ISSN 1000-0526
CN 11-2282/P
CN 11-2282/P
Volume 50,Issue 3,2024 Table of Contents
2024, 50(3):265-274.
DOI: 10.7519/j.issn.1000-0526.2024.030402
Abstract:
Warming-characterized global climate change has seriously threatened the global food security. High-standard farmland construction, as an important measure for agriculture to adapt to climate change, has been popularized and implemented in China. In order to support the high-standard farmland production under the influence of climate warming, this study investigates the history of the international land consolidation and the high-standard farmland construction in China, reviews the latest research progress in four key areas, including the suitability assessment of high-standard farmland, the grain crop production effect of land element configuration, the supervision and management of high-standard farmland, and the benefit evaluation of high-standard farmland construction, pointing out the current shortage of research related to meteorological support for high-standard farmland production. Focusing on the requirements of ensuring grain harvest in high-standard farmland under both drought and waterlogging conditions, possessing strong disaster resilience, and maintaining a good eco-environment, the following main tasks are proposed for high-standard farmland production with meteorological support: the interaction of farmland ecosystem-climate-water resources and the water-saving irrigation in farmland; precise monitoring and simulation of meteorological disasters, and rapid attribution analysis of major grain crops; detection of eco-meteorological risk sensitive factors in farmland and their meteorological monitoring and evaluation. These tasks would promote the quality and efficiency of meteorological services for agriculture, and support the high-yield and efficiency of high-standard farmland.
Warming-characterized global climate change has seriously threatened the global food security. High-standard farmland construction, as an important measure for agriculture to adapt to climate change, has been popularized and implemented in China. In order to support the high-standard farmland production under the influence of climate warming, this study investigates the history of the international land consolidation and the high-standard farmland construction in China, reviews the latest research progress in four key areas, including the suitability assessment of high-standard farmland, the grain crop production effect of land element configuration, the supervision and management of high-standard farmland, and the benefit evaluation of high-standard farmland construction, pointing out the current shortage of research related to meteorological support for high-standard farmland production. Focusing on the requirements of ensuring grain harvest in high-standard farmland under both drought and waterlogging conditions, possessing strong disaster resilience, and maintaining a good eco-environment, the following main tasks are proposed for high-standard farmland production with meteorological support: the interaction of farmland ecosystem-climate-water resources and the water-saving irrigation in farmland; precise monitoring and simulation of meteorological disasters, and rapid attribution analysis of major grain crops; detection of eco-meteorological risk sensitive factors in farmland and their meteorological monitoring and evaluation. These tasks would promote the quality and efficiency of meteorological services for agriculture, and support the high-yield and efficiency of high-standard farmland.
2024, 50(3):275-290.
DOI: 10.7519/j.issn.1000-0526.2024.011301
Abstract:
Research on the South China rainstorms in the first rainy season is not only a hot spot but also a difficulty in atmospheric science field. The South China shear line is an important weather system in South China, which is closely related to rainstorms in the South China first rainy season. In order to improve the forecasting ability of rainstorm in South China, deepen the understanding of the South China shear line, this paper systematically reviews the related researches on the South China shear line, including the definition, structure, formation and developing mechanisms, influence and interaction with other weather systems of the South China shear line. Meanwhile, by combining the reviews with the actual forecasting operation, we also propose some scientific issues worthy of further research.
Research on the South China rainstorms in the first rainy season is not only a hot spot but also a difficulty in atmospheric science field. The South China shear line is an important weather system in South China, which is closely related to rainstorms in the South China first rainy season. In order to improve the forecasting ability of rainstorm in South China, deepen the understanding of the South China shear line, this paper systematically reviews the related researches on the South China shear line, including the definition, structure, formation and developing mechanisms, influence and interaction with other weather systems of the South China shear line. Meanwhile, by combining the reviews with the actual forecasting operation, we also propose some scientific issues worthy of further research.
2024, 50(3):291-302.
DOI: 10.7519/j.issn.1000-0526.2023.122001
Abstract:
This article analyzes the vertical variation patterns of the echo intensity (Z), radial velocity (Vr), and velocity spectral width (Sw) of the cloud radar before and after two precipitation processes, using high-resolution vertical observation data obtained from the newly built Ka-band millimeter wave cloud radar at Lijiang Station, combined with minutely data from ground automatic weather stations and raindrop spectra at the same site, conventional sounding data, and intensity echoes from nearby C-band weather radar. Analysis shows that during weak precipitation, the vertical variation of cloud radar Z is not significant, but there is a clear boundary layer (melting layer) at a slightly lower position of the 0℃ layer for Vr and Sw values. After particles pass through the melting layer, Vr and Sw rapidly increase. This change is mainly caused by the phase state of particles changing from solid to liquid. The height of the bright band in the 0℃ layer can be identified by the position of the sudden changes in Vr and Sw values.From the time-height maps of C-band weather radar echo intensity, profile, and cloud radar position, we can see a significant difference in intensity and height between the echoes of drizzle and light rain. The height of the echoes of drizzle is lower and weaker than that of light rain. Compared to cloud radar, C-band radar cannot observe higher clouds and weak precipitation echoes at longer distances. Due to the different scattering of electromagnetic waves of different wavelengths by the same particle, the Z changes observed in the vertical direction by the two radars are different. Compared with weak precipitation echoes, during strong precipitation cloud radar shows a gap in Z, Vr has a significant positive value above the 0℃ layer (Vr for weak precipitation is negative), and Sw becomes larger above the 0℃ layer (during weak precipitation, Sw values are smaller above the 0℃ layer and larger below the 0℃ layer). During heavy rainfall, from the C-band radar echo intensity time-height map, the vertical direction echo intensity changes significantly, and at the same time, the variation of echo intensity from ground to air gradually decreases. The intensity of the same altitude layer also varies at different times, and the echo during the rain attenuation gap period of cloud radar is significantly stronger than that in other periods. The case study shows that if precipitation occurs with an intensity of less than 0.3 mm per minute, cloud radar can observe complete cloud information; if precipitation with a minimum rainfall intensity of 0.5 mm or more occurs, cloud radar will experience severe rain attenuation and cannot observe complete cloud information
This article analyzes the vertical variation patterns of the echo intensity (Z), radial velocity (Vr), and velocity spectral width (Sw) of the cloud radar before and after two precipitation processes, using high-resolution vertical observation data obtained from the newly built Ka-band millimeter wave cloud radar at Lijiang Station, combined with minutely data from ground automatic weather stations and raindrop spectra at the same site, conventional sounding data, and intensity echoes from nearby C-band weather radar. Analysis shows that during weak precipitation, the vertical variation of cloud radar Z is not significant, but there is a clear boundary layer (melting layer) at a slightly lower position of the 0℃ layer for Vr and Sw values. After particles pass through the melting layer, Vr and Sw rapidly increase. This change is mainly caused by the phase state of particles changing from solid to liquid. The height of the bright band in the 0℃ layer can be identified by the position of the sudden changes in Vr and Sw values.From the time-height maps of C-band weather radar echo intensity, profile, and cloud radar position, we can see a significant difference in intensity and height between the echoes of drizzle and light rain. The height of the echoes of drizzle is lower and weaker than that of light rain. Compared to cloud radar, C-band radar cannot observe higher clouds and weak precipitation echoes at longer distances. Due to the different scattering of electromagnetic waves of different wavelengths by the same particle, the Z changes observed in the vertical direction by the two radars are different. Compared with weak precipitation echoes, during strong precipitation cloud radar shows a gap in Z, Vr has a significant positive value above the 0℃ layer (Vr for weak precipitation is negative), and Sw becomes larger above the 0℃ layer (during weak precipitation, Sw values are smaller above the 0℃ layer and larger below the 0℃ layer). During heavy rainfall, from the C-band radar echo intensity time-height map, the vertical direction echo intensity changes significantly, and at the same time, the variation of echo intensity from ground to air gradually decreases. The intensity of the same altitude layer also varies at different times, and the echo during the rain attenuation gap period of cloud radar is significantly stronger than that in other periods. The case study shows that if precipitation occurs with an intensity of less than 0.3 mm per minute, cloud radar can observe complete cloud information; if precipitation with a minimum rainfall intensity of 0.5 mm or more occurs, cloud radar will experience severe rain attenuation and cannot observe complete cloud information
2024, 50(3):303-317.
DOI: 10.7519/j.issn.1000-0526.2023.111801
Abstract:
Mêdog located at the entrance of the water vapor channel of the Yarlung Zangbo Grand Canyon, has the largest rainfall totals over the Tibetan Plateau. In this article, the monthly and diurnal variation characteristics of precipitation in Mêdog are analyzed with the automatic rain gauge data collected from 2019 to 2021. Based on the observations from precipitation phenomenometer and X-band dual polarization phased array radar, the evolution characteristics of two heavy precipitation events that occurred in Mêdog are explored. The results show that precipitation frequently occurs in Mêdog with rainy days exceeding 70% of the whole year and light rain less than 5 mm·h-1 as dominant rainfall type. The occurrence frequency of light rain with daily rainfall less than 10 mm is the highest, while moderate rain with daily rainfall between 10 mm and 25 mm is the largest contributor to rainfall amount. The Mêdog precipitation features obvious monthly and daily variations. The highest occurrence frequency of rainfall is in the monsoon season from June to September, which is attributed to the warm and humid airflow from the Indian Ocean. Furthermore, rainfall frequently occurs at night due to the mountain-valley wind, which is related to the valley terrain of Mêdog. In terms of the evolution of heavy rainfall events, the systematic heavy rainfall events under the effect of Tibetan Plateau vortex and South Branch Trough are characterized by expansive area and long duration. The rainfall event is dominated by small raindrop less than 2 mm, and the radar reflectivity factor is generally smaller than 35 dBz. However, local short-duration convective precipitation event forced by topographic has a wider raindrop size distribution width and higher raindrop concentration. Raindrops larger than 2 mm in diameter contribute maximum rainfall amount with radar reflectivity factor of convective core exceeding 45 dBz. The backward propagation of the storm generates a “train effect” during the heavy rainfall event of this heavy rainfall event.
Mêdog located at the entrance of the water vapor channel of the Yarlung Zangbo Grand Canyon, has the largest rainfall totals over the Tibetan Plateau. In this article, the monthly and diurnal variation characteristics of precipitation in Mêdog are analyzed with the automatic rain gauge data collected from 2019 to 2021. Based on the observations from precipitation phenomenometer and X-band dual polarization phased array radar, the evolution characteristics of two heavy precipitation events that occurred in Mêdog are explored. The results show that precipitation frequently occurs in Mêdog with rainy days exceeding 70% of the whole year and light rain less than 5 mm·h-1 as dominant rainfall type. The occurrence frequency of light rain with daily rainfall less than 10 mm is the highest, while moderate rain with daily rainfall between 10 mm and 25 mm is the largest contributor to rainfall amount. The Mêdog precipitation features obvious monthly and daily variations. The highest occurrence frequency of rainfall is in the monsoon season from June to September, which is attributed to the warm and humid airflow from the Indian Ocean. Furthermore, rainfall frequently occurs at night due to the mountain-valley wind, which is related to the valley terrain of Mêdog. In terms of the evolution of heavy rainfall events, the systematic heavy rainfall events under the effect of Tibetan Plateau vortex and South Branch Trough are characterized by expansive area and long duration. The rainfall event is dominated by small raindrop less than 2 mm, and the radar reflectivity factor is generally smaller than 35 dBz. However, local short-duration convective precipitation event forced by topographic has a wider raindrop size distribution width and higher raindrop concentration. Raindrops larger than 2 mm in diameter contribute maximum rainfall amount with radar reflectivity factor of convective core exceeding 45 dBz. The backward propagation of the storm generates a “train effect” during the heavy rainfall event of this heavy rainfall event.
2024, 50(3):318-330.
DOI: 10.7519/j.issn.1000-0526.2023.051201
Abstract:
In this study, based on precipitation observation data and ERA5 reanalysis data of Haituo Mountain from 1 January to 15 March of 2019-2021, the 34 winter precipitation processes in Haituo Mountain were classified. The characteristics of observed precipitation at different altitudes under different weather types were analyzed statistically. The results were as follows. According to the influence of weather system and terrain, the winter precipitation in Haituo Mountain can be divided into four weather types: northerly airflow type, easterly airflow type, low eddy trough type, and backflow low eddy trough type. Under different weather types, the direction and intensity of the airflow, the vertical distribution of water vapor and other conditions below the topographic height of Haituo Mountain as well as the interaction with the topographic conditions, make significant differences in precipitation and its duration between different altitudes. The northerly airflow type is controlled by the strong northerly airflow in the whole layer behind the 500 hPa trough, forming the airflow passing over mountain, and the precipitation is concentrated in the high-altitude area. The easterly airflow type is affected by the easterly airflow at the lower level, and the precipitation is concentrated in the low-altitude area. The above two weather types have no synoptic-scale system to accompany, and are dominated by topographic forcing, so the precipitation is small in amount, lasting for relatively short time. The low eddy trough type is affected by the high-altitude eastward movement of low trough, accompanied by the low level southwest airflow, which makes more precipitation at high-altitude area, and this type is also the most frequent weather type in Haituo Mountain in winter. Backflow low eddy trough type is affected by the low trough, with easterly backflow before precipitation to humidify the lower level and play a role of cold cushion, so the precipitation in low-altitude area is more. The above two weather types have synoptic-scale systems, superimposed by the topographic effect of Haituo Mountain terrain, which causes significant precipitation and its long duration, affecting the game run. The above results have been applied in the forecast of a heavy snowfall process during the 2022 Beijing Winter Olympics Games, and proved that the statistical results of the above characteristics can play a role in the forecast of precipitation over complex terrain of Haituo Mountain in winter.
In this study, based on precipitation observation data and ERA5 reanalysis data of Haituo Mountain from 1 January to 15 March of 2019-2021, the 34 winter precipitation processes in Haituo Mountain were classified. The characteristics of observed precipitation at different altitudes under different weather types were analyzed statistically. The results were as follows. According to the influence of weather system and terrain, the winter precipitation in Haituo Mountain can be divided into four weather types: northerly airflow type, easterly airflow type, low eddy trough type, and backflow low eddy trough type. Under different weather types, the direction and intensity of the airflow, the vertical distribution of water vapor and other conditions below the topographic height of Haituo Mountain as well as the interaction with the topographic conditions, make significant differences in precipitation and its duration between different altitudes. The northerly airflow type is controlled by the strong northerly airflow in the whole layer behind the 500 hPa trough, forming the airflow passing over mountain, and the precipitation is concentrated in the high-altitude area. The easterly airflow type is affected by the easterly airflow at the lower level, and the precipitation is concentrated in the low-altitude area. The above two weather types have no synoptic-scale system to accompany, and are dominated by topographic forcing, so the precipitation is small in amount, lasting for relatively short time. The low eddy trough type is affected by the high-altitude eastward movement of low trough, accompanied by the low level southwest airflow, which makes more precipitation at high-altitude area, and this type is also the most frequent weather type in Haituo Mountain in winter. Backflow low eddy trough type is affected by the low trough, with easterly backflow before precipitation to humidify the lower level and play a role of cold cushion, so the precipitation in low-altitude area is more. The above two weather types have synoptic-scale systems, superimposed by the topographic effect of Haituo Mountain terrain, which causes significant precipitation and its long duration, affecting the game run. The above results have been applied in the forecast of a heavy snowfall process during the 2022 Beijing Winter Olympics Games, and proved that the statistical results of the above characteristics can play a role in the forecast of precipitation over complex terrain of Haituo Mountain in winter.
2024, 50(3):331-343.
DOI: 10.7519/j.issn.1000-0526.2023.043001
Abstract:
Tropical cyclone (TC), one of the worst natural disasters in China, has garnered a lot of interests for both its activity characteristics and disaster loss assessment, especially in the context of global warming. In this paper, the combined weighting and k-means clustering methods are used to analyze the spatial and temporal characteristics of TC and its disaster loss in China since 2000. In addition, the disaster grade assessment model of TC based on machine learning algorithm is also constructed. The results show that the frequency of TC landing in China is in a trend of decreasing year by year, but the maximum landing wind speed has been slowly strengthening. Guangdong, Zhejiang, Fujian and Guangxi provinces are seriously affected by TC, but overall, the comprehensive disaster index shows a downward trend. Compared with the classic RF, SVM and NB algorithms, LightGBM (Light Gradient Boosting Machine) has the best performance in assessing the TC disaster loss, and the accuracy can reach 0.91. Moreover, the disaster-inducing factor is the most critical factor in the assessment model, followed by the disaster prevention and mitigation, exposure and vulnerability indicators.
Tropical cyclone (TC), one of the worst natural disasters in China, has garnered a lot of interests for both its activity characteristics and disaster loss assessment, especially in the context of global warming. In this paper, the combined weighting and k-means clustering methods are used to analyze the spatial and temporal characteristics of TC and its disaster loss in China since 2000. In addition, the disaster grade assessment model of TC based on machine learning algorithm is also constructed. The results show that the frequency of TC landing in China is in a trend of decreasing year by year, but the maximum landing wind speed has been slowly strengthening. Guangdong, Zhejiang, Fujian and Guangxi provinces are seriously affected by TC, but overall, the comprehensive disaster index shows a downward trend. Compared with the classic RF, SVM and NB algorithms, LightGBM (Light Gradient Boosting Machine) has the best performance in assessing the TC disaster loss, and the accuracy can reach 0.91. Moreover, the disaster-inducing factor is the most critical factor in the assessment model, followed by the disaster prevention and mitigation, exposure and vulnerability indicators.
2024, 50(3):344-356.
DOI: 10.7519/j.issn.1000-0526.2023.101701
Abstract:
Key Laboratory of Meteorological Disaster, Ministry of Education/ International Joint Laboratory on Climate and Environment Change/Collaborative Innovation Center on Forecast and Evaluation of Meteorological Disasters, Nanjing University of Information Science and Technology, Nanjing 210044; CMA Key Laboratory for Climate Prediction Studies, National Climate Centre, Beijing 100081;Southern Marine Science and Engineering Guangdong Laboratory (Zhuhai), Zhuhai 519082;CMA Economic Transformation of Climate Resources Key Laboratory, Chongqing Institute of Meteorological Sciences, Chongqing 401147 concerned. However, there are few studies on the relationship and mechanism between the Antarctic Oscillation (AAO) and temperature in summer over the TP. Based on observation and reanalysis data such as CRU monthly temperature, NOAA global monthly sea surface temperature data (ERSSTv5), and AAO index from 1979 to 2020, this paper shows that there is a significant negative correlation between the temperature over the western TP in summer and the AAO in May through linear regression analysis and other methods. That is, when the AAO anomaly is positive in May, the temperature over the western TP in summer is abnormally high. The process of its influence is that when the AAO is in a positive phase, a “negative-positive-negative” meridional “Tripole” sea surface temperature mode appears in the mid to high latitudes of the southern Indian Ocean. This mode can last until summer, inducing the wind anomaly over the Indian Ocean in the zonal and vertical direction. The precipitation anomaly between the tropical western Indian Ocean and the eastern Indian Ocean-Maritime Continent leads to a tropical “Dipole” rainfall mode. As a response, abnormal anticyclone circulation and downward movement appear over the western TP, which is conducive to the high temperature there. The research results in this paper indicate that the thermal inertia of the ocean plays an important role as a bridge in the process of prolonging the influence of the AAO, and it can provide scientific basis for the prediction of summer temperature over the TP.
Key Laboratory of Meteorological Disaster, Ministry of Education/ International Joint Laboratory on Climate and Environment Change/Collaborative Innovation Center on Forecast and Evaluation of Meteorological Disasters, Nanjing University of Information Science and Technology, Nanjing 210044; CMA Key Laboratory for Climate Prediction Studies, National Climate Centre, Beijing 100081;Southern Marine Science and Engineering Guangdong Laboratory (Zhuhai), Zhuhai 519082;CMA Economic Transformation of Climate Resources Key Laboratory, Chongqing Institute of Meteorological Sciences, Chongqing 401147 concerned. However, there are few studies on the relationship and mechanism between the Antarctic Oscillation (AAO) and temperature in summer over the TP. Based on observation and reanalysis data such as CRU monthly temperature, NOAA global monthly sea surface temperature data (ERSSTv5), and AAO index from 1979 to 2020, this paper shows that there is a significant negative correlation between the temperature over the western TP in summer and the AAO in May through linear regression analysis and other methods. That is, when the AAO anomaly is positive in May, the temperature over the western TP in summer is abnormally high. The process of its influence is that when the AAO is in a positive phase, a “negative-positive-negative” meridional “Tripole” sea surface temperature mode appears in the mid to high latitudes of the southern Indian Ocean. This mode can last until summer, inducing the wind anomaly over the Indian Ocean in the zonal and vertical direction. The precipitation anomaly between the tropical western Indian Ocean and the eastern Indian Ocean-Maritime Continent leads to a tropical “Dipole” rainfall mode. As a response, abnormal anticyclone circulation and downward movement appear over the western TP, which is conducive to the high temperature there. The research results in this paper indicate that the thermal inertia of the ocean plays an important role as a bridge in the process of prolonging the influence of the AAO, and it can provide scientific basis for the prediction of summer temperature over the TP.
2024, 50(3):357-369.
DOI: 10.7519/j.issn.1000-0526.2023.050301
Abstract:
By using the prediction products of the Beijing Climate Centre Second-Generation Climate Prediction Model System (BCC-CPSv2) and a hybrid downscaling method as well as the Indian Ocean SST signals, this paper establishes a summer precipitation prediction model for eastern part of Northwest China. Relative to BCC-CPSv2 model, the prediction skill of this model is significantly improved for the summer precipitation in eastern part of Northwest China from 1991 to 2017. The spatial correlation coefficient increases from 0.42 to 0.75, and the root mean square error decreases obviously, down most by 80%. The model has better prediction ability for the spatial distribution pattern of precipitation anomaly percentage, such as for the distributions of the summer precipitation anomaly percentages in 1987 and 2010. By grasping the spatial distribution characteristics of meteorological variables, this prediction method can correct the prediction errors of dynamic model products and provide scientific basis and technical support for summer precipitation prediction in eastern part of Northwest China, so it is expected to have a good application prospect.
By using the prediction products of the Beijing Climate Centre Second-Generation Climate Prediction Model System (BCC-CPSv2) and a hybrid downscaling method as well as the Indian Ocean SST signals, this paper establishes a summer precipitation prediction model for eastern part of Northwest China. Relative to BCC-CPSv2 model, the prediction skill of this model is significantly improved for the summer precipitation in eastern part of Northwest China from 1991 to 2017. The spatial correlation coefficient increases from 0.42 to 0.75, and the root mean square error decreases obviously, down most by 80%. The model has better prediction ability for the spatial distribution pattern of precipitation anomaly percentage, such as for the distributions of the summer precipitation anomaly percentages in 1987 and 2010. By grasping the spatial distribution characteristics of meteorological variables, this prediction method can correct the prediction errors of dynamic model products and provide scientific basis and technical support for summer precipitation prediction in eastern part of Northwest China, so it is expected to have a good application prospect.
2024, 50(3):370-376.
DOI: 10.7519/j.issn.1000-0526.2024.022101
Abstract:
In 2023, the global mean temperature was about 1.45℃(±0.12℃) above pre-industrial level, making it the warmest year on record. Global sea level continued to rise, and the global mean sea levels reached the highest level since satellite records began from 1993, reflecting the persistent ocean warming and the melting glaciers and ice sheets. The Arctic sea ice extent remained well below normal values, and the Antarctic sea ice extent hit a record low. Pakistan, Beijing-Tianjin-Hebei Region of China, Italy, northern coastal areas of Sao Paulo State of Brazil, North Island of New Zealand and other places suffered from torrential rains and floods. Severe droughts occurred in north-western Africa, Yunnan Province of China, central American and northern South America. Record-breaking heat waves hit southern Europe, North America, South America, East Asia and South Asia. Europe and North America experienced cold snaps and blizzards. Severe convective weather frequently stroke here and there on the globe, and tropical cyclones were frequently active around the world.
In 2023, the global mean temperature was about 1.45℃(±0.12℃) above pre-industrial level, making it the warmest year on record. Global sea level continued to rise, and the global mean sea levels reached the highest level since satellite records began from 1993, reflecting the persistent ocean warming and the melting glaciers and ice sheets. The Arctic sea ice extent remained well below normal values, and the Antarctic sea ice extent hit a record low. Pakistan, Beijing-Tianjin-Hebei Region of China, Italy, northern coastal areas of Sao Paulo State of Brazil, North Island of New Zealand and other places suffered from torrential rains and floods. Severe droughts occurred in north-western Africa, Yunnan Province of China, central American and northern South America. Record-breaking heat waves hit southern Europe, North America, South America, East Asia and South Asia. Europe and North America experienced cold snaps and blizzards. Severe convective weather frequently stroke here and there on the globe, and tropical cyclones were frequently active around the world.
2024, 50(3):377-386.
DOI: 10.7519/j.issn.1000-0526.2024.013001
Abstract:
In the summer of 2023, China experienced a climate of higher temperature and less precipitation. Both the droughts and the floods showed remarkable spatial differences. Although the numbers of typhoons generated and landing in summer were both less than normal, the typhoons that formed were extremely destructive. In terms of temperature, persistent heat waves were the most prominent in North China and Northwest China since 1961, but the intensities of high temperature and drought were significantly weaker than those in the summer of 2022 across the Yangtze River Basin. The prediction effect has shown that the climate prediction successfully forecasted the characteristics of the rain belt in northern China, and made accurate prediction and early warning of the possible heavy floods in Songhua River Basin, Nenjiang River Basin and Haihe River Basin. The forecasted number, main track and affected area of tropical cyclones in summer were also consistent with the observation. Prediction skills of mean temperatures in most parts of China are higher than normal, especially the heat wave intensity in the Yangtze River Basin in 2023. The primary error of precipitation forecast in the rainy season mainly occurred in South China, and the extreme high temperature processes were underestimated for North China and Huanghuai Region. In addition, the precursors and their forecasting performance in summer 2023 are also reviewed and diagnosed. The results indicate that both the interdecadal and interannual variations of external forcing had good indicative significances for the prediction of rain belt in northern China. However, almost all the precursors gave consistent wrong information about the precipitation in South China, which was the main reason for the failure of precipitation forecast in South China.
In the summer of 2023, China experienced a climate of higher temperature and less precipitation. Both the droughts and the floods showed remarkable spatial differences. Although the numbers of typhoons generated and landing in summer were both less than normal, the typhoons that formed were extremely destructive. In terms of temperature, persistent heat waves were the most prominent in North China and Northwest China since 1961, but the intensities of high temperature and drought were significantly weaker than those in the summer of 2022 across the Yangtze River Basin. The prediction effect has shown that the climate prediction successfully forecasted the characteristics of the rain belt in northern China, and made accurate prediction and early warning of the possible heavy floods in Songhua River Basin, Nenjiang River Basin and Haihe River Basin. The forecasted number, main track and affected area of tropical cyclones in summer were also consistent with the observation. Prediction skills of mean temperatures in most parts of China are higher than normal, especially the heat wave intensity in the Yangtze River Basin in 2023. The primary error of precipitation forecast in the rainy season mainly occurred in South China, and the extreme high temperature processes were underestimated for North China and Huanghuai Region. In addition, the precursors and their forecasting performance in summer 2023 are also reviewed and diagnosed. The results indicate that both the interdecadal and interannual variations of external forcing had good indicative significances for the prediction of rain belt in northern China. However, almost all the precursors gave consistent wrong information about the precipitation in South China, which was the main reason for the failure of precipitation forecast in South China.
2024, 50(3):387-392.
DOI: 10.7519/j.issn.1000-0526.2024.022601
Abstract:
The main characteristics of the general atmospheric circulation in December 2023 are as follows. There were several polar vortex centers in the Northern Hemisphere. The atmospheric circulation presented a great meridionality in mid-latitudes in Eurasia. The East Asian trough was stronger, and the subtropical high ridge in the Western Pacific Ocean was also abnormally stronger this month. The monthly mean precipitation (12.2 mm) over China was 2.5% more than normal (11.9 mm), and the monthly average temperature was -2.6℃, which is 0.4℃ above that in the same period of normal years. Totally, there were six cold air processes, one sand-dust weather process and one large-scale fog-haze event reported this month. In particular, the 13-16 December intense cold wave that was encountered in most parts of China heavily was featured with wide influence range, large cooling range and remarkable low temperature extremes.
The main characteristics of the general atmospheric circulation in December 2023 are as follows. There were several polar vortex centers in the Northern Hemisphere. The atmospheric circulation presented a great meridionality in mid-latitudes in Eurasia. The East Asian trough was stronger, and the subtropical high ridge in the Western Pacific Ocean was also abnormally stronger this month. The monthly mean precipitation (12.2 mm) over China was 2.5% more than normal (11.9 mm), and the monthly average temperature was -2.6℃, which is 0.4℃ above that in the same period of normal years. Totally, there were six cold air processes, one sand-dust weather process and one large-scale fog-haze event reported this month. In particular, the 13-16 December intense cold wave that was encountered in most parts of China heavily was featured with wide influence range, large cooling range and remarkable low temperature extremes.
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ISSN:1000-0526 CN:11-2282/P