causing November precipitation anomalies. These results enhance our understanding of the causes of extreme precipitation in November in Heilongjiang Province and provide important references for its prediction.
In November 2024, the precipitation in Heilongjiang Province reached 31.5 mm, ranking as the 4th highest in the same period since 1961. An extreme precipitation event during 25–29 November contributed 73% of the total monthly precipitation, with its 5-day accumulated precipitation being 13.5 times the climatological average for the same period. Analysis of the circulation evolution revealed a clear two-phase variation in the mid- to high-latitude circulation over Eurasia. In the early phase (1–24 November), precipitation was suppressed by a "negative in the west, positive in the east" geopotential height anomaly pattern, corresponding to below-normal precipitation. During the late phase ((25–29 November), the circulation adjusted to an "inverted Ω" pattern, characterized by the establishment of dual blocking highs over the Ural Mountains and the Sea of Okhotsk, which formed a stable configuration with the northeast cold vortex (NECV). This configuration guided the southward intrusion of polar cold air, which intensely converged with the warm and moist air transported by a low-level jet over Heilongjiang, enhancing moisture convergence and dynamic lifting. Influenced by the locked phase of the dual blocking highs, this weather system remained stagnant over the region, ultimately triggering a persistent, widespread heavy precipitation event. Statistics show that 4 of the 10 wettest Novembers in Heilongjiang since 1961 were dominated by single extreme precipitation events, revealing the critical role of synoptic-scale system adjustments in causing November precipitation anomalies. These results enhance our understanding of the causes of extreme precipitation in November in Heilongjiang Province and provide important references for its prediction.
Available online: June 03, 2026 , DOI: 10.7519/j.issn.1000-0526.2026.010801
Abstract:
本文基于注意力机制和编码-解码结构设计了OF-RainNet降水预报模型，实现了降水平流外推运动信息和深度学习模型的有效融合。以北京地区为试验区域，构建1km分辨率，逐6分钟的1h和2h的降水临近预报试验，得到如下结论： 1） 模型以SWAN的1hQPE和0-2hQPF作为输入数据，通过编码阶段显式输入SWAN外推产品，实现传统外推和深度学习模型的融合。模型引入SuperTokenAttention超级词元注意力模块结构，提取面向降水临近预报有意义的语义单元并计算多头注意力，设计分段权重的损失函数，最终实现降水的1h和2h临近预报。 2） 通过2024年7-8月和2025年7-8月北京试验区长时间序列对比试验发现，OF-RainNet在5mm/h，10mm/h，20mm/h，50mm/h的1h、2h预报时效的TS评分全部高于SWAN-QPF和PredRNNV2模型，其中在≥10mm/h的阈值段内，相对提升超过10%，说明OF-RainNet融合外推预报和深度学习模型后能获得正预报技巧，强降水预报性能提升明显。 3） 相较于未引入光流外推产品和STA模块的基础版本模型，OF-RainNet的TS评分显著提升，强降水Bias略高于1。说明模型通过引入STA模块和外推产品，能够有效提升模型的强降水预报能力。 4） 通过个例分析发现，OF-RainNet的预报性能优于PredRNNv2，对强降水持续阶段的预报能力优于局地触发阶段，1h预报优于2h预报OF-RainNet的1h预报明显优于2h预报，强降水持续阶段的预报能力优于强降水局地触发阶段。 预报试验结果表明，仅依赖雷达观测的外推预报，难以捕捉强降水的局地精细化发展演变特征，尤其是对局地触发的强降水预报技巧较低。本文通过深度学习模型构建多源预报数据融合框架，实现了不同预报方法数据的有效融合，为未来的工作提供了新的思路和技术方向。后续研究可在模型输入层扩展不同方法的预报产品，如“风雷”预报产品、数值模式环境场，物理量场和回波预报场等。通过深度学习模型挖掘各类预报产品的核心优势，实现多预报方法的集成融合，进一步提升临近客观预报对降水生消演变的预报能力。
本文基于注意力机制和编码-解码结构设计了OF-RainNet降水预报模型，实现了降水平流外推运动信息和深度学习模型的有效融合。以北京地区为试验区域，构建1km分辨率，逐6分钟的1h和2h的降水临近预报试验，得到如下结论： 1） 模型以SWAN的1hQPE和0-2hQPF作为输入数据，通过编码阶段显式输入SWAN外推产品，实现传统外推和深度学习模型的融合。模型引入SuperTokenAttention超级词元注意力模块结构，提取面向降水临近预报有意义的语义单元并计算多头注意力，设计分段权重的损失函数，最终实现降水的1h和2h临近预报。 2） 通过2024年7-8月和2025年7-8月北京试验区长时间序列对比试验发现，OF-RainNet在5mm/h，10mm/h，20mm/h，50mm/h的1h、2h预报时效的TS评分全部高于SWAN-QPF和PredRNNV2模型，其中在≥10mm/h的阈值段内，相对提升超过10%，说明OF-RainNet融合外推预报和深度学习模型后能获得正预报技巧，强降水预报性能提升明显。 3） 相较于未引入光流外推产品和STA模块的基础版本模型，OF-RainNet的TS评分显著提升，强降水Bias略高于1。说明模型通过引入STA模块和外推产品，能够有效提升模型的强降水预报能力。 4） 通过个例分析发现，OF-RainNet的预报性能优于PredRNNv2，对强降水持续阶段的预报能力优于局地触发阶段，1h预报优于2h预报OF-RainNet的1h预报明显优于2h预报，强降水持续阶段的预报能力优于强降水局地触发阶段。 预报试验结果表明，仅依赖雷达观测的外推预报，难以捕捉强降水的局地精细化发展演变特征，尤其是对局地触发的强降水预报技巧较低。本文通过深度学习模型构建多源预报数据融合框架，实现了不同预报方法数据的有效融合，为未来的工作提供了新的思路和技术方向。后续研究可在模型输入层扩展不同方法的预报产品，如“风雷”预报产品、数值模式环境场，物理量场和回波预报场等。通过深度学习模型挖掘各类预报产品的核心优势，实现多预报方法的集成融合，进一步提升临近客观预报对降水生消演变的预报能力。
Available online: May 29, 2026 , DOI: 10.7519/j.issn.1000-0526.2026.052501
Abstract:
During the prolonged operation of weather radar systems, equipment malfunctions and external interferences frequently result in abnormal radar echoes. These anomalies impair the radar’s effectiveness in monitoring, warning, and forecasting severe weather events. To address this issue, this study manually labeled radial and circular types of abnormal echoes based on historical data, and utilized data augmentation techniques to construct a radar mosaic dataset of abnormal echoes consisting of 20,000 images. Building upon the advanced semantic segmentation model DeepLabv3+, we introduced several optimizations: first, a streamlined ResNet50 backbone with reduced parameters was adopted; second, the SimAM attention mechanism to enhance feature extraction and emphasize critical features was incorporated; third, intermediate layers in the decoder path are added to integrate additional details and contextual information through layer fusion. Consequently, the DeepLab-ARER model for recognition of abnormal radar echo in radar mosaic data was developed. Experimental evaluations demonstrated that DeepLab-ARER achieved superior performance in identifying both types of abnormal echoes, with a mean pixel accuracy (MPA) of 96.75% and a mean intersection-over-union (MIOU) of 93.95%, representing significant improvements over the original DeepLabv3+ model. This research provides robust technical solutions for the automatic recognition of abnormal echoes in radar mosaic data and establishes a solid foundation for enhancing the quality of radar mosaic data in operational applications.
During the prolonged operation of weather radar systems, equipment malfunctions and external interferences frequently result in abnormal radar echoes. These anomalies impair the radar’s effectiveness in monitoring, warning, and forecasting severe weather events. To address this issue, this study manually labeled radial and circular types of abnormal echoes based on historical data, and utilized data augmentation techniques to construct a radar mosaic dataset of abnormal echoes consisting of 20,000 images. Building upon the advanced semantic segmentation model DeepLabv3+, we introduced several optimizations: first, a streamlined ResNet50 backbone with reduced parameters was adopted; second, the SimAM attention mechanism to enhance feature extraction and emphasize critical features was incorporated; third, intermediate layers in the decoder path are added to integrate additional details and contextual information through layer fusion. Consequently, the DeepLab-ARER model for recognition of abnormal radar echo in radar mosaic data was developed. Experimental evaluations demonstrated that DeepLab-ARER achieved superior performance in identifying both types of abnormal echoes, with a mean pixel accuracy (MPA) of 96.75% and a mean intersection-over-union (MIOU) of 93.95%, representing significant improvements over the original DeepLabv3+ model. This research provides robust technical solutions for the automatic recognition of abnormal echoes in radar mosaic data and establishes a solid foundation for enhancing the quality of radar mosaic data in operational applications.
Available online: May 21, 2026 , DOI: 10.7519/j.issn.1000-0526.2026.051302
Abstract:
Addressing the persistent demand for historical analogue references in operational weather forecasting and the deficiencies of traditional retrieval methods in efficiency and objectivity, this paper proposes a rapid retrieval technology for similar historical weather events based on image fingerprinting and multi-element synergy. Technology initially employs fingerprint similarity detection algorithms from imageology to establish a similarity quantification method for single weather element fields. Subsequently, guided by synoptic principles and considering the coupling characteristics between upper-air circulation and surface element fields, a multi-element synergistic query algorithm is designed to more accurately identify historical precipitation fields and corresponding circulation patterns like a target weather process. Based on these techniques, a historical similar weather retrieval platform was developed using a "Cloud + Client" architecture, enabling efficient retrieval of historical analogues. The platform has been operationally trialed at the National Meteorological Center, demonstrating good application potential and practical value in forecasting several weather events. Statistical verification indicates that the similar cases retrieved by this method significantly outperform climatological states in terms of anomaly correlation coefficient and root mean square error. Finally, this paper discusses future development directions for technology, particularly in algorithm optimization, objective evaluation, and deepening application.
Addressing the persistent demand for historical analogue references in operational weather forecasting and the deficiencies of traditional retrieval methods in efficiency and objectivity, this paper proposes a rapid retrieval technology for similar historical weather events based on image fingerprinting and multi-element synergy. Technology initially employs fingerprint similarity detection algorithms from imageology to establish a similarity quantification method for single weather element fields. Subsequently, guided by synoptic principles and considering the coupling characteristics between upper-air circulation and surface element fields, a multi-element synergistic query algorithm is designed to more accurately identify historical precipitation fields and corresponding circulation patterns like a target weather process. Based on these techniques, a historical similar weather retrieval platform was developed using a "Cloud + Client" architecture, enabling efficient retrieval of historical analogues. The platform has been operationally trialed at the National Meteorological Center, demonstrating good application potential and practical value in forecasting several weather events. Statistical verification indicates that the similar cases retrieved by this method significantly outperform climatological states in terms of anomaly correlation coefficient and root mean square error. Finally, this paper discusses future development directions for technology, particularly in algorithm optimization, objective evaluation, and deepening application.
Available online: May 20, 2026 , DOI: 10.7519/j.issn.1000-0526.2026.051401
Abstract:
Using conventional observations, dense surface automatic station data, NCEP/FNL reanalysis, Doppler radar data, and WRF model simulations, this study investigates a severe convective event triggered by the collision between a gust front and a sea breeze front in Xiamen, China, and examines its underlying mechanisms. The results show that the event occurred at the edge of the subtropical high, where upper-level divergence overlapped with low-level convergence. An unstable thermodynamic stratification characterized by dry upper levels and moist lower levels, together with strong thermal instability, provided a favorable environment for convective development. The cold outflow generated by earlier convective cells expanded outward to form a gust front, while the sea breeze front developed continuously along the Xiamen coast. After the two boundaries collided near the urban area of Xiamen, low-level convergence and local lifting were markedly enhanced, thereby initiating convection. WRF simulations further indicate that following the collision, the shallow-layer specific humidity in the collision region increased by about 2.5 g·kg?1, the maximum convective available potential energy increased by more than 1000 J·kg?1, and the vorticity intensified to 25×10?? s?1, suggesting significant enhancement of moisture supply, instability, and dynamic lifting. The convergence-induced ascent allowed air parcels to overcome the level of free convection, thereby initiating and sustaining convection. Subsequently, convective cells near the collision zone merged and triggered a cloud-bridge cell, which further developed into a multicellular merging process and produced short-duration heavy rainfall in Xiamen. Thereafter, a surface convergence line and shallow shear system on the rear side of the collision region maintained a deeper convergence-ascent structure. In combination with sufficient moisture and instability, the model indicated a subsequent convective regeneration process. The findings suggest that the collision between a gust front and a sea breeze front can trigger and sustain severe convection through enhanced low-level convergence, moisture transport, and instability, providing useful implications for nowcasting and warning of local severe convection in Xiamen and other coastal areas.
Using conventional observations, dense surface automatic station data, NCEP/FNL reanalysis, Doppler radar data, and WRF model simulations, this study investigates a severe convective event triggered by the collision between a gust front and a sea breeze front in Xiamen, China, and examines its underlying mechanisms. The results show that the event occurred at the edge of the subtropical high, where upper-level divergence overlapped with low-level convergence. An unstable thermodynamic stratification characterized by dry upper levels and moist lower levels, together with strong thermal instability, provided a favorable environment for convective development. The cold outflow generated by earlier convective cells expanded outward to form a gust front, while the sea breeze front developed continuously along the Xiamen coast. After the two boundaries collided near the urban area of Xiamen, low-level convergence and local lifting were markedly enhanced, thereby initiating convection. WRF simulations further indicate that following the collision, the shallow-layer specific humidity in the collision region increased by about 2.5 g·kg?1, the maximum convective available potential energy increased by more than 1000 J·kg?1, and the vorticity intensified to 25×10?? s?1, suggesting significant enhancement of moisture supply, instability, and dynamic lifting. The convergence-induced ascent allowed air parcels to overcome the level of free convection, thereby initiating and sustaining convection. Subsequently, convective cells near the collision zone merged and triggered a cloud-bridge cell, which further developed into a multicellular merging process and produced short-duration heavy rainfall in Xiamen. Thereafter, a surface convergence line and shallow shear system on the rear side of the collision region maintained a deeper convergence-ascent structure. In combination with sufficient moisture and instability, the model indicated a subsequent convective regeneration process. The findings suggest that the collision between a gust front and a sea breeze front can trigger and sustain severe convection through enhanced low-level convergence, moisture transport, and instability, providing useful implications for nowcasting and warning of local severe convection in Xiamen and other coastal areas.
Available online: May 19, 2026 , DOI: 10.7519/j.issn.1000-0526.2026.050702
Abstract:
To address the characteristics of X-band phased array radar, which offers high spatiotemporal resolution but limited observation coverage and various data reliability errors, this study proposes a high-quality data fusion method with S-band operational radar. First, the optical flow method is applied to extrapolate the motion trends of S-band radar data, enhancing its temporal resolution from the original 6 minutes to 1.5 minutes, synchronized with X-band radar. Subsequently, the optimal interpolation algorithm and pyramid transform algorithm are employed for spatial fusion of dual-band radar data, yielding the corresponding products SXnet-O and SXnet-K. Statistical analysis based on nearly 5,000 radar volume scanscases from the Guangdong-Hong Kong-Macao Greater Bay Area radar network during May–June 2022 demonstrates that the fused data achieve a 12% improvement in temporal correlation coefficient and a 28% reduction in root mean square error compared to the original X-band data. The spatial coverage reaches 96% of the union area of both radars, approximately 30% higher than that of a single radar. Comparative results indicate that SXnet-O significantly outperforms SXnet-K in system bias control (92% of deviations within ±2 dB), parameter consistency, and boundary stability. For data correction, SXnet-O reduces the deviation from the S-band reference by 5% compared to the original X-band data while effectively integrating the structural precision of X-band with the observational stability of S-band. This method provides a methodological foundation for data fusion applications in dense phased array weather radar networks.
To address the characteristics of X-band phased array radar, which offers high spatiotemporal resolution but limited observation coverage and various data reliability errors, this study proposes a high-quality data fusion method with S-band operational radar. First, the optical flow method is applied to extrapolate the motion trends of S-band radar data, enhancing its temporal resolution from the original 6 minutes to 1.5 minutes, synchronized with X-band radar. Subsequently, the optimal interpolation algorithm and pyramid transform algorithm are employed for spatial fusion of dual-band radar data, yielding the corresponding products SXnet-O and SXnet-K. Statistical analysis based on nearly 5,000 radar volume scanscases from the Guangdong-Hong Kong-Macao Greater Bay Area radar network during May–June 2022 demonstrates that the fused data achieve a 12% improvement in temporal correlation coefficient and a 28% reduction in root mean square error compared to the original X-band data. The spatial coverage reaches 96% of the union area of both radars, approximately 30% higher than that of a single radar. Comparative results indicate that SXnet-O significantly outperforms SXnet-K in system bias control (92% of deviations within ±2 dB), parameter consistency, and boundary stability. For data correction, SXnet-O reduces the deviation from the S-band reference by 5% compared to the original X-band data while effectively integrating the structural precision of X-band with the observational stability of S-band. This method provides a methodological foundation for data fusion applications in dense phased array weather radar networks.
Available online: May 18, 2026 , DOI: 10.7519/j.issn.1000-0526.2026.050703
Abstract:
Using station observation data and the NCEP/NCAR reanalysis data, this study analyzes the main climatic characteristics, large-scale atmospheric circulation anomalies, and East Asian winter monsoon features in China during the winter of 2025/2026, with a focus on the causes of the abnormally active dust weather in February. The results show that in the winter of 2025/2026, the average temperature was –1.5°C, which was 1.5°C higher than the climatological average, ranking as the second highest for the same period since 1961. The average precipitation was 27.4 mm, 35.3% below the climatological average, with a spatial distribution characterized by more precipitation in the north and less in the south. The 500 hPa geopotential height field over the mid–high latitudes of Eurasia were dominated by zonal circulation, with relatively straight westerly isohypses, and the East Asian winter monsoon intensity was weaker than normal. During the winter, a total of six dust weather processes affected China, which was 4.2 more than the climatological average (1.8). Among them, there were three dust storm processes, 2.7 more than the climatological average (0.3), and the number of dust days reached 7.7, the highest for winter since 1991. The cause analysis indicates that the dust source regions experienced significant warm and dry conditions, with below-average precipitation and above-average temperatures, leading to low vegetation coverage and a substantial reduction in surface resistance to wind erosion, thereby providing abundant material conditions for dust storms. Against this background, the synergistic effect of strong cold air and the Mongolian cyclone generated a large pressure gradient and triggered extreme gale winds, which, combined with enhanced thermal lifting due to large temperature differences between upper and lower levels, resulted in large a。mounts of dust being lifted into the atmosphere and transported downstream. Global climate warming has further exacerbated the drying trend in the dust source regions, increasing the frequency of the superposition of such warm-dry conditions
Using station observation data and the NCEP/NCAR reanalysis data, this study analyzes the main climatic characteristics, large-scale atmospheric circulation anomalies, and East Asian winter monsoon features in China during the winter of 2025/2026, with a focus on the causes of the abnormally active dust weather in February. The results show that in the winter of 2025/2026, the average temperature was –1.5°C, which was 1.5°C higher than the climatological average, ranking as the second highest for the same period since 1961. The average precipitation was 27.4 mm, 35.3% below the climatological average, with a spatial distribution characterized by more precipitation in the north and less in the south. The 500 hPa geopotential height field over the mid–high latitudes of Eurasia were dominated by zonal circulation, with relatively straight westerly isohypses, and the East Asian winter monsoon intensity was weaker than normal. During the winter, a total of six dust weather processes affected China, which was 4.2 more than the climatological average (1.8). Among them, there were three dust storm processes, 2.7 more than the climatological average (0.3), and the number of dust days reached 7.7, the highest for winter since 1991. The cause analysis indicates that the dust source regions experienced significant warm and dry conditions, with below-average precipitation and above-average temperatures, leading to low vegetation coverage and a substantial reduction in surface resistance to wind erosion, thereby providing abundant material conditions for dust storms. Against this background, the synergistic effect of strong cold air and the Mongolian cyclone generated a large pressure gradient and triggered extreme gale winds, which, combined with enhanced thermal lifting due to large temperature differences between upper and lower levels, resulted in large a。mounts of dust being lifted into the atmosphere and transported downstream. Global climate warming has further exacerbated the drying trend in the dust source regions, increasing the frequency of the superposition of such warm-dry conditions
Available online: April 27, 2026 , DOI: 10.7519/j.issn.1000-0526.2026.030401
Abstract:
Northern Ningxia is situated in the temperate continental climate zone of northwestern China, where complex topography and the climatological characteristics of warm-season convective storms (CS) remain not fully understood. This study utilizes CINRAD/CD radar products and sounding data from Yinchuan during May–September from 2011 to 2016 to investigate the climatological characteristics of CS in northern Ningxia under different prevailing wind directions at 500 hPa and 700 hPa. For the first time in this research domain, we present a comprehensive analysis integrating mean circulation patterns, convective environments, and CS intensity. Results demonstrate that solar radiative heating and topographic forcing from the Helan Mountains dominate the formation of CS climatological characteristics in northern Ningxia. Upon this foundation, dynamically varying prevailing winds induce more complex and diverse patterns in CS occurrence frequency, occurrence efficiency (defined as the ratio of CS occurrence frequency under a specific prevailing wind direction to the total frequency of that wind direction), diurnal variation, and spatial distribution. Notably, when southwesterly winds prevail at 500 hPa while easterly winds prevail at 700 hPa, the influence of prevailing winds becomes particularly pronounced. The mean 500 hPa circulation pattern associated with CS occurrence under a given prevailing wind direction characterizes the typical synoptic–scale systems and convective environments favorable for CS development under that flow regime, thereby directly determining CS occurrence efficiency and intensity. When northerly or northwesterly winds prevail at 500 hPa, northern Ningxia is positioned behind the trough, resulting in the lowest CS occurrence efficiency, the highest CAPE and CIN, and the strongest CS intensity. Under southerly or southwesterly wind regimes, the region is situated between the ridge and trough, where favorable moisture transport conditions lead to maximum CS occurrence efficiency; however, the minimal vertical temperature difference results in relatively weaker CS development. During prevailing westerly flows, the mid–latitude circulation exhibits zonal characteristics with frequent upstream shortwave trough activity, yielding intermediate levels of CS occurrence efficiency, CS intensity, and environmental parameters. At 700 hPa, differences in CS occurrence efficiency and intensity across various prevailing wind directions are relatively smaller, with CS intensity showing a strong correspondence to the vertical temperature gradient.
Northern Ningxia is situated in the temperate continental climate zone of northwestern China, where complex topography and the climatological characteristics of warm-season convective storms (CS) remain not fully understood. This study utilizes CINRAD/CD radar products and sounding data from Yinchuan during May–September from 2011 to 2016 to investigate the climatological characteristics of CS in northern Ningxia under different prevailing wind directions at 500 hPa and 700 hPa. For the first time in this research domain, we present a comprehensive analysis integrating mean circulation patterns, convective environments, and CS intensity. Results demonstrate that solar radiative heating and topographic forcing from the Helan Mountains dominate the formation of CS climatological characteristics in northern Ningxia. Upon this foundation, dynamically varying prevailing winds induce more complex and diverse patterns in CS occurrence frequency, occurrence efficiency (defined as the ratio of CS occurrence frequency under a specific prevailing wind direction to the total frequency of that wind direction), diurnal variation, and spatial distribution. Notably, when southwesterly winds prevail at 500 hPa while easterly winds prevail at 700 hPa, the influence of prevailing winds becomes particularly pronounced. The mean 500 hPa circulation pattern associated with CS occurrence under a given prevailing wind direction characterizes the typical synoptic–scale systems and convective environments favorable for CS development under that flow regime, thereby directly determining CS occurrence efficiency and intensity. When northerly or northwesterly winds prevail at 500 hPa, northern Ningxia is positioned behind the trough, resulting in the lowest CS occurrence efficiency, the highest CAPE and CIN, and the strongest CS intensity. Under southerly or southwesterly wind regimes, the region is situated between the ridge and trough, where favorable moisture transport conditions lead to maximum CS occurrence efficiency; however, the minimal vertical temperature difference results in relatively weaker CS development. During prevailing westerly flows, the mid–latitude circulation exhibits zonal characteristics with frequent upstream shortwave trough activity, yielding intermediate levels of CS occurrence efficiency, CS intensity, and environmental parameters. At 700 hPa, differences in CS occurrence efficiency and intensity across various prevailing wind directions are relatively smaller, with CS intensity showing a strong correspondence to the vertical temperature gradient.
Available online: April 24, 2026 , DOI: 10.7519/j.issn.1000-0526.2026.041701
Abstract:
Based on the precipitation data of 155 meteorological stations in the eastern part of Northwest China from 1961 to 2022, as well as historical datasets including global atmospheric data, sea surface temperature (SST), and sea ice data, this study integrates the Temporal Convolutional Network(TCN) module and the Convolutional Block Attention Module(CBAM) into the Long Short-Term Memory (LSTM) deep learning algorithm. A climate-smart prediction model for summer precipitation in the eastern part of Northwest China(named CBAM-TCN-LSTM) based on the fusion of deep learning algorithms was thereby established. The predictive performance of the model was verified, and its predictive capability was compared with that of multiple other deep learning algorithms.The results show that the intelligent prediction model based on the fusion of multiple deep learning algorithms outperforms single-algorithm deep learning models. During the independent sample validation period(2018–2022), the PS score for summer precipitation prediction ranged from 60% to 80%, with an average value of 73.8%.The Anomaly Correlation Coefficient (ACC) was positive for all years except 2020, with a mean value of 0.14, representing a significant improvement over other models. When compared with 7 current mainstream models (including machine learning algorithms, deep learning networks, and time-series networks), the CBAM-TCN-LSTM model exhibited superior performance across all five evaluation metrics: PS, PC, ACC, Mean Absolute Error (MAE), and Root Mean Square Error (RMSE). Furthermore, the CBAM-TCN-LSTM model was successfully applied in the 2023 flood season forecasting operation, accurately predicting the characteristic of below-normal summer precipitation in most areas of the eastern part of Northwest China, with a PS score of 90%.By building a precipitation prediction model that combines the TCN module and the CBAM module on the basis of the LSTM model (which has strong time-series predictive capability), this study provides a scientific basis and technical support for regional precipitation prediction, and the model holds good prospects for popularization and application.
Based on the precipitation data of 155 meteorological stations in the eastern part of Northwest China from 1961 to 2022, as well as historical datasets including global atmospheric data, sea surface temperature (SST), and sea ice data, this study integrates the Temporal Convolutional Network(TCN) module and the Convolutional Block Attention Module(CBAM) into the Long Short-Term Memory (LSTM) deep learning algorithm. A climate-smart prediction model for summer precipitation in the eastern part of Northwest China(named CBAM-TCN-LSTM) based on the fusion of deep learning algorithms was thereby established. The predictive performance of the model was verified, and its predictive capability was compared with that of multiple other deep learning algorithms.The results show that the intelligent prediction model based on the fusion of multiple deep learning algorithms outperforms single-algorithm deep learning models. During the independent sample validation period(2018–2022), the PS score for summer precipitation prediction ranged from 60% to 80%, with an average value of 73.8%.The Anomaly Correlation Coefficient (ACC) was positive for all years except 2020, with a mean value of 0.14, representing a significant improvement over other models. When compared with 7 current mainstream models (including machine learning algorithms, deep learning networks, and time-series networks), the CBAM-TCN-LSTM model exhibited superior performance across all five evaluation metrics: PS, PC, ACC, Mean Absolute Error (MAE), and Root Mean Square Error (RMSE). Furthermore, the CBAM-TCN-LSTM model was successfully applied in the 2023 flood season forecasting operation, accurately predicting the characteristic of below-normal summer precipitation in most areas of the eastern part of Northwest China, with a PS score of 90%.By building a precipitation prediction model that combines the TCN module and the CBAM module on the basis of the LSTM model (which has strong time-series predictive capability), this study provides a scientific basis and technical support for regional precipitation prediction, and the model holds good prospects for popularization and application.
Available online: April 18, 2026 , DOI: 10.7519/j.issn.1000-0526.2026.041601
Abstract:
Based on visibility observation, millimeter wave radar, EC reanalysis data, and wrfv4.2 version, IAP-LACS (3M), Morrison05 (2M) and Thompson 08 (2M) tests were designed for a high concentration, wide range and high impact sea fog process in April 2021. SW99 algorithm and FSL algorithm were used to diagnose and analyze visibility, and the following main conclusions were obtained: from April 1 to 2, 2021, 850hPa Zhejiang was between southwest wind and easterly shear. The southwest wind in the South was conducive to water vapor transport and the development of temperature ridge. There was an inversion layer near the surface along the coast. The junction is stable and the water vapor condition is good. In this process, the FSL algorithm diagnosis visibility results are obviously strong, and there is no gradient. SW99 algorithm is close to the actual situation in terms of intensity and range. The IAP-LACS (3M) of SW99 algorithm performs best in strength and range compared with the other two schemes. IAP-LACS (3M) better simulated the high value area of low-level cloud water content in Zhoushan and Taizhou Wenzhou coast, and better simulated the sea fog enhancement process along the coast of Sanshan gate from 22:00 on the 1st to 00:00 on the 2nd. The improvement of this scheme on the simulation of low-level cloud water content in the sea fog process is an important reason to improve the prediction effect of the sea fog. The comparative analysis of the three groups of schemes on the element simulation of Yuhuan station shows that the temperature simulation of 2m in the three groups of schemes from 12:00 to 16:00 on the 1st day is high, but the dew point temperature is close to the actual situation, so the relative humidity in the corresponding time is relatively small, which may be one of the reasons for the missing report of sea fog in Taizhou Wenzhou coastal area at the corresponding time. The IAP-LACS (3M) has the best temperature and dew point temperature simulation effect after 20:00 on the 1st day. In this process, IAP-LACS (3M) has a good matching relationship between the distribution of the high value area of numerical concentration output and the distribution of low visibility. At present, most cloud micro schemes do not output numerical concentration, and the droplet number concentration is an important parameter affecting visibility. IAP-LACS (3M) provides conditions for the introduction of numerical concentration into visibility diagnosis scheme.
Based on visibility observation, millimeter wave radar, EC reanalysis data, and wrfv4.2 version, IAP-LACS (3M), Morrison05 (2M) and Thompson 08 (2M) tests were designed for a high concentration, wide range and high impact sea fog process in April 2021. SW99 algorithm and FSL algorithm were used to diagnose and analyze visibility, and the following main conclusions were obtained: from April 1 to 2, 2021, 850hPa Zhejiang was between southwest wind and easterly shear. The southwest wind in the South was conducive to water vapor transport and the development of temperature ridge. There was an inversion layer near the surface along the coast. The junction is stable and the water vapor condition is good. In this process, the FSL algorithm diagnosis visibility results are obviously strong, and there is no gradient. SW99 algorithm is close to the actual situation in terms of intensity and range. The IAP-LACS (3M) of SW99 algorithm performs best in strength and range compared with the other two schemes. IAP-LACS (3M) better simulated the high value area of low-level cloud water content in Zhoushan and Taizhou Wenzhou coast, and better simulated the sea fog enhancement process along the coast of Sanshan gate from 22:00 on the 1st to 00:00 on the 2nd. The improvement of this scheme on the simulation of low-level cloud water content in the sea fog process is an important reason to improve the prediction effect of the sea fog. The comparative analysis of the three groups of schemes on the element simulation of Yuhuan station shows that the temperature simulation of 2m in the three groups of schemes from 12:00 to 16:00 on the 1st day is high, but the dew point temperature is close to the actual situation, so the relative humidity in the corresponding time is relatively small, which may be one of the reasons for the missing report of sea fog in Taizhou Wenzhou coastal area at the corresponding time. The IAP-LACS (3M) has the best temperature and dew point temperature simulation effect after 20:00 on the 1st day. In this process, IAP-LACS (3M) has a good matching relationship between the distribution of the high value area of numerical concentration output and the distribution of low visibility. At present, most cloud micro schemes do not output numerical concentration, and the droplet number concentration is an important parameter affecting visibility. IAP-LACS (3M) provides conditions for the introduction of numerical concentration into visibility diagnosis scheme.
Available online: April 17, 2026 , DOI: 10.7519/j.issn.1000-0526.2025.100701
Abstract:
Using conventional observation data and Suizhou S-band dual polarization weather radar observation data, short-time heavy rain is classified into strong weather scale system forcing type (referred to as "strong forcing type") and weak weather scale system forcing type (referred to as "weak forcing type") according to the weather circulation pattern. The distribution characteristics and dual polarization radar echo characteristics of the two types are compared and analyzed.The results show that:(1)Strong forcing type have more occurrences, wider ranges, more stations, and longer durations.(2)In the strong forcing type, July has the highest frequency, followed by June, and the lowest in August. Dahong Mountain and Tongbai Mountain being the most frequent areas.The daily variation characteristics show a three peak distribution, with the highest occurrence occurring from 05:00 to 08:00, followed by 23:00 to 00:00, and the third occurring around 15:00. In the weak forcing type, the frequency of occurrence is basically the same in July and August, with the least in June. The distribution of high-frequency areas is scattered, but mountainous areas are still high-frequency areas. The daily variation follows a unimodal distribution, with the peak occurring at 15:00.(3)Both two types have the characteristics of higher rainfall intensity, stronger echo intensity, higher concentration of liquid particles, higher echo top, larger diameter of liquid particles. (4)In the same rainfall intensity level, there is no significant difference in the combined combined reflectivity(CR), 1 km horizontal reflectivity(Zh), and echo top height (ET) of two types of short-term heavy precipitation, and they all have low centroid characteristics, with the strong forcing type having more obvious low centroid characteristics. However, the interval and average values of the 1 km differential reflectivity(Zdr) and specific differential phase (Kdp) for the strong forcing type are significantly smaller than those for the weak forcing type, while the interval and average values of the 1 km correlation coefficient(CC) are slightly larger than those for the weak forcing type. This indicates that the weak forcing type has larger particle diameters in the lower layers and is more prone to incomplete melting of ice phase particles in the lower layers.
Using conventional observation data and Suizhou S-band dual polarization weather radar observation data, short-time heavy rain is classified into strong weather scale system forcing type (referred to as "strong forcing type") and weak weather scale system forcing type (referred to as "weak forcing type") according to the weather circulation pattern. The distribution characteristics and dual polarization radar echo characteristics of the two types are compared and analyzed.The results show that:(1)Strong forcing type have more occurrences, wider ranges, more stations, and longer durations.(2)In the strong forcing type, July has the highest frequency, followed by June, and the lowest in August. Dahong Mountain and Tongbai Mountain being the most frequent areas.The daily variation characteristics show a three peak distribution, with the highest occurrence occurring from 05:00 to 08:00, followed by 23:00 to 00:00, and the third occurring around 15:00. In the weak forcing type, the frequency of occurrence is basically the same in July and August, with the least in June. The distribution of high-frequency areas is scattered, but mountainous areas are still high-frequency areas. The daily variation follows a unimodal distribution, with the peak occurring at 15:00.(3)Both two types have the characteristics of higher rainfall intensity, stronger echo intensity, higher concentration of liquid particles, higher echo top, larger diameter of liquid particles. (4)In the same rainfall intensity level, there is no significant difference in the combined combined reflectivity(CR), 1 km horizontal reflectivity(Zh), and echo top height (ET) of two types of short-term heavy precipitation, and they all have low centroid characteristics, with the strong forcing type having more obvious low centroid characteristics. However, the interval and average values of the 1 km differential reflectivity(Zdr) and specific differential phase (Kdp) for the strong forcing type are significantly smaller than those for the weak forcing type, while the interval and average values of the 1 km correlation coefficient(CC) are slightly larger than those for the weak forcing type. This indicates that the weak forcing type has larger particle diameters in the lower layers and is more prone to incomplete melting of ice phase particles in the lower layers.
Available online: April 15, 2026 , DOI: 10.7519/j.issn.1000-0526.2025.082001
Abstract:
Based on rice phenological stages and meteorological observations from nationwide single-season and double-season rice regions, combined with major agro-meteorological disaster indicators, disaster intensity and hazard indices were constructed to analyze the changing characteristics of heat stress, cold stress, drought, and compound heat and drought stresses from 1991 to 2024. The results indicate that in the period of 1991-2024, heat stress in single-season rice has significantly intensified, with the peak observed in 2022 while the area percentage exposed to heat stress. Meanwhile, early rice heat stress has shown fluctuating changes and has been gradually increasing since 2017. Obstruction-type chilling injury in rice in Northeast China has been weakened, while it weakens after 2017 and merely occurs in recent two years. The intensity of cold dew wind in late rice has been stronger after 2017 and peaked in 2020 after that it decresed. Drought has exhibited large fluctuations, with the most severe conditions occurring in single-season and late rice in 2022, and the area percentage exposed to drought in single-season ric and late rice is higher than that in early rice. The compound heat and drought stresses in single-season rice has been more severe than in early rice. At the spatial scale, areas for severer heat stress in single-season rice have been concentrated in northeastern Sichuan, central Chongqing, and eastern Hubei, while for early rice, they have been located in southeastern Hunan central Zhejiang, central-southern Jiangxi, and central Fujian where the heat stress intend to intensify. The obstruction-type chilling injury in Northeast China have been identified from southwest to northeast, and cold dew wind for late rice tends to increase from south to north. The drought in single-season rice is severe in Northeast China in comparison with that in southern areas, and that in early rice decreases from south to north which is opposite in late rice. High intensity for compound heat and drought stresses in single-season rice have been concentrated in northeastern Sichuan, central Chongqing, eastern Hubei and western Hunan, while for early rice, they have been located in northern Zhejiang and southeastern Jiangxi. In these areas exposed to high intensity of disasters, the hazard is generally heavy, which can help guide for taking prevention of specific disasters. Keywords: rice, heat stress, cold stress, drought, combined disaster, intensity index
Based on rice phenological stages and meteorological observations from nationwide single-season and double-season rice regions, combined with major agro-meteorological disaster indicators, disaster intensity and hazard indices were constructed to analyze the changing characteristics of heat stress, cold stress, drought, and compound heat and drought stresses from 1991 to 2024. The results indicate that in the period of 1991-2024, heat stress in single-season rice has significantly intensified, with the peak observed in 2022 while the area percentage exposed to heat stress. Meanwhile, early rice heat stress has shown fluctuating changes and has been gradually increasing since 2017. Obstruction-type chilling injury in rice in Northeast China has been weakened, while it weakens after 2017 and merely occurs in recent two years. The intensity of cold dew wind in late rice has been stronger after 2017 and peaked in 2020 after that it decresed. Drought has exhibited large fluctuations, with the most severe conditions occurring in single-season and late rice in 2022, and the area percentage exposed to drought in single-season ric and late rice is higher than that in early rice. The compound heat and drought stresses in single-season rice has been more severe than in early rice. At the spatial scale, areas for severer heat stress in single-season rice have been concentrated in northeastern Sichuan, central Chongqing, and eastern Hubei, while for early rice, they have been located in southeastern Hunan central Zhejiang, central-southern Jiangxi, and central Fujian where the heat stress intend to intensify. The obstruction-type chilling injury in Northeast China have been identified from southwest to northeast, and cold dew wind for late rice tends to increase from south to north. The drought in single-season rice is severe in Northeast China in comparison with that in southern areas, and that in early rice decreases from south to north which is opposite in late rice. High intensity for compound heat and drought stresses in single-season rice have been concentrated in northeastern Sichuan, central Chongqing, eastern Hubei and western Hunan, while for early rice, they have been located in northern Zhejiang and southeastern Jiangxi. In these areas exposed to high intensity of disasters, the hazard is generally heavy, which can help guide for taking prevention of specific disasters. Keywords: rice, heat stress, cold stress, drought, combined disaster, intensity index
Available online: April 03, 2026 , DOI: 10.7519/j.issn.1000-0526.2026.040201
Abstract:
The persistent drought event cross the winter and spring in Yunnan (YN-WSPDE) have a significant impact on the planting of major autumn crops and the safety of people"s life and property, and it is of great scientific significance for meteorological disaster prevention and reduction to investigate the change and cause of this events. As a fundamental part of the research on YN-WSPDE, how to define the YN-WSPDE standard is studied based on daily precipitation and temperature observation data of 125 stations in Yunnan from 1961 to 2024, as well as the NCEP/NCAR daily reanalysis atmospheric circulation data during the same period. By analyzing the spatiotemporal characteristics of drought in winter and spring in Yunnan, it was found that the drought distribution in Yunnan is characterized by less in the east and more in the west, and more in the north and less in the south. The regions with the highest drought occurrence are mainly concentrated in the eastern part of northwest Yunnan, including Lijiang, Dali, and northern Chuxiong, while the southern parts of Honghe and Xishuangbanna have less drought occurrence. The WSPDEs standard for single station and provincial region in Yunnan are defined as: the station standard refers to the occurrence of light or above level drought in both winter and spring in a year, with moderate or above level drought occurring in one of the seasons. When 25 stations (1/5 of the total number of stations in the Yunnan) experience the WSPDE in a year, and the average precipitation anomaly percentage in both winter and spring is ≤-10%, it is defined as a WSPDE in provincial area. Preliminary analysis results show that the continuously anomalous geopotential height difference at 500-hPa between the north and south in the Eastern of East Asia, as well as anomalous anticyclone at 700-hPa over the Bay of Bengal basin, have a significant impact on the YN-WSPDE.
The persistent drought event cross the winter and spring in Yunnan (YN-WSPDE) have a significant impact on the planting of major autumn crops and the safety of people"s life and property, and it is of great scientific significance for meteorological disaster prevention and reduction to investigate the change and cause of this events. As a fundamental part of the research on YN-WSPDE, how to define the YN-WSPDE standard is studied based on daily precipitation and temperature observation data of 125 stations in Yunnan from 1961 to 2024, as well as the NCEP/NCAR daily reanalysis atmospheric circulation data during the same period. By analyzing the spatiotemporal characteristics of drought in winter and spring in Yunnan, it was found that the drought distribution in Yunnan is characterized by less in the east and more in the west, and more in the north and less in the south. The regions with the highest drought occurrence are mainly concentrated in the eastern part of northwest Yunnan, including Lijiang, Dali, and northern Chuxiong, while the southern parts of Honghe and Xishuangbanna have less drought occurrence. The WSPDEs standard for single station and provincial region in Yunnan are defined as: the station standard refers to the occurrence of light or above level drought in both winter and spring in a year, with moderate or above level drought occurring in one of the seasons. When 25 stations (1/5 of the total number of stations in the Yunnan) experience the WSPDE in a year, and the average precipitation anomaly percentage in both winter and spring is ≤-10%, it is defined as a WSPDE in provincial area. Preliminary analysis results show that the continuously anomalous geopotential height difference at 500-hPa between the north and south in the Eastern of East Asia, as well as anomalous anticyclone at 700-hPa over the Bay of Bengal basin, have a significant impact on the YN-WSPDE.
Available online: March 10, 2026 , DOI: 10.7519/j.issn.1000-0526.2026.011201
Abstract:
Abstract:On 17th (hereinafter referred to as “1217”)and from 24th to 26th December 2021 (hereinafter referred to as “1225”), Shandong Peninsula experienced two Bohai sea-effect snowfall events.Compared with “1217”,the cold air intensity was stronger and snowfall duration was longer for “1225”, but the total snowfall amount was less and intensity of snowfall was weaker than “1217”. In order to clarify the reasons, thermodynamic and dynamical characters were analyzed and compared by using data of moored buoy station,S-band Doppler weather radar,conventional sounding, hourly snowfall observation data from ground automatic meteorological stations and ERA5( ECMWF Reanalysis v5). The main results are as follows:During the first snowfall phase of "1225", sea-air temperature difference(temperature difference between sea surface and 850hPa air) was 28°C, which exceeded "1217" (24°C). During the second snowfall phase, both events exhibited comparable sea-air temperature between 24°C and 25°C. However, throughout the snowfall period,"1225" displayed an?intermittent weakening of low-level cold advection, with?advection intensities consistently weaker than "1217". This weaker thermal advection?impaired the development of?lower-level thermal and moisture conditions?for the "1225". During "1217", the intense core of cold advection extended vertically to 700～500 hPa, whereas during "1225" it was confined to 875～750 hPa and was weaker than"1217". Consequently, the inversion layer developed above the cold advection center in "1225" displayed both lower height and reduced thickness relative to "1217". This structural difference further suppressed depth of the conditionally unstable (or neutral) layer beneath the inversion,thereby limiting the vertical extent of shallow convective clouds and ultimately diminishing snowfall intensity. During the second snowfall phase of "1225", steering wind direction (mean wind direction from 1000 hPa to 700 hPa) over the Bohai Sea and its upstream regions was 327°, deviating by 11° from "1217" with a larger westerly component. Consequently, the low-level tongue, mesoscale shear line and heavy snow echo band all displayed larger zonal component and positioned predominantly offshore resulting in inconspicuous snowfall over the peninsula ultimately. Cold advection constitutes a primary physical driver modulating the thermal structure of sea-effect snowfall. Simultaneously, it indirectly governs the initiation and evolution of mesoscale shear lines by inducing a low-level warm tongue, thereby providing dynamical lifting and organizational mechanism over snowfall echo structures,ultimately shaping the dynamical structure of snowfall. For forecasting applications, it is essential to make an integrated dynamic analysis of cold advection developmental stages, three-dimensional spatial structure and intensity evolution on low-level. Focus on sea-air temperature difference,absolute moisture content within the boundary layer, inversion layer height, thickness of the conditionally(or neutral) unstablelayer and steering wind direction. Diagnostics of mesoscale characteristics such as the position, orientation and intensity of low-level warm tongue and shear line are imperative.
Abstract:On 17th (hereinafter referred to as “1217”)and from 24th to 26th December 2021 (hereinafter referred to as “1225”), Shandong Peninsula experienced two Bohai sea-effect snowfall events.Compared with “1217”,the cold air intensity was stronger and snowfall duration was longer for “1225”, but the total snowfall amount was less and intensity of snowfall was weaker than “1217”. In order to clarify the reasons, thermodynamic and dynamical characters were analyzed and compared by using data of moored buoy station,S-band Doppler weather radar,conventional sounding, hourly snowfall observation data from ground automatic meteorological stations and ERA5( ECMWF Reanalysis v5). The main results are as follows:During the first snowfall phase of "1225", sea-air temperature difference(temperature difference between sea surface and 850hPa air) was 28°C, which exceeded "1217" (24°C). During the second snowfall phase, both events exhibited comparable sea-air temperature between 24°C and 25°C. However, throughout the snowfall period,"1225" displayed an?intermittent weakening of low-level cold advection, with?advection intensities consistently weaker than "1217". This weaker thermal advection?impaired the development of?lower-level thermal and moisture conditions?for the "1225". During "1217", the intense core of cold advection extended vertically to 700～500 hPa, whereas during "1225" it was confined to 875～750 hPa and was weaker than"1217". Consequently, the inversion layer developed above the cold advection center in "1225" displayed both lower height and reduced thickness relative to "1217". This structural difference further suppressed depth of the conditionally unstable (or neutral) layer beneath the inversion,thereby limiting the vertical extent of shallow convective clouds and ultimately diminishing snowfall intensity. During the second snowfall phase of "1225", steering wind direction (mean wind direction from 1000 hPa to 700 hPa) over the Bohai Sea and its upstream regions was 327°, deviating by 11° from "1217" with a larger westerly component. Consequently, the low-level tongue, mesoscale shear line and heavy snow echo band all displayed larger zonal component and positioned predominantly offshore resulting in inconspicuous snowfall over the peninsula ultimately. Cold advection constitutes a primary physical driver modulating the thermal structure of sea-effect snowfall. Simultaneously, it indirectly governs the initiation and evolution of mesoscale shear lines by inducing a low-level warm tongue, thereby providing dynamical lifting and organizational mechanism over snowfall echo structures,ultimately shaping the dynamical structure of snowfall. For forecasting applications, it is essential to make an integrated dynamic analysis of cold advection developmental stages, three-dimensional spatial structure and intensity evolution on low-level. Focus on sea-air temperature difference,absolute moisture content within the boundary layer, inversion layer height, thickness of the conditionally(or neutral) unstablelayer and steering wind direction. Diagnostics of mesoscale characteristics such as the position, orientation and intensity of low-level warm tongue and shear line are imperative.
Available online: February 10, 2026 , DOI: 10.7519/j.issn.1000-0526.2025.080501
Abstract:
A rare weather event featuring a long-lived period of freezing rain and ice pellets transitioning to snow occurred in the southern Shandong region from February 20-21, 2024. Using conventional observational data, wind profiler radar data, raindrop spectrum data, and ERA5 reanalysis data to analyze this event, the results indicate:?(1)? The event was characterized by return flow precipitation. A southwest warm and humid airflow ahead of the upper-level trough slid upwards along a cold pad caused by a significant temperature drop due to the low-level strong cold air. The interaction between the mid-level warm and humid airflow and the low-level northeastern airflow formed a strong inversion, and the "cold-warm-cold" vertical temperature structure was maintained for a long time, leading to a 12-hour period of freezing rain and ice pellets??(2)? Both freezing rain and ice pellets exhibit typical characteristics of ice-phase melting. The ground temperature during freezing rain is higher, the starting height of the warm layer is lower, and both the thickness and intensity of the warm layer are greater, while the thickness and intensity of the cold layer are smaller. ??(3)? Raindrop spectrum data showed no significant differences in the particle size distribution characteristics between freezing rain and ice pellets. Both had features of small particle size, low number concentration, low precipitation intensity, and high falling speed. The velocity curves of both were similar to those of rainfall but with slight differences. Freezing rain had slightly larger particles and fewer particle numbers than ice pellets. During the snowfall phase, the spectrum widened, characterized by large particle size, high number concentration, high precipitation intensity, and low falling speed.
A rare weather event featuring a long-lived period of freezing rain and ice pellets transitioning to snow occurred in the southern Shandong region from February 20-21, 2024. Using conventional observational data, wind profiler radar data, raindrop spectrum data, and ERA5 reanalysis data to analyze this event, the results indicate:?(1)? The event was characterized by return flow precipitation. A southwest warm and humid airflow ahead of the upper-level trough slid upwards along a cold pad caused by a significant temperature drop due to the low-level strong cold air. The interaction between the mid-level warm and humid airflow and the low-level northeastern airflow formed a strong inversion, and the "cold-warm-cold" vertical temperature structure was maintained for a long time, leading to a 12-hour period of freezing rain and ice pellets??(2)? Both freezing rain and ice pellets exhibit typical characteristics of ice-phase melting. The ground temperature during freezing rain is higher, the starting height of the warm layer is lower, and both the thickness and intensity of the warm layer are greater, while the thickness and intensity of the cold layer are smaller. ??(3)? Raindrop spectrum data showed no significant differences in the particle size distribution characteristics between freezing rain and ice pellets. Both had features of small particle size, low number concentration, low precipitation intensity, and high falling speed. The velocity curves of both were similar to those of rainfall but with slight differences. Freezing rain had slightly larger particles and fewer particle numbers than ice pellets. During the snowfall phase, the spectrum widened, characterized by large particle size, high number concentration, high precipitation intensity, and low falling speed.
Available online: February 03, 2026 , DOI: 10.7519/j.issn.1000-0526.2025.072402
Abstract:
The complex topography of the hilly and mountainous regions in Fujian Province gives rise to diverse hail cloud structures, notably isolated convective cells and squall lines. This study addresses the lack of comparative research on the microphysical characteristics of these two types of hail-bearing convection. Based on a persistent severe convective event that occurred in March 2023 over the hilly terrain of southeastern coastal China, S-band dual-polarization radar data and surface precipitation particle spectra observations are employed to comparatively analyze the ground-based spectral characteristics of precipitation particles associated with isolated cells and squall-line systems.The results show that isolated convection during the concentrated hailfall stage exhibits larger particle sizes, more complex spectral structures, more pronounced fluctuations in total particle number concentration, and greater dispersion in the velocity–size spectra, indicating more vigorous ice-phase microphysical processes. In contrast, squall-line convection is characterized by high-density hail, a relatively high concentration of small raindrops, and simpler spectral structures. For both convective types, the peak in precipitation particle concentration appears near the front side of the cloud system in the heavy rainfall region following the main hailfall stage, accompanied by a narrowing of the spectral width and a reduction in large particles. The precipitation process is further divided into four distinct stages, each exhibiting markedly different spectral characteristics.These findings enhance the understanding of the microphysical processes of isolated and squall-line hail clouds and provide scientific support for short-term nowcasting and hail suppression operations.
The complex topography of the hilly and mountainous regions in Fujian Province gives rise to diverse hail cloud structures, notably isolated convective cells and squall lines. This study addresses the lack of comparative research on the microphysical characteristics of these two types of hail-bearing convection. Based on a persistent severe convective event that occurred in March 2023 over the hilly terrain of southeastern coastal China, S-band dual-polarization radar data and surface precipitation particle spectra observations are employed to comparatively analyze the ground-based spectral characteristics of precipitation particles associated with isolated cells and squall-line systems.The results show that isolated convection during the concentrated hailfall stage exhibits larger particle sizes, more complex spectral structures, more pronounced fluctuations in total particle number concentration, and greater dispersion in the velocity–size spectra, indicating more vigorous ice-phase microphysical processes. In contrast, squall-line convection is characterized by high-density hail, a relatively high concentration of small raindrops, and simpler spectral structures. For both convective types, the peak in precipitation particle concentration appears near the front side of the cloud system in the heavy rainfall region following the main hailfall stage, accompanied by a narrowing of the spectral width and a reduction in large particles. The precipitation process is further divided into four distinct stages, each exhibiting markedly different spectral characteristics.These findings enhance the understanding of the microphysical processes of isolated and squall-line hail clouds and provide scientific support for short-term nowcasting and hail suppression operations.
Available online: January 23, 2026 , DOI: 10.7519/j.issn.1000-0526.2026.010602
Abstract:
This study is based on LiDAR wind profiler data and uses the Wind Profile Exponent (WPE) method to calculate the wind profile exponent within the 50–500 meter height range under different surface wind conditions. The results were validated using data from 50 meteorological stations, each with observation heights exceeding 40 meters. The findings indicate that the LiDAR wind profile exponent suffers from a systematic overestimation, with errors closely related to the building density and height characteristics of the observation area. To address this issue, the study innovatively introduces urban building parameters and proposes a multi-factor-driven dynamic correction algorithm for the wind profile exponent, overcoming the limitations of the traditional single roughness parameter approach. After correction, 91.7% of the wind speed calculation errors were controlled within a ±1 Beaufort scale range, with 50.1% showing zero error. Building upon this, a three-dimensional high-altitude wind field reconstruction model tailored for urban complex building environments was further developed. This model has a horizontal resolution of 100 meters and vertical coverage from 50 to 500 meters, enabling real-time monitoring every 5 minutes and forecast outputs up to 168 hours. The model provides a low-cost, high-precision wind disaster prevention and control technology pathway for urban high-altitude operations, offering significant business application potential and engineering value.
This study is based on LiDAR wind profiler data and uses the Wind Profile Exponent (WPE) method to calculate the wind profile exponent within the 50–500 meter height range under different surface wind conditions. The results were validated using data from 50 meteorological stations, each with observation heights exceeding 40 meters. The findings indicate that the LiDAR wind profile exponent suffers from a systematic overestimation, with errors closely related to the building density and height characteristics of the observation area. To address this issue, the study innovatively introduces urban building parameters and proposes a multi-factor-driven dynamic correction algorithm for the wind profile exponent, overcoming the limitations of the traditional single roughness parameter approach. After correction, 91.7% of the wind speed calculation errors were controlled within a ±1 Beaufort scale range, with 50.1% showing zero error. Building upon this, a three-dimensional high-altitude wind field reconstruction model tailored for urban complex building environments was further developed. This model has a horizontal resolution of 100 meters and vertical coverage from 50 to 500 meters, enabling real-time monitoring every 5 minutes and forecast outputs up to 168 hours. The model provides a low-cost, high-precision wind disaster prevention and control technology pathway for urban high-altitude operations, offering significant business application potential and engineering value.
Available online: January 21, 2026 , DOI: 10.7519/j.issn.1000-0526.2026.011602
Abstract:
Fixed-hourly precipitation data may underestimate the characteristics of heavy rainfall at the hourly scale. To gain a deeper understanding of the variation patterns of hourly heavy rainfall, this study utilizes minute-level precipitation observations from 123 national meteorological stations in Shandong Province from June to September during the flood seasons of 2004–2024. It compares the differences between the 60-minute sliding window and fixed-hourly statistical methods in identifying heavy rainfall events, aiming to quantitatively assess the impact of different methods on the frequency, intensity, and spatio-temporal distribution of heavy rainfall. The results indicate that the 60-minute sliding window method captures heavy rainfall events more comprehensively than the fixed-hourly method. The average frequency of heavy rainfall across the province was 124.3 times using the sliding method, which is 1.48 times that of the fixed-hourly method (84.3 times), with regional ratios ranging between 1.31 and 1.81. The maximum precipitation captured by the sliding method was on average 10.0 mm higher, exceeding 30.0 mm at some stations. While the spatial distributions of the two methods are generally consistent, the sliding method exhibits greater spatial variability and extremity. It also more clearly reveals increasing trends in both the frequency and intensity of heavy rainfall, with climatic tendency rates of 1.31 times·(10a)?1 and 4.514 mm·(10a)?1, respectively. Moreover, monthly and diurnal variation characteristics are more distinct with the sliding method, particularly during the high-frequency periods from July to August and from afternoon to early morning. The traditional fixed-hourly statistical system underestimates the frequency and extreme intensity of short-duration heavy rainfall. The 60-minute sliding window method provides a more accurate representation of heavy rainfall characteristics, offering important applications for improving the accuracy of storm monitoring and enhancing early warning capabilities for disaster risk.
Fixed-hourly precipitation data may underestimate the characteristics of heavy rainfall at the hourly scale. To gain a deeper understanding of the variation patterns of hourly heavy rainfall, this study utilizes minute-level precipitation observations from 123 national meteorological stations in Shandong Province from June to September during the flood seasons of 2004–2024. It compares the differences between the 60-minute sliding window and fixed-hourly statistical methods in identifying heavy rainfall events, aiming to quantitatively assess the impact of different methods on the frequency, intensity, and spatio-temporal distribution of heavy rainfall. The results indicate that the 60-minute sliding window method captures heavy rainfall events more comprehensively than the fixed-hourly method. The average frequency of heavy rainfall across the province was 124.3 times using the sliding method, which is 1.48 times that of the fixed-hourly method (84.3 times), with regional ratios ranging between 1.31 and 1.81. The maximum precipitation captured by the sliding method was on average 10.0 mm higher, exceeding 30.0 mm at some stations. While the spatial distributions of the two methods are generally consistent, the sliding method exhibits greater spatial variability and extremity. It also more clearly reveals increasing trends in both the frequency and intensity of heavy rainfall, with climatic tendency rates of 1.31 times·(10a)?1 and 4.514 mm·(10a)?1, respectively. Moreover, monthly and diurnal variation characteristics are more distinct with the sliding method, particularly during the high-frequency periods from July to August and from afternoon to early morning. The traditional fixed-hourly statistical system underestimates the frequency and extreme intensity of short-duration heavy rainfall. The 60-minute sliding window method provides a more accurate representation of heavy rainfall characteristics, offering important applications for improving the accuracy of storm monitoring and enhancing early warning capabilities for disaster risk.
Available online: January 06, 2026 , DOI: 10.7519/j.issn.1000-0526.2025.072803
Abstract:
Based on the operational real-time typhoon data of National Meteorological Centre and other sources of observations including the ERA5 reanalysis data from the European Centre for Medium-Range Weather Forecasting, we analyzed the characteristics of typhoon activities in western North Pacific in 2024. We revealed the different features of typhoons between summer and autumn in 2024 from three aspects: typhoon genesis, typhoon activity, and typhoon landfall. In the summer of 2024, the typhoons genesis number was lower than normal, with the genesis region shifted northward and eastward, and weaker maximum intensities. No typhoons were generated from June 1 to July 18, while the peak summer season saw frequent typhoon occurrences, mostly following northwestward and northward tracks. The number of typhoons landing in China was less than usual, with weaker landfall intensities. However, typhoons were more active in autumn. The typhoon genesis number ranked the third highest in history, with their genesis location shifting northward and westward, and their intensities being unusually strong. Typhoon activities were characterized by distinct periodicity and clustering, with most following westward or northwestward tracks. The number of typhoon landfalls was relatively higher, and the landfall intensities were stronger than the average. Further research showed that the significant differences between summer and autumn typhoons in 2024 were closely related to multiple factors such as the lag effect of sea surface temperature in the year following El Ni?o, the abnormal Western Pacific subtropical high, the phase transition of the tropical intraseasonal oscillation, the onset and withdrawal of the South China Sea summer monsoon, etc.
Based on the operational real-time typhoon data of National Meteorological Centre and other sources of observations including the ERA5 reanalysis data from the European Centre for Medium-Range Weather Forecasting, we analyzed the characteristics of typhoon activities in western North Pacific in 2024. We revealed the different features of typhoons between summer and autumn in 2024 from three aspects: typhoon genesis, typhoon activity, and typhoon landfall. In the summer of 2024, the typhoons genesis number was lower than normal, with the genesis region shifted northward and eastward, and weaker maximum intensities. No typhoons were generated from June 1 to July 18, while the peak summer season saw frequent typhoon occurrences, mostly following northwestward and northward tracks. The number of typhoons landing in China was less than usual, with weaker landfall intensities. However, typhoons were more active in autumn. The typhoon genesis number ranked the third highest in history, with their genesis location shifting northward and westward, and their intensities being unusually strong. Typhoon activities were characterized by distinct periodicity and clustering, with most following westward or northwestward tracks. The number of typhoon landfalls was relatively higher, and the landfall intensities were stronger than the average. Further research showed that the significant differences between summer and autumn typhoons in 2024 were closely related to multiple factors such as the lag effect of sea surface temperature in the year following El Ni?o, the abnormal Western Pacific subtropical high, the phase transition of the tropical intraseasonal oscillation, the onset and withdrawal of the South China Sea summer monsoon, etc.
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2012,38(12):1482-1491, DOI: 10.7519/j.issn.1000-0526.2012.12.005
Abstract:
By using the conventional meteorological data, Doppler radar data and NCEP/NCAR reanalysis data, the characteristics of Doppler radar’s reflectivity, environmental condition and trigger mechanism of the heavy rain are analyzed and compared between two abrupt heavy rain processes occurring in Sichuan Basin on 3 July (7.3) and 23 July (7.23) 2011. The results show that: the “7.3” heavy rain happened under a typical circulation background, and moisture transporting to the heavy rain area from the South China Sea was smoothly, thus the heavy rainfall maintained so long, but the “7.23” heavy rain occurred behind the upper cold vortex, and convective unstable energy was abundant and vertical wind shear was strong, thus this heavy rain process happened with hail and thunderstorm weather accompanied, its radar reflectivity was 5 dBz stronger than “7.3” case and had the characteristics of severe storms such as the low level weak reflectivity and the upper echo overhang. As a whole, the non equilibrium force is contributed to the occurrence of heavy rain and it is the excited mechanism of the two heavy rainfalls, and the change of the divergence evolvement is consistent with the strength and the position of the heavy rain which would happen 6 hours later．
By using the conventional meteorological data, Doppler radar data and NCEP/NCAR reanalysis data, the characteristics of Doppler radar’s reflectivity, environmental condition and trigger mechanism of the heavy rain are analyzed and compared between two abrupt heavy rain processes occurring in Sichuan Basin on 3 July (7.3) and 23 July (7.23) 2011. The results show that: the “7.3” heavy rain happened under a typical circulation background, and moisture transporting to the heavy rain area from the South China Sea was smoothly, thus the heavy rainfall maintained so long, but the “7.23” heavy rain occurred behind the upper cold vortex, and convective unstable energy was abundant and vertical wind shear was strong, thus this heavy rain process happened with hail and thunderstorm weather accompanied, its radar reflectivity was 5 dBz stronger than “7.3” case and had the characteristics of severe storms such as the low level weak reflectivity and the upper echo overhang. As a whole, the non equilibrium force is contributed to the occurrence of heavy rain and it is the excited mechanism of the two heavy rainfalls, and the change of the divergence evolvement is consistent with the strength and the position of the heavy rain which would happen 6 hours later．
2017,43(7):769-780, DOI: 10.7519/j.issn.1000-0526.2017.07.001
Abstract:
The spatial distributions of severe convective wind (SCW) and nonsevere thunderstorms (NT) over South China, occurring between 08:00 BT and 20:00 BT during spring and summer in 2010-2014, were analyzed by using the observational data from China Meteorological Administration. And then, their environmental characteristics were compared between SCW and NT in spring and summer. It was found that SCW in summer is more frequently than that in spring and that NT in summer is about 3.6 times the counts of NT in spring. SCW events mainly concentrate in the western Guangdong to the Pearl River Delta Region. Compared to NT, SCW is generally associated with stronger baroclinity, instability and stronger dynamic forcing. The precipitable water and averaged relative humidity between 700-500 hPa of SCW tend to be higher than those of NT in spring, while the opposite is the case for the pattern in summer. In conclusion, it is obvious that the dynamic forcing for SCW in spring is much better than these in summer, while the thermal condition is more significant in summer.
The spatial distributions of severe convective wind (SCW) and nonsevere thunderstorms (NT) over South China, occurring between 08:00 BT and 20:00 BT during spring and summer in 2010-2014, were analyzed by using the observational data from China Meteorological Administration. And then, their environmental characteristics were compared between SCW and NT in spring and summer. It was found that SCW in summer is more frequently than that in spring and that NT in summer is about 3.6 times the counts of NT in spring. SCW events mainly concentrate in the western Guangdong to the Pearl River Delta Region. Compared to NT, SCW is generally associated with stronger baroclinity, instability and stronger dynamic forcing. The precipitable water and averaged relative humidity between 700-500 hPa of SCW tend to be higher than those of NT in spring, while the opposite is the case for the pattern in summer. In conclusion, it is obvious that the dynamic forcing for SCW in spring is much better than these in summer, while the thermal condition is more significant in summer.
2010,36(3):9-18, DOI: 10.7519/j.issn.1000-0526.2010.3.002
Abstract:
Potential vorticity (PV) is one of the important concepts in advanced synoptic and dynamic meteorology. This paper is a brief introduction to the theory of potential vorticity, including the concept of PV, the conservation and invertibility of PV, PV thinking, moist PV (MPV), and the application of PV theory.
Potential vorticity (PV) is one of the important concepts in advanced synoptic and dynamic meteorology. This paper is a brief introduction to the theory of potential vorticity, including the concept of PV, the conservation and invertibility of PV, PV thinking, moist PV (MPV), and the application of PV theory.
FU Jiaolan, MA Xuekuan, CHEN Tao, ZHANG Fang, ZHANG Xidi, SUN Jun, QUAN Wanqing, YANG Shunan, SHEN Xiaolin
2017,43(5):528-539, DOI: 10.7519/j.issn.1000-0526.2017.05.002
Abstract:
An extremely severe precipitation event took place in North China in 19-20 July 2016. It was characterized by large rainfall, persistent rainfall, warm cloud rainfall, strong local rainfall intensity and orographic precipitation. Its rainfall was larger than that of the extreme rainfall in 3-5 August 1996, and only next to the amount of the 2-7 August 1963 extreme rainfall event. It occurred under the circulation background of the South Asia high moving eastward, the West Pacific subtropical high moving northwestward and the low vortex in the westerlies developing in mid high latitude. The abnormal development of Huanghuai cyclone, southwest and southeast low level jets, and the abnormally abundant moisture indicates that the dynamic lifting and moisture conditions favored this severe rainfall process significantly. The whole rainfall event presented clearly the phase characteristics, and could be divided into two stages. The first stage was the orographic rainfall caused by the easterly winds ahead of the trough from the early morning to the daytime of 19 July, while the second part was produced by spiral rain bands in the north side of Huanghuai cyclone from the night of 19 to the daytime of 20 July. In the first stage, the easterly low level jet was lifted by the Taihang Mountains, which continuously triggered the convective cells along the east edge of the mountains. The weak dry and cold advection at mid level and the strong warm and wet advection at low level jointly maintained the convective instability. The cold pool generated by heavy rainfall and the mesoscale frontogenesis process created by local orographic effect provided favorable conditions for severe convections to occur continuously. The second stage rainfall was mainly related to the development of cut off vortex and Huanghuai cyclone. The blocking of the high pressure system slowed the steps of Huanghuai cyclone in North China, thus leading to the long lasting rainfall process.
An extremely severe precipitation event took place in North China in 19-20 July 2016. It was characterized by large rainfall, persistent rainfall, warm cloud rainfall, strong local rainfall intensity and orographic precipitation. Its rainfall was larger than that of the extreme rainfall in 3-5 August 1996, and only next to the amount of the 2-7 August 1963 extreme rainfall event. It occurred under the circulation background of the South Asia high moving eastward, the West Pacific subtropical high moving northwestward and the low vortex in the westerlies developing in mid high latitude. The abnormal development of Huanghuai cyclone, southwest and southeast low level jets, and the abnormally abundant moisture indicates that the dynamic lifting and moisture conditions favored this severe rainfall process significantly. The whole rainfall event presented clearly the phase characteristics, and could be divided into two stages. The first stage was the orographic rainfall caused by the easterly winds ahead of the trough from the early morning to the daytime of 19 July, while the second part was produced by spiral rain bands in the north side of Huanghuai cyclone from the night of 19 to the daytime of 20 July. In the first stage, the easterly low level jet was lifted by the Taihang Mountains, which continuously triggered the convective cells along the east edge of the mountains. The weak dry and cold advection at mid level and the strong warm and wet advection at low level jointly maintained the convective instability. The cold pool generated by heavy rainfall and the mesoscale frontogenesis process created by local orographic effect provided favorable conditions for severe convections to occur continuously. The second stage rainfall was mainly related to the development of cut off vortex and Huanghuai cyclone. The blocking of the high pressure system slowed the steps of Huanghuai cyclone in North China, thus leading to the long lasting rainfall process.
2012,38(10):1255-1266, DOI: 10.7519/j.issn.1000-0526.2012.10.012
Abstract:
Precipitation characteristics, environment conditions, generation and development of the mesoscale convective system that brought about the extreme torrential rain in Beijing on 21 July 2012 were analyzed comprehensively in this paper by using various conventional and unconventional data. The results showed that the extreme torrential rain had the characteristics of long duration, great rainfall and wide coverage area and its process consisted of warm area precipitation and frontal precipitation. The warm area rainfall started earlier, the severe precipitation center was scattered and lasted long while the frontal rainfallprocess contained several severe rainfall centers with high precipitation efficiency, lasting a short time.Environment conditions of the mesoscale convective system that triggered this extreme severe rainfall were analyzed. The results showed that interactions of high level divergence, the wind shear and convergence with the vortex in the lower troposphere and the surface wind convergence line provided favorable environment to the severe extreme rain. The warm humid airs from the tropical and sub tropical zones converged over the torrential rain region, continuous and sufficient water vapor manifested as high atmospheric column of precipitable water and strong low level water vapor convergence and other extreme vapor conditions for the torrential rain. In addition, the intense precipitation was triggered by the vortex wind shear, wind disturbance on low level jet, surface wind convergence line and the effect of terrain under the condition of the plentiful water vapour and maintained. With the cold front moved eastward, heavy frontal rainfall was brought by the development and evolution of convective system made by the cold air and the suitable vertical wind shear.Generation and development processes of the mesoscale convective system were also studied. The findings suggested that stratiform cloud precipitation and dispersed convective precipitation occurred firstly in the precipitation process. The warm and steady stratiform cloud precipitation changed to be highly organized convectional precipitation as the cold dry air invaded. Many small scale and mesoscale convective clusters developed into mesoscale convective complex (MCC), leading to the extreme severe precipitation. Since all the directions of the echo long axis, terrain and echo movement were parallel, train effect was obviously seen in the radar echo imegery during this precipitation process. Meanwhile, the radar echo had the characteristics of backward propagation and low centroid which was similar to tropical heavy rainfalls. Finally, a series of scientific problems were proposed according to the integrated analysis on the observation data of this rare torrential rain event, such as the causes for the extreme torrential rain and the extreme rich water vapor, mechanisms for the warm area torrential rain in the north of China, the mechanism for the train effect and backward propagation, mechanisms for the organization and maintenance of the convective cells, the simulation and analysis ability of the numerical models to extreme torrential rains and so on.
Precipitation characteristics, environment conditions, generation and development of the mesoscale convective system that brought about the extreme torrential rain in Beijing on 21 July 2012 were analyzed comprehensively in this paper by using various conventional and unconventional data. The results showed that the extreme torrential rain had the characteristics of long duration, great rainfall and wide coverage area and its process consisted of warm area precipitation and frontal precipitation. The warm area rainfall started earlier, the severe precipitation center was scattered and lasted long while the frontal rainfallprocess contained several severe rainfall centers with high precipitation efficiency, lasting a short time.Environment conditions of the mesoscale convective system that triggered this extreme severe rainfall were analyzed. The results showed that interactions of high level divergence, the wind shear and convergence with the vortex in the lower troposphere and the surface wind convergence line provided favorable environment to the severe extreme rain. The warm humid airs from the tropical and sub tropical zones converged over the torrential rain region, continuous and sufficient water vapor manifested as high atmospheric column of precipitable water and strong low level water vapor convergence and other extreme vapor conditions for the torrential rain. In addition, the intense precipitation was triggered by the vortex wind shear, wind disturbance on low level jet, surface wind convergence line and the effect of terrain under the condition of the plentiful water vapour and maintained. With the cold front moved eastward, heavy frontal rainfall was brought by the development and evolution of convective system made by the cold air and the suitable vertical wind shear.Generation and development processes of the mesoscale convective system were also studied. The findings suggested that stratiform cloud precipitation and dispersed convective precipitation occurred firstly in the precipitation process. The warm and steady stratiform cloud precipitation changed to be highly organized convectional precipitation as the cold dry air invaded. Many small scale and mesoscale convective clusters developed into mesoscale convective complex (MCC), leading to the extreme severe precipitation. Since all the directions of the echo long axis, terrain and echo movement were parallel, train effect was obviously seen in the radar echo imegery during this precipitation process. Meanwhile, the radar echo had the characteristics of backward propagation and low centroid which was similar to tropical heavy rainfalls. Finally, a series of scientific problems were proposed according to the integrated analysis on the observation data of this rare torrential rain event, such as the causes for the extreme torrential rain and the extreme rich water vapor, mechanisms for the warm area torrential rain in the north of China, the mechanism for the train effect and backward propagation, mechanisms for the organization and maintenance of the convective cells, the simulation and analysis ability of the numerical models to extreme torrential rains and so on.
2006,32(10):64-69, DOI: 10.7519/j.issn.1000-0526.2006.10.010
Abstract:
Based on the data of CINRAD Doppler Radar which located at Xinle of Hebei Province,the hail,strong wind and heavy rainfall weather events in mid-south Hebei in 2004 are statistically analyzed.The routine radar products,such as echo reflectivity,radial velocity,Vertically Integrated Liquid(VIL)Water,hail index,mesocyclone,velocity azimuth display wind profile,etc.are used in this statistics.The results show that hail's VIL value is larger than generic thunder storm's.At the same time,greater VIL value and longer sustaining will bring about greater diameter hail and larger effect area.It is the very useful index to indicate strong wind in mesocyclone products and the wind direction sudden change in radial velocity products.A reference based on analyzing this type synoptic forecast with radar system in future is proposed.
Based on the data of CINRAD Doppler Radar which located at Xinle of Hebei Province,the hail,strong wind and heavy rainfall weather events in mid-south Hebei in 2004 are statistically analyzed.The routine radar products,such as echo reflectivity,radial velocity,Vertically Integrated Liquid(VIL)Water,hail index,mesocyclone,velocity azimuth display wind profile,etc.are used in this statistics.The results show that hail's VIL value is larger than generic thunder storm's.At the same time,greater VIL value and longer sustaining will bring about greater diameter hail and larger effect area.It is the very useful index to indicate strong wind in mesocyclone products and the wind direction sudden change in radial velocity products.A reference based on analyzing this type synoptic forecast with radar system in future is proposed.
Zhou Yuquan, Chen Yingying, Li Juan, Huang Yimei, He Xiaodong, Zhou Feifei, Wu Menxin, Hu Bo, Mao Jietai
2008,34(12):27-35, DOI: 10.7519/j.issn.1000-0526.2008.12.004
Abstract:
Cloud macro and micro physical characteristic parameters play an important role not only in the field of the analysis and forecast of the weather and climate, but also in the field of weather modification to identify the seeding c ondition. Based on the data from FY-2C/D stationary satellite and SBDART radiati on transfer model, associated with the sounding data and surface information, a method retrieving cloud macro and micro physical parameters is established in th is research. These parameters include cloud top height, cloud top temperature, d epth of super-cooled layer, depth of warm layer, cloud bottom height, depth of c loud, cloud optical thickness, cloud effective particle radius and cloud liquid water content. It has been run operationally. In this paper, the correlated info rmation such as physical meaning, retrieving method and technology, retrieving p rocess and data format are simply introduced. Furthermore, comparing with the ob servation of Cloudsat up to the minute, the retrieving results of main cloud par ameters are proved to be reasonable and usable. By contrast with same kind produ cts of MODIS, it also shows good corresponding relationship.
Cloud macro and micro physical characteristic parameters play an important role not only in the field of the analysis and forecast of the weather and climate, but also in the field of weather modification to identify the seeding c ondition. Based on the data from FY-2C/D stationary satellite and SBDART radiati on transfer model, associated with the sounding data and surface information, a method retrieving cloud macro and micro physical parameters is established in th is research. These parameters include cloud top height, cloud top temperature, d epth of super-cooled layer, depth of warm layer, cloud bottom height, depth of c loud, cloud optical thickness, cloud effective particle radius and cloud liquid water content. It has been run operationally. In this paper, the correlated info rmation such as physical meaning, retrieving method and technology, retrieving p rocess and data format are simply introduced. Furthermore, comparing with the ob servation of Cloudsat up to the minute, the retrieving results of main cloud par ameters are proved to be reasonable and usable. By contrast with same kind produ cts of MODIS, it also shows good corresponding relationship.
ZHANG Xiaoling, ZHANG Tao, LIU Xinhua, ZHOU Qingliang, CHEN Yun, ZHOU Xiaoxia, ZHENG Yongguang, ZHAO Surong
2010,36(7):143-150, DOI: 10.7519/j.issn.1000-0526.2010.7.021
Abstract:
Mesoscale severe weather forecasting ability is limited, in some sense for a lack of valid analysis on mesoscale convective systems and its favorable environments. This paper introduces the mesoscale weather chart analysis techniq ue which was tested in the National Meteorological Center (NMC). Mesoscale weath er chart analyzes the favorable environmental conditions of mesoscale convective systems based on observational data and numerical weather forecast outputs. It includes upper air composite chart and surface chart. In the upper air composite ch art, by analyzing wind, temperature, moisture, temperature change and height change, the diagnostic systems and features in all the lower, middle and upper t roposphere isobaric layers are combined into one plot, which can clearly displa y the available environments and synoptic pattern of severe convective weather. In the surface chart, the analysis contents are pressure, wind, temperature, moi sture, convective weather phenomena and all kinds of boundaries (fronts). The te st in NMC shows that mesoscale weather chart analysis is a dependable means for severe convective weather outlook forecasting.
Mesoscale severe weather forecasting ability is limited, in some sense for a lack of valid analysis on mesoscale convective systems and its favorable environments. This paper introduces the mesoscale weather chart analysis techniq ue which was tested in the National Meteorological Center (NMC). Mesoscale weath er chart analyzes the favorable environmental conditions of mesoscale convective systems based on observational data and numerical weather forecast outputs. It includes upper air composite chart and surface chart. In the upper air composite ch art, by analyzing wind, temperature, moisture, temperature change and height change, the diagnostic systems and features in all the lower, middle and upper t roposphere isobaric layers are combined into one plot, which can clearly displa y the available environments and synoptic pattern of severe convective weather. In the surface chart, the analysis contents are pressure, wind, temperature, moi sture, convective weather phenomena and all kinds of boundaries (fronts). The te st in NMC shows that mesoscale weather chart analysis is a dependable means for severe convective weather outlook forecasting.
2013,39(10):1284-1292, DOI: 10.7519/j.issn.1000-0526.2013.10.006
Abstract:
Based on the fog observation data during 24-27 December 2006 (advection radiation fog), NCEP NC reanalysis data (2.5°×2.5°) and GDAS global meteorological data (1°×1°), detailed trajectory analysis of the boundary layer characteristics and water vapor transport of the fog is investigated, combined with the weather condition, meteorological elements and physical quantity field. The results show that: (1) there is thick inversion layer, even multi layer inversion throughout the dense fog event. Temperatures of different inversion tops in the middle and high levels are 2-5℃ higher than the surface temperature. The thickness of inversion layer is more than 200 m, and it gets to 500 m at 08:00 BT 26 December, indicating the atmosphere is very stable and conducive to the convergence of water vapor before the fog forms. However, it is not favorable for the divergence of water vapor after the formation of fog, which helps the development and maintenance of the fog, causing the fog to last about 64 hours with dense fog (visibility <50 m) about 37 hours; (2) The divergence of water vapor flux in low level is negative in the advection fog event. The upper air has persistent moisture convergence and the strongest moisture convergence appears at 02:00 BT 25 December, being -30×10-7 g·s-1·cm-2·hPa-1. The accumulation of low level water vapor makes fog form and develop while the divergence of water vapor flux speeds up its dissipation. 〖JP2〗The long lasting advection radiation fog is mainly caused by the continuous water vapor convergence; (3) The water vapor path is from the coastal area in easten China to Nanjing. The water vapor is continuously supplied from sea during the fog event, with the water vapor flux maximum getting to 2 g·s-1·hPa-1·cm-1. The sufficient supply and supplementary of water vapor determines the duration of the fog.
Based on the fog observation data during 24-27 December 2006 (advection radiation fog), NCEP NC reanalysis data (2.5°×2.5°) and GDAS global meteorological data (1°×1°), detailed trajectory analysis of the boundary layer characteristics and water vapor transport of the fog is investigated, combined with the weather condition, meteorological elements and physical quantity field. The results show that: (1) there is thick inversion layer, even multi layer inversion throughout the dense fog event. Temperatures of different inversion tops in the middle and high levels are 2-5℃ higher than the surface temperature. The thickness of inversion layer is more than 200 m, and it gets to 500 m at 08:00 BT 26 December, indicating the atmosphere is very stable and conducive to the convergence of water vapor before the fog forms. However, it is not favorable for the divergence of water vapor after the formation of fog, which helps the development and maintenance of the fog, causing the fog to last about 64 hours with dense fog (visibility <50 m) about 37 hours; (2) The divergence of water vapor flux in low level is negative in the advection fog event. The upper air has persistent moisture convergence and the strongest moisture convergence appears at 02:00 BT 25 December, being -30×10-7 g·s-1·cm-2·hPa-1. The accumulation of low level water vapor makes fog form and develop while the divergence of water vapor flux speeds up its dissipation. 〖JP2〗The long lasting advection radiation fog is mainly caused by the continuous water vapor convergence; (3) The water vapor path is from the coastal area in easten China to Nanjing. The water vapor is continuously supplied from sea during the fog event, with the water vapor flux maximum getting to 2 g·s-1·hPa-1·cm-1. The sufficient supply and supplementary of water vapor determines the duration of the fog.
2014,40(4):400-411, DOI: 10.7519/j.issn.1000-0526.2014.04.002
Abstract:
Based on the synoptic environment analysis of about 100 severe convection cases in China since 2000 and the reference of related literatures, from the perspectives of the three essential conditions for the development of severe convection, namely the thermal instability, lift and moisture, five basic synoptic situation configurations of severe convection in China are proposed and expounded. They are cold advection forcing category, warm advection forcing category, baroclinic frontogenesis category, quasi barotropic category and elevated thunderstorm category. The typical characteristics of the upper cold advection forcing category is that the mid upper strong cold advection above 500 hPa strengthens and reaches the boundary warm convergence zone. The warm advection forcing category is characterized by trough with special structure moving over low level strong warm and moist advection. The deep convection produced by the mid lower layer convergence of cold and warm air features the baroclinic frontogenesis category. The quasi barotropic category mostly occurs at the northern and the southern edges or the interior of summer subtropical high and the area with weak baroclinicity, where the dynamic forcing and the surface inhomogeneous local heating play major roles. The features of elevated thunderstorms are the southwest jet in 700-500 hPa lifted by boundary cold wedge and the instable energy is from above 700 hPa. The classification based on the difference of the formation mechanisms can grasp accurately the synoptic characteristics, the situation configurations, the dynamic and thermal properties and the key points in analyzing short term potential forecast, providing more technical support to further enhance the level of weather prediction.
Based on the synoptic environment analysis of about 100 severe convection cases in China since 2000 and the reference of related literatures, from the perspectives of the three essential conditions for the development of severe convection, namely the thermal instability, lift and moisture, five basic synoptic situation configurations of severe convection in China are proposed and expounded. They are cold advection forcing category, warm advection forcing category, baroclinic frontogenesis category, quasi barotropic category and elevated thunderstorm category. The typical characteristics of the upper cold advection forcing category is that the mid upper strong cold advection above 500 hPa strengthens and reaches the boundary warm convergence zone. The warm advection forcing category is characterized by trough with special structure moving over low level strong warm and moist advection. The deep convection produced by the mid lower layer convergence of cold and warm air features the baroclinic frontogenesis category. The quasi barotropic category mostly occurs at the northern and the southern edges or the interior of summer subtropical high and the area with weak baroclinicity, where the dynamic forcing and the surface inhomogeneous local heating play major roles. The features of elevated thunderstorms are the southwest jet in 700-500 hPa lifted by boundary cold wedge and the instable energy is from above 700 hPa. The classification based on the difference of the formation mechanisms can grasp accurately the synoptic characteristics, the situation configurations, the dynamic and thermal properties and the key points in analyzing short term potential forecast, providing more technical support to further enhance the level of weather prediction.
2015,41(2):212-218, DOI: 10.7519/j.issn.1000-0526.2015.02.009
Abstract:
From 1 May to 8 June 2013 CMA Meteorological Observation Centre conducted an experiment of cloud height observations by using cloud radar (35 GHz), whose observation data are the echo power value and temporal resolution is 1 min and a ceilometer whose observation data are the back scattering intens data with 1 min temporal resolution. The result of analyzing the data observed from the 39 d experiment indicates that: (1) the data acquisition ratio of cloud radar is 26% larger than that of ceilometer; (2) the ratio is 51% in fog haze weather; (3) relatively, precipitation has more significant effect on cloud base height measured by laser ceilometer than that by cloud radar; (4) height of cloud base measured by cloud radar is almost consistent with the height by ceilometer because their average deviation is less than 300 m.
From 1 May to 8 June 2013 CMA Meteorological Observation Centre conducted an experiment of cloud height observations by using cloud radar (35 GHz), whose observation data are the echo power value and temporal resolution is 1 min and a ceilometer whose observation data are the back scattering intens data with 1 min temporal resolution. The result of analyzing the data observed from the 39 d experiment indicates that: (1) the data acquisition ratio of cloud radar is 26% larger than that of ceilometer; (2) the ratio is 51% in fog haze weather; (3) relatively, precipitation has more significant effect on cloud base height measured by laser ceilometer than that by cloud radar; (4) height of cloud base measured by cloud radar is almost consistent with the height by ceilometer because their average deviation is less than 300 m.
2012,38(2):164-173, DOI: 10.7519/j.issn.1000-0526.2012.02.004
Abstract:
Many weather forecasters seem to have acquaintance with most of basic concepts or fundamental theories which are connected with severe convection, but some of them are misapplied frequently by some forecasters when they are engaged in severe convective weather analysis or forecasting argumentation. Due to the above problem, some basic concepts and fundamental theories should be explained from the view of forecasting application. The following issues are discussed in this paper. They are the relationship between humidity and water vapor content, the role of clod air during the precipitation process, the fundamental theories connected with thermal and dynamic instability, the sounding analysis related to instability parameters, the relationship between helicity or moist potential vorticity and instability, the relationship among the convergence line, lifting velocity and convective vertical movement, and the essential connection between the synoptic patterns and severe convective phenomena.
Many weather forecasters seem to have acquaintance with most of basic concepts or fundamental theories which are connected with severe convection, but some of them are misapplied frequently by some forecasters when they are engaged in severe convective weather analysis or forecasting argumentation. Due to the above problem, some basic concepts and fundamental theories should be explained from the view of forecasting application. The following issues are discussed in this paper. They are the relationship between humidity and water vapor content, the role of clod air during the precipitation process, the fundamental theories connected with thermal and dynamic instability, the sounding analysis related to instability parameters, the relationship between helicity or moist potential vorticity and instability, the relationship among the convergence line, lifting velocity and convective vertical movement, and the essential connection between the synoptic patterns and severe convective phenomena.
2009,35(1):55-64, DOI: 10.7519/j.issn.1000-0526.2009.1.007
Abstract:
A strong rainstorm is analysis which occurred in Xinghua located the north of Ji angsu province on 25 July 2007. Results show that wind disaster originated from two kinds of rainstorm. One kind was the gust front which occurred at the front of the storm. Strong wind of grade 7-9 was attained when it happened. Another ki nd was the downburst arose in the multi cell storm. The original height of refl ectivity core was higher than -20℃ isotherm. It had the characteristics of conv ergence on the mid level and descending of reflectivity core. The strong wind ab ove grade 10 was attained, when the descending airflow diverged strongly on the ground. A new cell was combined with the former storm above the gust front, thus the storm enhanced. When the downburst happened, the storm weakened, and another new cell was combin ed with the former storm. The downburst happened continuously, and the impact of gust front persisted.
A strong rainstorm is analysis which occurred in Xinghua located the north of Ji angsu province on 25 July 2007. Results show that wind disaster originated from two kinds of rainstorm. One kind was the gust front which occurred at the front of the storm. Strong wind of grade 7-9 was attained when it happened. Another ki nd was the downburst arose in the multi cell storm. The original height of refl ectivity core was higher than -20℃ isotherm. It had the characteristics of conv ergence on the mid level and descending of reflectivity core. The strong wind ab ove grade 10 was attained, when the descending airflow diverged strongly on the ground. A new cell was combined with the former storm above the gust front, thus the storm enhanced. When the downburst happened, the storm weakened, and another new cell was combin ed with the former storm. The downburst happened continuously, and the impact of gust front persisted.
2014,40(2):133-145, DOI: 10.7519/j.issn.1000-0526.2014.02.001
Abstract:
By using the NCEP reanalysis data, the vapor budget of the area covered by the severe torrential rain over the northeast of North China on 21 July, 2012 is calculated according to the vapor budget equation. The results show that meridional water vapor transportation is dominant while the extremely heavy rain hits Beijing Region, where most moist vapor comes from the southern boundary below 500 hPa. The low level regional moisture convergence is consistent with the time and space when the torrential rain breaks out and develops. Above the middle level the vertical vapor transport is more prominent. Then the variation features of the vapor transport corridors and their moisture contributions are got through the HYSPLIT mode. The backward trajectory analyses illustrate two major vapor transport corridors. The moistest vapor derived from Yellow Sea and East China Sea along the low level make the main moisture contribution during the heavy precipitation. Moisture from the South China Sea and the Bay of Bengal strengthens the water vapor in the region when the heavy rain starts and develops. Also the drier vapor corridor along the high level from the northwest of China plays an important role in this case.
By using the NCEP reanalysis data, the vapor budget of the area covered by the severe torrential rain over the northeast of North China on 21 July, 2012 is calculated according to the vapor budget equation. The results show that meridional water vapor transportation is dominant while the extremely heavy rain hits Beijing Region, where most moist vapor comes from the southern boundary below 500 hPa. The low level regional moisture convergence is consistent with the time and space when the torrential rain breaks out and develops. Above the middle level the vertical vapor transport is more prominent. Then the variation features of the vapor transport corridors and their moisture contributions are got through the HYSPLIT mode. The backward trajectory analyses illustrate two major vapor transport corridors. The moistest vapor derived from Yellow Sea and East China Sea along the low level make the main moisture contribution during the heavy precipitation. Moisture from the South China Sea and the Bay of Bengal strengthens the water vapor in the region when the heavy rain starts and develops. Also the drier vapor corridor along the high level from the northwest of China plays an important role in this case.
2014,40(4):389-399, DOI: 10.7519/j.issn.1000-0526.2014.04.001
Abstract:
Thunderstorm potential forecasting based on three ingredients has been widely accepted. This article aims to discuss some basical questions in operational forecast applications, and clarify some easily confused concepts. The content includes atmospheric instablility and convection, thunderstorms trigger mechanism and lifting and its relationship with snoptical weather system, how to deal with the three elements of the thunderstorm “enough”, the combination of pattern recognition and ingredients based forecasting methodology. Atmospheric instablility is one of the three ingredients of convection initiation, and it is also very important to thunderstorm short time forecasting and analysis. This paper discusses various mesoscale instability related to the thunderstorm, and inicates how to estimate the spatial and temporal evolution of CAPE. In addition, the definition and criterion for potential instability and symmetric instability are discussed profoundly.
Thunderstorm potential forecasting based on three ingredients has been widely accepted. This article aims to discuss some basical questions in operational forecast applications, and clarify some easily confused concepts. The content includes atmospheric instablility and convection, thunderstorms trigger mechanism and lifting and its relationship with snoptical weather system, how to deal with the three elements of the thunderstorm “enough”, the combination of pattern recognition and ingredients based forecasting methodology. Atmospheric instablility is one of the three ingredients of convection initiation, and it is also very important to thunderstorm short time forecasting and analysis. This paper discusses various mesoscale instability related to the thunderstorm, and inicates how to estimate the spatial and temporal evolution of CAPE. In addition, the definition and criterion for potential instability and symmetric instability are discussed profoundly.
2012,38(1):1-16, DOI: 10.7519/j.issn.1000-0526.2012.01.001
Abstract:
In this paper, the modulation of atmospheric MJO on typhoon generation over the northwestern Pacific and its mechanism are first studied by using the MJO index. The results show that the MJO plays an important modulation role in typhoon generation over the northwestern Pacific: The proportion of typhoon number is 21 between active period and inactive period; During the MJO active period, the proportion of typhoon number is also 2:1 between phases 5-6 and phases 2-3 of MJO. The composite analyses of atmospheric circulation show that there are different circulation patterns over the northwestern Pacific in different phases of the MJO, which will affect the typhoon generation. In phases 5-6 (2-3), the dynamic factor and convective heating patterns over western Pacific are favorable (unfavorable) for typhoon generation. Then， the comparing analyses of the 30-60 day low frequency kinetic energy in lower and higher levels of the troposphere show that the atmospheric intraseasonal oscillation over the northwestern Pacific has a clear impact on the typhoon generation. There is an evident positive (negative) anomaly area of 30-60 day low frequency kinetic energy in the more (less) typhoon years over the northwestern Pacific east of the Philippines, which means that strong (weak) atmospheric intraseasonal oscillation (ISO) over the northwestern Pacific is favorable (unfavorable) for typhoon generation. The analyses of 200 hPa velocity potential show that there is a clear divergence (convergence) pattern over the northwestern Pacific in the more (less) typhoon years, which is favorable (unfavorable) for typhoon generation. The modulation of the intraseasonal oscillation on the typhoon tracks over the northwestern Pacific is studied by observational data analyses. We classified the main classes of typhoon tracks into 5 types as straight west moving typhoons (I), northwest moving typhoons (II), recurving to Korea/west of Japan typhoons (III), landing on Japan typhoons (IV) and recurving to the east of Japan typhoons (V). Then the composite analyses of atmospheric low-frequency wind fields at 850, 500 and 200 hPa, corresponding to the typhoon forming date, for every typhoon track are completed. The analysis results of relationships between the low-frequency (ISO) wind fields and typhoon tracks have indicated that the typhoon tracks will be affected by wind pattern of the ISO. The low frequency positive vorticity belt (the maximum value line of cyclonic vorticity) associated with low-frequency cyclone (LFC) at 850 hPa is so closely related to the typhoon track, that the maximum value line (belt) of low frequency cyclonic vorticity can be an important factor to predicate the typhoon tracks over the northwestern Pacific. And the typhoon tracks will be also affected by the ISO circulation pattern at 200 hPa, particularly the strong low frequency wind associated with low frequency anticyclone (LFAC).
In this paper, the modulation of atmospheric MJO on typhoon generation over the northwestern Pacific and its mechanism are first studied by using the MJO index. The results show that the MJO plays an important modulation role in typhoon generation over the northwestern Pacific: The proportion of typhoon number is 21 between active period and inactive period; During the MJO active period, the proportion of typhoon number is also 2:1 between phases 5-6 and phases 2-3 of MJO. The composite analyses of atmospheric circulation show that there are different circulation patterns over the northwestern Pacific in different phases of the MJO, which will affect the typhoon generation. In phases 5-6 (2-3), the dynamic factor and convective heating patterns over western Pacific are favorable (unfavorable) for typhoon generation. Then， the comparing analyses of the 30-60 day low frequency kinetic energy in lower and higher levels of the troposphere show that the atmospheric intraseasonal oscillation over the northwestern Pacific has a clear impact on the typhoon generation. There is an evident positive (negative) anomaly area of 30-60 day low frequency kinetic energy in the more (less) typhoon years over the northwestern Pacific east of the Philippines, which means that strong (weak) atmospheric intraseasonal oscillation (ISO) over the northwestern Pacific is favorable (unfavorable) for typhoon generation. The analyses of 200 hPa velocity potential show that there is a clear divergence (convergence) pattern over the northwestern Pacific in the more (less) typhoon years, which is favorable (unfavorable) for typhoon generation. The modulation of the intraseasonal oscillation on the typhoon tracks over the northwestern Pacific is studied by observational data analyses. We classified the main classes of typhoon tracks into 5 types as straight west moving typhoons (I), northwest moving typhoons (II), recurving to Korea/west of Japan typhoons (III), landing on Japan typhoons (IV) and recurving to the east of Japan typhoons (V). Then the composite analyses of atmospheric low-frequency wind fields at 850, 500 and 200 hPa, corresponding to the typhoon forming date, for every typhoon track are completed. The analysis results of relationships between the low-frequency (ISO) wind fields and typhoon tracks have indicated that the typhoon tracks will be affected by wind pattern of the ISO. The low frequency positive vorticity belt (the maximum value line of cyclonic vorticity) associated with low-frequency cyclone (LFC) at 850 hPa is so closely related to the typhoon track, that the maximum value line (belt) of low frequency cyclonic vorticity can be an important factor to predicate the typhoon tracks over the northwestern Pacific. And the typhoon tracks will be also affected by the ISO circulation pattern at 200 hPa, particularly the strong low frequency wind associated with low frequency anticyclone (LFAC).
2014,40(7):816-826, DOI: 10.7519/j.issn.1000-0526.2014.07.005
Abstract:
In term of precipitation data of 2400 stations from 1981 to 2010, annual, seasonal and monthly distribution and evolution characteristics of rainstorm were analyzed. The results show that the processes of rainstorm have been increased evidently since 21 century especially in the south of China, but the duration is relatively short. Rainstorm days have been increased, but the amount of precipitation is not as much as in 1990s. Variation trend of the annual (monthly) precipitation amount is in accordance with that of rainstorm days, but rainfall is averagely more while the rainstorm days are less during spring rainfall phase over the south of Yangtze River. Distribution of the maximum annual rainstorm days is very similar with that of the annual mean rainstorm days, revealing the feature of more in south and east but less in north and west. Maximum annual rainstorm days are more than double of annual average rainstorm days with multi centers due to the effect of topography. The months of maximum monthly rainstorm days over different regions of the same province are incompletely same as the result of the impact of different weather systems. Generally, rainstorm days have been increased since 2000, rainstorm begins earlier, ends latter and lasts longer than before. Nowadays, as the extreme rainfall events and secondary disasters happen frequently, it is conducive for the forecast of quantitative precipitation forecast (QPF) to learn the spatio temporal distribution and evolution features of rainstorm.
In term of precipitation data of 2400 stations from 1981 to 2010, annual, seasonal and monthly distribution and evolution characteristics of rainstorm were analyzed. The results show that the processes of rainstorm have been increased evidently since 21 century especially in the south of China, but the duration is relatively short. Rainstorm days have been increased, but the amount of precipitation is not as much as in 1990s. Variation trend of the annual (monthly) precipitation amount is in accordance with that of rainstorm days, but rainfall is averagely more while the rainstorm days are less during spring rainfall phase over the south of Yangtze River. Distribution of the maximum annual rainstorm days is very similar with that of the annual mean rainstorm days, revealing the feature of more in south and east but less in north and west. Maximum annual rainstorm days are more than double of annual average rainstorm days with multi centers due to the effect of topography. The months of maximum monthly rainstorm days over different regions of the same province are incompletely same as the result of the impact of different weather systems. Generally, rainstorm days have been increased since 2000, rainstorm begins earlier, ends latter and lasts longer than before. Nowadays, as the extreme rainfall events and secondary disasters happen frequently, it is conducive for the forecast of quantitative precipitation forecast (QPF) to learn the spatio temporal distribution and evolution features of rainstorm.
2011,37(10):1262-1269, DOI: 10.7519/j.issn.1000-0526.2011.10.009
Abstract:
Based on the daily precipitation data at 110 observational stations during 1961-2008 in South China， the climatic characteristics and variation of torrential rain days， rainstorm intensity and contribution which is in annual， the first and second flood seasons in South China were studied by using statistical and diagnostic methods， such as linear regression analysis， Mann Kendall test， wavelet analysis and the computation of trend coefficients. The results have shown that the annual mean torrential rain days have a decreasing trend from coastal regions to inland in South China in recent 48 years， the highest center is in Dongxing of Guangxi （14.9 d）， and the lowest center is in Longlin of Guangxi （3.2 d）. About 72% of the total torrential rain days occurred in the flood seasons with about 45% in the first season and 27% in the second season. The mean torrential rain days have increased faintly in annual， the first and second flood seasons in South China， but it is not obvious. There are the characteristics of interannual and interdecadal changes. The mean rainstorm intensity has increased faintly in annual and in the first flood season in South China. However, since 2005 it has become obviously. The mean rainstorm intensity has declined in the second flood season， but it is not obvious. The annual mean rainstorm contribution to the total rainfall has increased obviously， but the mean contribution is not obvious in the first and second flood seasons. The wavelet analysis has shown that the changes of torrential rain days， intensity and contribution which is in annual， the first and second flood seasons in South China have two significant periods of 2-3 a and 3-4 a.
Based on the daily precipitation data at 110 observational stations during 1961-2008 in South China， the climatic characteristics and variation of torrential rain days， rainstorm intensity and contribution which is in annual， the first and second flood seasons in South China were studied by using statistical and diagnostic methods， such as linear regression analysis， Mann Kendall test， wavelet analysis and the computation of trend coefficients. The results have shown that the annual mean torrential rain days have a decreasing trend from coastal regions to inland in South China in recent 48 years， the highest center is in Dongxing of Guangxi （14.9 d）， and the lowest center is in Longlin of Guangxi （3.2 d）. About 72% of the total torrential rain days occurred in the flood seasons with about 45% in the first season and 27% in the second season. The mean torrential rain days have increased faintly in annual， the first and second flood seasons in South China， but it is not obvious. There are the characteristics of interannual and interdecadal changes. The mean rainstorm intensity has increased faintly in annual and in the first flood season in South China. However, since 2005 it has become obviously. The mean rainstorm intensity has declined in the second flood season， but it is not obvious. The annual mean rainstorm contribution to the total rainfall has increased obviously， but the mean contribution is not obvious in the first and second flood seasons. The wavelet analysis has shown that the changes of torrential rain days， intensity and contribution which is in annual， the first and second flood seasons in South China have two significant periods of 2-3 a and 3-4 a.
2014,40(11):1372-1379, DOI: 10.7519/j.issn.1000-0526.2014.11.010
Abstract:
The hourly precipitation observation data from 2447 rain gauge records are used to verify and evaluate the satellite precipitation estimation products of Climate Prediction Center Morphing Technique (CMORPH) and Tropical Rainfall Measuring Mission (TRMM) 3B42 during 2007-2010 in China. The results show that the two satellite precipitation data are similar to ground gain gauge data in revealing the spatial patterns of daily mean precipitation amount. The pattern correlation coefficients of 3 h rainfall amount are over 0.5 and 0.4 in most areas, respectively. Bias of two satellite precipitation products are both between the positive and negative 0.25 mm, but there are significant difference between the north and the south. And the mean absolute error, relative error and root mean square error all have a significant seasonal periodic variations. The two satellite precipitation products can reflect the summer rainfall diurnal variation well in most parts of China, but there are also clear distinctions in some areas. The overall vacancy retrieval rate of CMORPH and TRMM 3B42 products are 7.23% and 2.63%, overall missing retrieval rate are 3.25% and 5.5%, respectively.
The hourly precipitation observation data from 2447 rain gauge records are used to verify and evaluate the satellite precipitation estimation products of Climate Prediction Center Morphing Technique (CMORPH) and Tropical Rainfall Measuring Mission (TRMM) 3B42 during 2007-2010 in China. The results show that the two satellite precipitation data are similar to ground gain gauge data in revealing the spatial patterns of daily mean precipitation amount. The pattern correlation coefficients of 3 h rainfall amount are over 0.5 and 0.4 in most areas, respectively. Bias of two satellite precipitation products are both between the positive and negative 0.25 mm, but there are significant difference between the north and the south. And the mean absolute error, relative error and root mean square error all have a significant seasonal periodic variations. The two satellite precipitation products can reflect the summer rainfall diurnal variation well in most parts of China, but there are also clear distinctions in some areas. The overall vacancy retrieval rate of CMORPH and TRMM 3B42 products are 7.23% and 2.63%, overall missing retrieval rate are 3.25% and 5.5%, respectively.
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