ISSN 1000-0526
CN 11-2282/P
CN 11-2282/P
Volume 51,Issue 10,2025 Table of Contents
2025, 51(10):1157-1170.
DOI: 10.7519/j.issn.1000-0526.2025.063002
Abstract:
This paper comprehensively uses multi-source high-frequency detection data to analyze the formation causes and development of a localized severe convective event that occurred in Beijing on 27 August 2020, and the applicability of the observation data in nowcasting and warning of such severe convection. Utilizing the data from various high-frequency detection instruments including microwave radiometers, wind profile radars, S-band Doppler radars, X-band dual-polarization radars, and a three-dimensional lightning positioning system, we investigate the evolutionary characteristics and warning indicators during thunderstorm initiation, development and dissipation stages. The results demonstrate that the microwave radiometer-retrieved temperature, humidity and stability parameters (K-index, SI-index) show significant variations 30-120 min prior to the outbreak of severe convection, effectively indicating the energy accumulation. The enhanced vertical wind shear and low-level warm advection detected by wind profile radars can reflect dynamic lifting condition 55-120 min in advance. S/X-band radar observations of echo overhanging structures, centroid height variations, and dual-polarization parameters (ZDR, KDP) enable the identification of hail growth zones, achieving 12-37 min lead time for hail and thunderstorm gale warnings. Lightning jump signals (2σ algorithm) exhibit strong correlation with severe weather (hail and winds), with the first jump providing 52 min lead time for hail warning. Validation of other four severe convective cases in 2020 shows that synergistic application of multi-source observations can overcome the limitation of single-instrument detection, enabling dynamic tracking of environmental energy, storm structure and lightning activities, thereby providing valuable references for short-time forecasting and nowcasting.
This paper comprehensively uses multi-source high-frequency detection data to analyze the formation causes and development of a localized severe convective event that occurred in Beijing on 27 August 2020, and the applicability of the observation data in nowcasting and warning of such severe convection. Utilizing the data from various high-frequency detection instruments including microwave radiometers, wind profile radars, S-band Doppler radars, X-band dual-polarization radars, and a three-dimensional lightning positioning system, we investigate the evolutionary characteristics and warning indicators during thunderstorm initiation, development and dissipation stages. The results demonstrate that the microwave radiometer-retrieved temperature, humidity and stability parameters (K-index, SI-index) show significant variations 30-120 min prior to the outbreak of severe convection, effectively indicating the energy accumulation. The enhanced vertical wind shear and low-level warm advection detected by wind profile radars can reflect dynamic lifting condition 55-120 min in advance. S/X-band radar observations of echo overhanging structures, centroid height variations, and dual-polarization parameters (ZDR, KDP) enable the identification of hail growth zones, achieving 12-37 min lead time for hail and thunderstorm gale warnings. Lightning jump signals (2σ algorithm) exhibit strong correlation with severe weather (hail and winds), with the first jump providing 52 min lead time for hail warning. Validation of other four severe convective cases in 2020 shows that synergistic application of multi-source observations can overcome the limitation of single-instrument detection, enabling dynamic tracking of environmental energy, storm structure and lightning activities, thereby providing valuable references for short-time forecasting and nowcasting.
2025, 51(10):1171-1181.
DOI: 10.7519/j.issn.1000-0526.2025.011603
Abstract:
On the afternoon of 13 August 2022, a local severe convection occurred near the coast of Shanghai under the control of Western Pacific subtropical high. This event displayed characteristics of a short life span, strong local manifestation, and high intensity. Using the data from minute-level surface automatic weather stations, FY-4A geostationary meteorological satellite cloud images, and dual-polarization radar data, this paper studies the nowcasting focus and causes of this local severe convection. The findings are as follows. The beginning of precipitation at the surface was identified as the accurrence sign of local severe convective events. By analyzing radar reflectivity factor, satellite visible light cloud images, and Q vector divergence, combined with perturbation dew point temperature and perturbation temperature data from surface automatic weather stations, we find the early warning of the convective event could be issued 23, 70 and 100 min in advance, respectively. This integrated monitoring and mutual verification of the atmospheric, satellite, and sruface observations not only improved the lead time of early warning for local severe convection, but also reduced missed detections. Under the control of the Western Pacific subtropical high, temperatures exceeding 35℃, combined with the perturbations in temperature and dew point temperature near the urban area, provided favorable thermodynamic conditions for the initiation of deep convection. Simultaneously, differences in land-water underlying characteristics led to higher temperatures on urban land compared to the temperature of adjacent Yangtze River water, thus, onshore winds were formed. On one hand, this process experienced abrupt changes in land-water underlying characteristics and complex urban land surfaces, causing convergence of wind direction and speed. On the other hand, the convergence of warm and cold air caused the enhanced instability of atmosphere. Further analysis reveals that the convergence of significant Q vector divergence at the surface persisted until surface precipitation occurred, indicating the generation of vertical upward motion due to the dynamic and thermodynamic forcings at the surface. Furthermore, the interaction between the sea breeze front and the convergence-induced updrafts from the urban heat island resulted in the local severe convection.
On the afternoon of 13 August 2022, a local severe convection occurred near the coast of Shanghai under the control of Western Pacific subtropical high. This event displayed characteristics of a short life span, strong local manifestation, and high intensity. Using the data from minute-level surface automatic weather stations, FY-4A geostationary meteorological satellite cloud images, and dual-polarization radar data, this paper studies the nowcasting focus and causes of this local severe convection. The findings are as follows. The beginning of precipitation at the surface was identified as the accurrence sign of local severe convective events. By analyzing radar reflectivity factor, satellite visible light cloud images, and Q vector divergence, combined with perturbation dew point temperature and perturbation temperature data from surface automatic weather stations, we find the early warning of the convective event could be issued 23, 70 and 100 min in advance, respectively. This integrated monitoring and mutual verification of the atmospheric, satellite, and sruface observations not only improved the lead time of early warning for local severe convection, but also reduced missed detections. Under the control of the Western Pacific subtropical high, temperatures exceeding 35℃, combined with the perturbations in temperature and dew point temperature near the urban area, provided favorable thermodynamic conditions for the initiation of deep convection. Simultaneously, differences in land-water underlying characteristics led to higher temperatures on urban land compared to the temperature of adjacent Yangtze River water, thus, onshore winds were formed. On one hand, this process experienced abrupt changes in land-water underlying characteristics and complex urban land surfaces, causing convergence of wind direction and speed. On the other hand, the convergence of warm and cold air caused the enhanced instability of atmosphere. Further analysis reveals that the convergence of significant Q vector divergence at the surface persisted until surface precipitation occurred, indicating the generation of vertical upward motion due to the dynamic and thermodynamic forcings at the surface. Furthermore, the interaction between the sea breeze front and the convergence-induced updrafts from the urban heat island resulted in the local severe convection.
2025, 51(10):1182-1192.
DOI: 10.7519/j.issn.10000526.2025.041601
Abstract:
Based on the monthly precipitation of 643 stations in China, NCAR/NCEP reanalysis data and NOAA ERSST sea surface temperature (SST) data from 1961 to 2023, the impacts of early and late onset of El Nino on summer precipitation in China are analyzed. The results are as follows. Westerly wind anomalies in the equatorial West-Central Pacific are more pronounced in June-August of years with early El Nino onset than in years with late El Nino onset, resulting in a more obvious warming of SST in the equatorial East-Central Pacific in earlier onset years, and the SST in this period continues to rise. However, the positive anomaly of SST in the equatorial East-Central Pacific in the later onset years of El Nino is not obvious and changes slowly. There are obvious differences in summer precipitation in central and eastern China between the El Nino earlier and the El Nino later onset years, especially in July and August. In the El Nino earlier onset years, the Western North Pacific anomalous anticyclone (WNPAC) generally appears around August, the summer precipitation in central and eastern China is distributed in the “-+-” pattern from south to north, with more precipitation than normal in Jianghuai Region, and less precipitation than normal in other areas. In June, the West Pacific has an abnormal cyclone and the precipitation in most of China’s central and eastern parts is less than normal. In July, the abnormal cyclone in the West Pacific retreats southward significantly, the precipitation in most parts of the Jiangnan, Northwest and North China continues to be less than normal. And the abnormal anticyclone to the east of Japan significantly extends westward and develops southward, which makes the southeast coastal areas of China turn to be dominated by abnormal southerly winds, leading to excessive precipitation along the southern China coast and in Jianghuai Basin. In August, the cyclone in the Northwest Pacific turns into an anomalous anticyclone and WNPAC begins to appear, so the precipitation over the middle and lower reaches of the Yangtze River and most parts of its south is more than normal, while the precipitation in most parts of northern China is less than normal. In the later onset years of El Nino, WNPAC usually appears in October or later, and the West Pacific has an abnormal cyclone from June to August. The summer precipitation in the central and eastern regions of China is distributed in the “+-+” pattern from south to north, and the precipitation anomaly persistence characteristics of each month are obvious.
Based on the monthly precipitation of 643 stations in China, NCAR/NCEP reanalysis data and NOAA ERSST sea surface temperature (SST) data from 1961 to 2023, the impacts of early and late onset of El Nino on summer precipitation in China are analyzed. The results are as follows. Westerly wind anomalies in the equatorial West-Central Pacific are more pronounced in June-August of years with early El Nino onset than in years with late El Nino onset, resulting in a more obvious warming of SST in the equatorial East-Central Pacific in earlier onset years, and the SST in this period continues to rise. However, the positive anomaly of SST in the equatorial East-Central Pacific in the later onset years of El Nino is not obvious and changes slowly. There are obvious differences in summer precipitation in central and eastern China between the El Nino earlier and the El Nino later onset years, especially in July and August. In the El Nino earlier onset years, the Western North Pacific anomalous anticyclone (WNPAC) generally appears around August, the summer precipitation in central and eastern China is distributed in the “-+-” pattern from south to north, with more precipitation than normal in Jianghuai Region, and less precipitation than normal in other areas. In June, the West Pacific has an abnormal cyclone and the precipitation in most of China’s central and eastern parts is less than normal. In July, the abnormal cyclone in the West Pacific retreats southward significantly, the precipitation in most parts of the Jiangnan, Northwest and North China continues to be less than normal. And the abnormal anticyclone to the east of Japan significantly extends westward and develops southward, which makes the southeast coastal areas of China turn to be dominated by abnormal southerly winds, leading to excessive precipitation along the southern China coast and in Jianghuai Basin. In August, the cyclone in the Northwest Pacific turns into an anomalous anticyclone and WNPAC begins to appear, so the precipitation over the middle and lower reaches of the Yangtze River and most parts of its south is more than normal, while the precipitation in most parts of northern China is less than normal. In the later onset years of El Nino, WNPAC usually appears in October or later, and the West Pacific has an abnormal cyclone from June to August. The summer precipitation in the central and eastern regions of China is distributed in the “+-+” pattern from south to north, and the precipitation anomaly persistence characteristics of each month are obvious.
2025, 51(10):1193-1202.
DOI: 10.7519/j.issn.1000-0526.2025.022601
Abstract:
A cumuliform cloud with supercooled water (shortened as supercooled cumuliform cloud) is the condition required for the icing test flight. On the basis of the cloud phase state, cloud classification and liquid water top height data from CloudSat-CALIPSO cloud products and the air temperature from ERA5 reanalysis data and focusing on the local solar afternoon data with good interannual continuity, we construct the historical supercooled cloud sample dataset over China during 2006-2019, and analyze the spatio-temporal distribution characteristics of supercooled cumuliform clouds. The supercooled cumuliform clouds in China mostly occur in the eastern part of the Qinghai-Xizang Plateau and extend to central China via the Yunnan-Guizhou-Sichuan region, with an annual average occurrence frequency of 0.4. The high-value areas of the occurrence frequency of supercooled cumuliform clouds are more westward than that of supercooled stratiform cloud and the occurrence frequency is higher. The occurrence frequencies of the four types of supercooled cumuliform clouds in descending order were as follows: altocumulus over Yunnan, Central China and East China; stratocumulus over eastern Qinghai-Xizang Plateau, Sichuan, the eastern sea surface of China and outside the northern boundary of China; cumulus over the Qinghai-Xizang Plateau; and deep convection over southwestern Yunnan, Southeast China, and the eastern sea surface of China. In winter, there are three high-value centers of the occurrence frequency of supercooled cumuliform clouds from Sichuan Basin to Guizhou, the ocean over eastern China, and the Sea of Japan, while the high-value center of the occurrence frequency of supercooled cumuliform clouds in summer extends from the eastern part of the Qinghai-Xizang Plateau to other locations on the plateau and the surrounding mountainous areas. In addition, the interannual variation of supercooled cumuliform clouds shows a significantly increasing trend in January in Central China, the west of Northwest China and the west of the Qinghai-Xizang Plateau.
A cumuliform cloud with supercooled water (shortened as supercooled cumuliform cloud) is the condition required for the icing test flight. On the basis of the cloud phase state, cloud classification and liquid water top height data from CloudSat-CALIPSO cloud products and the air temperature from ERA5 reanalysis data and focusing on the local solar afternoon data with good interannual continuity, we construct the historical supercooled cloud sample dataset over China during 2006-2019, and analyze the spatio-temporal distribution characteristics of supercooled cumuliform clouds. The supercooled cumuliform clouds in China mostly occur in the eastern part of the Qinghai-Xizang Plateau and extend to central China via the Yunnan-Guizhou-Sichuan region, with an annual average occurrence frequency of 0.4. The high-value areas of the occurrence frequency of supercooled cumuliform clouds are more westward than that of supercooled stratiform cloud and the occurrence frequency is higher. The occurrence frequencies of the four types of supercooled cumuliform clouds in descending order were as follows: altocumulus over Yunnan, Central China and East China; stratocumulus over eastern Qinghai-Xizang Plateau, Sichuan, the eastern sea surface of China and outside the northern boundary of China; cumulus over the Qinghai-Xizang Plateau; and deep convection over southwestern Yunnan, Southeast China, and the eastern sea surface of China. In winter, there are three high-value centers of the occurrence frequency of supercooled cumuliform clouds from Sichuan Basin to Guizhou, the ocean over eastern China, and the Sea of Japan, while the high-value center of the occurrence frequency of supercooled cumuliform clouds in summer extends from the eastern part of the Qinghai-Xizang Plateau to other locations on the plateau and the surrounding mountainous areas. In addition, the interannual variation of supercooled cumuliform clouds shows a significantly increasing trend in January in Central China, the west of Northwest China and the west of the Qinghai-Xizang Plateau.
2025, 51(10):1203-1214.
DOI: 10.7519/j.issn.1000-0526.2025.041801
Abstract:
Studying the drought condition in the water source area and receiving area of the Middle Route Project of South-to-North Water Diversion Project is of great significance for the water resource scheduling and operation management of the project. Based on the NCEP-NCAR reanalysis data and the daily average temperature, precipitation, and meteorological drought composite index of all meteorological stations in the water source area and receiving area of Middle Route Project of South-to-North Water Diversion Project from 1961 to 2023, this article conducts identification and assessment of regional drought processes in water source area and receiving area. The results show that the annual values of drought days in the water source area and receiving area are 101 d and 114 d, respectively, presenting an overall spatial distribution feature of “more in the middle and less at both ends”. The northern part of Henan and the southern part of Hebei in the water receiving area are high-value areas of drought days. The number of drought days in most of the water source areas, most of the water receiving areas in Henan and eastern Hebei is increasing, while the number of drought days in most of the water receiving areas in the northern, western and southern parts of Hebei, Beijing and Tianjin is decreasing. Using the dynamic regional drought process identification method, a total of 97 regional drought processes have been identified in the study area since 1961. Using the percentile method to divide the intensity index of regional drought processes, we obtain the threshold values corresponding to different intensity levels, and a total of 4 “extremely heavy”, 15 “heavy”, 30 “relatively heavy”, and 48 “moderate” regional drought processes in the study area. The heaviest 3 regional drought processes occurred in 1968, 2001 and 1997, and the differences in circulation characteristics led to significant differences in the spatial and temporal distribution of drought days and the proportion of drought stations at different levels among the three processes. Among the 97 regional drought processes in the study area, 54.6% were droughts in the water source area but not in the water receiving area, which is beneficial for engineering water diversion. At the same time, in some years, the entire region is uniformly dry or the water source area is dry while the water receiving area is not dry. This is not conducive to engineering water diversion. Therefore, for the water resource scheduling of the Middle Route Project of South-to-North Water Diversion Project, the targeted water diversion work needs to be carried out based on the actual situation.
Studying the drought condition in the water source area and receiving area of the Middle Route Project of South-to-North Water Diversion Project is of great significance for the water resource scheduling and operation management of the project. Based on the NCEP-NCAR reanalysis data and the daily average temperature, precipitation, and meteorological drought composite index of all meteorological stations in the water source area and receiving area of Middle Route Project of South-to-North Water Diversion Project from 1961 to 2023, this article conducts identification and assessment of regional drought processes in water source area and receiving area. The results show that the annual values of drought days in the water source area and receiving area are 101 d and 114 d, respectively, presenting an overall spatial distribution feature of “more in the middle and less at both ends”. The northern part of Henan and the southern part of Hebei in the water receiving area are high-value areas of drought days. The number of drought days in most of the water source areas, most of the water receiving areas in Henan and eastern Hebei is increasing, while the number of drought days in most of the water receiving areas in the northern, western and southern parts of Hebei, Beijing and Tianjin is decreasing. Using the dynamic regional drought process identification method, a total of 97 regional drought processes have been identified in the study area since 1961. Using the percentile method to divide the intensity index of regional drought processes, we obtain the threshold values corresponding to different intensity levels, and a total of 4 “extremely heavy”, 15 “heavy”, 30 “relatively heavy”, and 48 “moderate” regional drought processes in the study area. The heaviest 3 regional drought processes occurred in 1968, 2001 and 1997, and the differences in circulation characteristics led to significant differences in the spatial and temporal distribution of drought days and the proportion of drought stations at different levels among the three processes. Among the 97 regional drought processes in the study area, 54.6% were droughts in the water source area but not in the water receiving area, which is beneficial for engineering water diversion. At the same time, in some years, the entire region is uniformly dry or the water source area is dry while the water receiving area is not dry. This is not conducive to engineering water diversion. Therefore, for the water resource scheduling of the Middle Route Project of South-to-North Water Diversion Project, the targeted water diversion work needs to be carried out based on the actual situation.
2025, 51(10):1215-1225.
DOI: 10.7519/j.issn.1000-0526.2025.040301
Abstract:
In recent years, the interaction between aerosols and thunderstorm electrification has emerged as a focal point in academic research. Homogeneous nucleation of soluble aerosol droplets and heterogeneous nucleation of ice nuclei are two primary sources for ice crystal formation. The size and concentration of ice crystals in thunderstorms significantly influence charge generation and distribution, and are critical factors in lightning events. This paper employs a three-dimensional thunderstorm model to investigate the impact of three distinct ice nucleation schemes on lightning discharge characteristics, focusing on a mountain weak thunderstorm case. The results demonstrate that homogeneous nucleation generates a substantial number of ice crystals in the low-temperature zones at the cloud top, resulting in prolonged discharge duration within the thunderstorm. The charge structure is predominantly dipolar, with a lower lightning frequency, primarily consisting of cloud flashes originating from higher altitudes. In contrast, heterogeneous nucleation forms ice crystals in high-temperature zones, leading to an earlier charging process in thunderstorms. Ice crystals in these zones readily meet charge reversal conditions, significantly increasing the negative non-inductive charging rate and favoring the formation of tripolar charge structures. Under these conditions, lightning occurs earlier and initiates from relatively lower altitudes, with heterogeneous nucleation facilitating lightning occurrence. When both homogeneous and heterogeneous nucleation processes occur simultaneously, the thunderstorm charging process intensifies, resulting in a high lightning frequency. Furthermore, both nucleation processes advance the initial lightning occurrence time and expand the height range of the initial lightning trigger points. The tripolar charge structure promotes the occurrence of a substantial number of negative cloud-to-ground flashes.
In recent years, the interaction between aerosols and thunderstorm electrification has emerged as a focal point in academic research. Homogeneous nucleation of soluble aerosol droplets and heterogeneous nucleation of ice nuclei are two primary sources for ice crystal formation. The size and concentration of ice crystals in thunderstorms significantly influence charge generation and distribution, and are critical factors in lightning events. This paper employs a three-dimensional thunderstorm model to investigate the impact of three distinct ice nucleation schemes on lightning discharge characteristics, focusing on a mountain weak thunderstorm case. The results demonstrate that homogeneous nucleation generates a substantial number of ice crystals in the low-temperature zones at the cloud top, resulting in prolonged discharge duration within the thunderstorm. The charge structure is predominantly dipolar, with a lower lightning frequency, primarily consisting of cloud flashes originating from higher altitudes. In contrast, heterogeneous nucleation forms ice crystals in high-temperature zones, leading to an earlier charging process in thunderstorms. Ice crystals in these zones readily meet charge reversal conditions, significantly increasing the negative non-inductive charging rate and favoring the formation of tripolar charge structures. Under these conditions, lightning occurs earlier and initiates from relatively lower altitudes, with heterogeneous nucleation facilitating lightning occurrence. When both homogeneous and heterogeneous nucleation processes occur simultaneously, the thunderstorm charging process intensifies, resulting in a high lightning frequency. Furthermore, both nucleation processes advance the initial lightning occurrence time and expand the height range of the initial lightning trigger points. The tripolar charge structure promotes the occurrence of a substantial number of negative cloud-to-ground flashes.
2025, 51(10):1226-1236.
DOI: 10.7519/j.issn.1000-0526.2025.080301
Abstract:
In this paper, a parallel chunking processing scheme is designed for the compression/decompression process by adopting OpenMP technology based on a conventional PC workstation as a benchmark. The compression and decompression time of the data can be reduced to about 1/5 and 1/8 of the single-threaded one when the number of chunks reaches 16 under a 12-core/24-threaded CPU. For the decoding process, the results of parallel processing by PPI, radial and distance banks are compared, and it is found that the parallel processing scheme on radial is optimal, for it can reduce the decoding time to about 1/8 of the single-threaded one. Through the application of the above two parallel optimization techniques, the pressure of radar base data in data transmission and preprocessing can be significantly reduced, and the dataloading performance of the radar software can also be enhanced to improve the interactive experience of the radar analysis software based on base data.
In this paper, a parallel chunking processing scheme is designed for the compression/decompression process by adopting OpenMP technology based on a conventional PC workstation as a benchmark. The compression and decompression time of the data can be reduced to about 1/5 and 1/8 of the single-threaded one when the number of chunks reaches 16 under a 12-core/24-threaded CPU. For the decoding process, the results of parallel processing by PPI, radial and distance banks are compared, and it is found that the parallel processing scheme on radial is optimal, for it can reduce the decoding time to about 1/8 of the single-threaded one. Through the application of the above two parallel optimization techniques, the pressure of radar base data in data transmission and preprocessing can be significantly reduced, and the dataloading performance of the radar software can also be enhanced to improve the interactive experience of the radar analysis software based on base data.
2025, 51(10):1237-1248.
DOI: 10.7519/j.issn.1000-0526.2025.062601
Abstract:
Taking into account the relationships between model temperature forecasts, model topography, observed temperatures and actual topography, this paper designs a dynamically approximated vertical rate correction method for the 2 m temperature that evolves over space and time. A correction test is conducted for Chongqing in 2023. The evaluation results of ECMWF model forecasts show that the spatial distribution of forecast skill for maximum and minimum 2 m temperatures is similar, but forecast skill for maximum temperature is significantly weaker than for minimum temperature, and deteriorates with increasing forecast lead time. A close correlation is found between model topographic elevation bias and temperature forecast bias. Areas with smaller elevation bias tend to exhibit better forecast skill, and vice versa. Comparative research reveals that the correction scheme based on dynamically approximated vertical rate signifi-cantly outperforms the scheme based on the constant vertical rate. Both schemes can improve the ECMWF model temperature forecasts, with better correction performance for maximum temperatures than for minimum temperatures. Compared to the raw model forecasts, the corrected results based on dynamically approximated vertical rate have increased the 10 d average forecast accuracy of maximum and minimum temperatures by 12.71% and 8.30%, respectively, and reduced the mean absolute error by 0.68℃ and 0.30℃, respectively. The monthly average forecast accuracy of the maximum temperature for 24 h forecast lead time has increased by 20.34% and the minimum temperature has increased by 14.44%. Overall, the corrected temperature forecasts are more stable. The correction scheme based on dynamically approximated vertical rate can effectively reduce the temperature forecast bias. The greater the model topographic elevation bias, the smaller the amplitude of weather process fluctuation, and the more obvious the correction performance.
Taking into account the relationships between model temperature forecasts, model topography, observed temperatures and actual topography, this paper designs a dynamically approximated vertical rate correction method for the 2 m temperature that evolves over space and time. A correction test is conducted for Chongqing in 2023. The evaluation results of ECMWF model forecasts show that the spatial distribution of forecast skill for maximum and minimum 2 m temperatures is similar, but forecast skill for maximum temperature is significantly weaker than for minimum temperature, and deteriorates with increasing forecast lead time. A close correlation is found between model topographic elevation bias and temperature forecast bias. Areas with smaller elevation bias tend to exhibit better forecast skill, and vice versa. Comparative research reveals that the correction scheme based on dynamically approximated vertical rate signifi-cantly outperforms the scheme based on the constant vertical rate. Both schemes can improve the ECMWF model temperature forecasts, with better correction performance for maximum temperatures than for minimum temperatures. Compared to the raw model forecasts, the corrected results based on dynamically approximated vertical rate have increased the 10 d average forecast accuracy of maximum and minimum temperatures by 12.71% and 8.30%, respectively, and reduced the mean absolute error by 0.68℃ and 0.30℃, respectively. The monthly average forecast accuracy of the maximum temperature for 24 h forecast lead time has increased by 20.34% and the minimum temperature has increased by 14.44%. Overall, the corrected temperature forecasts are more stable. The correction scheme based on dynamically approximated vertical rate can effectively reduce the temperature forecast bias. The greater the model topographic elevation bias, the smaller the amplitude of weather process fluctuation, and the more obvious the correction performance.
YANG Rongfang
,
GUO Jianping
,
KONG Fanchao
,
MENG Deli
,
ZHANG Zhen
,
GUO Xiaoran
,
SHAN Yufeng
,
DENG Jianbo
2025, 51(10):1249-1260.
DOI: 10.7519/j.issn.1000-0526.2025.060901
Abstract:
In this study, we analyze the evolution of the dynamical field before the occurrence of convection by using the dynamical parameter profiles below 4 km inverted from the wind profile radar mesoscale network from April to September during 2023-2024. The results show that before the convection triggering, the dynamical field is characterized by a vertical upward motion configuration with low-level convergence and high-level divergence. There exists the presence of positive time-lag correlations between area averaged rainfall and convergence in the lower to mid-troposphere. During the 30 min before precipitation, horizontal divergence is less than -5×10-5 s-1, with the convergence thickness below 1 km deepening, which means that the continuously enhanced convergence and upward motion favors the occurrence of convection. The horizontal convergence intensity sustained to be greater than 50×10-5 s-1 in the 30 min prior to precipitation is used as an indicator for the early signal of convection triggering. Among 763 precipitation events, the accuracy rate of effective identification of precipitation events is 72.3%. These findings can provide an important reference for quantitatively analyzing the early warning of severe convection in Beijing-Tianjin-Hebei Region.
In this study, we analyze the evolution of the dynamical field before the occurrence of convection by using the dynamical parameter profiles below 4 km inverted from the wind profile radar mesoscale network from April to September during 2023-2024. The results show that before the convection triggering, the dynamical field is characterized by a vertical upward motion configuration with low-level convergence and high-level divergence. There exists the presence of positive time-lag correlations between area averaged rainfall and convergence in the lower to mid-troposphere. During the 30 min before precipitation, horizontal divergence is less than -5×10-5 s-1, with the convergence thickness below 1 km deepening, which means that the continuously enhanced convergence and upward motion favors the occurrence of convection. The horizontal convergence intensity sustained to be greater than 50×10-5 s-1 in the 30 min prior to precipitation is used as an indicator for the early signal of convection triggering. Among 763 precipitation events, the accuracy rate of effective identification of precipitation events is 72.3%. These findings can provide an important reference for quantitatively analyzing the early warning of severe convection in Beijing-Tianjin-Hebei Region.
2025, 51(10):1261-1271.
DOI: 10.7519/j.issn.10000526.2025.070802
Abstract:
Based on highprecision online atmospheric CO2 concentration measurements from the Shenyang Urban Ecological Station from June 2023 to May 2024, the REBS （robust extraction of baseline signal） algorithm is employed to separate regional background and pollution data. The influence of regional transport on atmospheric CO2 concentrations in Shenyang is analyzed using surface wind field data and MeteoInfo statistical software. The contributions of fossil fuel combustion emissions and ecosystem emissions/absorption to CO2 concentration are estimated according to carbon conservation principles. The results show that the average CO2 concentration at Shenyang Urban Ecological Station is 477.2×10-6, with background and pollution concentrations averaged to be 474.9×10-6 and 519.4×10-6, respectively. Highconcentration CO2 air masses affecting Shenyang originate from the southwest in spring and summer, and from northwest and southwest in winter. The potential CO2 emission source regions throughout the year are mainly distributed in most parts of Liaoning and Jilin provinces, southern Heilongjiang, eastern Inner Mongolia, BeijingTianjinHebei Region, Shandong Peninsula, and the Yellow Sea and Bohai Sea areas. Compared to fossil fuel combustion emission in other seasons, the fossil fuel combustion emission contributes more significantly to the atmospheric CO2 concentration in Shenyang during autumn and winter.
Based on highprecision online atmospheric CO2 concentration measurements from the Shenyang Urban Ecological Station from June 2023 to May 2024, the REBS （robust extraction of baseline signal） algorithm is employed to separate regional background and pollution data. The influence of regional transport on atmospheric CO2 concentrations in Shenyang is analyzed using surface wind field data and MeteoInfo statistical software. The contributions of fossil fuel combustion emissions and ecosystem emissions/absorption to CO2 concentration are estimated according to carbon conservation principles. The results show that the average CO2 concentration at Shenyang Urban Ecological Station is 477.2×10-6, with background and pollution concentrations averaged to be 474.9×10-6 and 519.4×10-6, respectively. Highconcentration CO2 air masses affecting Shenyang originate from the southwest in spring and summer, and from northwest and southwest in winter. The potential CO2 emission source regions throughout the year are mainly distributed in most parts of Liaoning and Jilin provinces, southern Heilongjiang, eastern Inner Mongolia, BeijingTianjinHebei Region, Shandong Peninsula, and the Yellow Sea and Bohai Sea areas. Compared to fossil fuel combustion emission in other seasons, the fossil fuel combustion emission contributes more significantly to the atmospheric CO2 concentration in Shenyang during autumn and winter.
2025, 51(10):1272-1281.
DOI: 10.7519/j.issn.10000526.2025.101601
Abstract:
During spring (March to May) of 2025, the mean temperature in China was 0.9℃ higher than the climatological mean, ranking as the fourth warmest since 1961. The spring mean precipitation was close to normal, exhibiting distinct intraseasonal variability characteristics. In southern China, due to the less than normal precipitation in the early spring, severe meteorological drought occurred, but precipitation increased in the late spring, leading to flood disasters in some regions. In northern China, from eastern Northwest China to western HuangHuai Region, severe meteorological drought occurred because of much less precipitation from April to May. The intraseasonal transition of precipitation in southern China was mainly caused by the combined effects of the previous winter La Nina state and the intraseasonal warming of the tropical Indian Ocean sea surface temperature in spring. In the early spring, the Indian Ocean sea surface temperature was slightly colder, showing a response to the winter La Nina state. This was conducive to the emergence of an abnormal cyclonic circulation in the Northwest Pacific, leading to less precipitation in southern China. However, in the late spring, the pronounced warming of the Indian Ocean sea surface temperature favored an abnormal anticyclone in the Northwest Pacific, leading to the increased precipitation in southern China. The drought in the Northwest China to HuangHuai regions in April and May was mainly the result of the stable maintenance of the atmospheric Eurasian teleconnection pattern at midtohigh latitudes.
During spring (March to May) of 2025, the mean temperature in China was 0.9℃ higher than the climatological mean, ranking as the fourth warmest since 1961. The spring mean precipitation was close to normal, exhibiting distinct intraseasonal variability characteristics. In southern China, due to the less than normal precipitation in the early spring, severe meteorological drought occurred, but precipitation increased in the late spring, leading to flood disasters in some regions. In northern China, from eastern Northwest China to western HuangHuai Region, severe meteorological drought occurred because of much less precipitation from April to May. The intraseasonal transition of precipitation in southern China was mainly caused by the combined effects of the previous winter La Nina state and the intraseasonal warming of the tropical Indian Ocean sea surface temperature in spring. In the early spring, the Indian Ocean sea surface temperature was slightly colder, showing a response to the winter La Nina state. This was conducive to the emergence of an abnormal cyclonic circulation in the Northwest Pacific, leading to less precipitation in southern China. However, in the late spring, the pronounced warming of the Indian Ocean sea surface temperature favored an abnormal anticyclone in the Northwest Pacific, leading to the increased precipitation in southern China. The drought in the Northwest China to HuangHuai regions in April and May was mainly the result of the stable maintenance of the atmospheric Eurasian teleconnection pattern at midtohigh latitudes.
2025, 51(10):1282-1292.
DOI: 10.7519/j.issn.1000-0526.2025.101401
Abstract:
The main characteristics of the general circulation in July 2025 are that the mid-to-high latitudes of the Northern Hemisphere exhibited a multi-wave pattern, with positive geopotential height anomalies dominating the region from the West Siberian Plain to Japan. The western Pacific subtropical high was located farther north and was significantly stronger than usual. The national average temperature reached 23.6℃, which is 1.5℃ higher than the climatological average of 22.1℃, marking the highest value since 1961. The number of high-temperature days was 6.1 days, exceeding the climatological average of 3.6 days by 2.5 days, also the highest since 1961. The national average precipitation was 115.5 mm, 5.1% lower than the climatological average of 121.7 mm. During the month, there occurred three typhoons, six heavy rainfall events, three high-temperature episodes and nine severe convective weather processes, which caused frequent extreme weather events across multiple regions. In addition, this article provides a brief analysis on the mechanisms and forecasting challenges associated with the heavy rainfall triggered by Typhoon Wipha, and also on the extreme precipitation event in North China from 23 to 29 July 2025.
The main characteristics of the general circulation in July 2025 are that the mid-to-high latitudes of the Northern Hemisphere exhibited a multi-wave pattern, with positive geopotential height anomalies dominating the region from the West Siberian Plain to Japan. The western Pacific subtropical high was located farther north and was significantly stronger than usual. The national average temperature reached 23.6℃, which is 1.5℃ higher than the climatological average of 22.1℃, marking the highest value since 1961. The number of high-temperature days was 6.1 days, exceeding the climatological average of 3.6 days by 2.5 days, also the highest since 1961. The national average precipitation was 115.5 mm, 5.1% lower than the climatological average of 121.7 mm. During the month, there occurred three typhoons, six heavy rainfall events, three high-temperature episodes and nine severe convective weather processes, which caused frequent extreme weather events across multiple regions. In addition, this article provides a brief analysis on the mechanisms and forecasting challenges associated with the heavy rainfall triggered by Typhoon Wipha, and also on the extreme precipitation event in North China from 23 to 29 July 2025.
Mobile website
® 2025 All Rights Reserved
Supported by:Beijing E-Tiller Technology Development Co., Ltd.
ISSN:1000-0526 CN:11-2282/P