ISSN 1000-0526
CN 11-2282/P
CN 11-2282/P
Volume 51,Issue 3,2025 Table of Contents
CHAO Qingchen
,
QIU Zongxu
,
FENG Aiqing
,
HAN Zhenyu
,
YANG Honglong
,
HAN Qinmei
,
LIU Yuan
,
WANG Qiuling
,
QIN Yun
,
WANG Yang
2025, 51(3):257-268.
DOI: 10.7519/j.issn.1000-0526.2024.122201
Abstract:
Under the global climate change, climate risks in cities have become a focal point of academic research and policy-making. This study analyzes the historical climate evolution, future trends, and risks in key domains by the case study on Shenzhen City. The findings indicate that Shenzhen has experienced rapid rise in temperature, significant interannual variability in precipitation, and a general decline in wind speed from 1953 to 2023. The extreme changes of major meteorological disasters such as high temperature, extreme precipitation and typhoons are obvious, and will be further intensified in the future. Thus, urban climate risks are projected to become more complex. Climate change is very likely to affect ecosystem, water resources, human health, energy load and infrastructure in Shenzhen, and that would be more negative than positive impact overall. Droughts and floods will significantly affect vegetation growth. The runoff in the western Pearl River Basin will decrease and exacerbate water resource management challenges. Heatwaves is in all likelihood to pose substantial health risks, particularly in the densely-populated western urban areas. Rising temperature and humidity levels can drive up residential electricity demands, and increase the pressure on the energy supply system. Meanwhile, the city’s drainage system will face much greater flood risks as extreme precipitation events test the resilience of urban infrastructure. Additionally, the cascading effects of extreme climate events across multiple systems may amplify socio-economic losses. To effectively mitigate extreme climate events and reduce the adverse impacts of climate change in the future, early warning systems are recognized as a critical adaptation measure. Shenzhen has developed a relatively advanced response framework, significantly enhancing meteorological monitoring, risk assessment, and emergency response capabilities. The climate risk assessment of Shenzhen and its response model are of great significance to the response to climate change in megacities in China. Therefore, strengthening the nationwide climate risk assessment, institutionalizing disaster surveys and hazard identification, and improving cross-sectoral collaboration in early warning systems are recommended to comprehensively enhance the climate resilience of cities.
Under the global climate change, climate risks in cities have become a focal point of academic research and policy-making. This study analyzes the historical climate evolution, future trends, and risks in key domains by the case study on Shenzhen City. The findings indicate that Shenzhen has experienced rapid rise in temperature, significant interannual variability in precipitation, and a general decline in wind speed from 1953 to 2023. The extreme changes of major meteorological disasters such as high temperature, extreme precipitation and typhoons are obvious, and will be further intensified in the future. Thus, urban climate risks are projected to become more complex. Climate change is very likely to affect ecosystem, water resources, human health, energy load and infrastructure in Shenzhen, and that would be more negative than positive impact overall. Droughts and floods will significantly affect vegetation growth. The runoff in the western Pearl River Basin will decrease and exacerbate water resource management challenges. Heatwaves is in all likelihood to pose substantial health risks, particularly in the densely-populated western urban areas. Rising temperature and humidity levels can drive up residential electricity demands, and increase the pressure on the energy supply system. Meanwhile, the city’s drainage system will face much greater flood risks as extreme precipitation events test the resilience of urban infrastructure. Additionally, the cascading effects of extreme climate events across multiple systems may amplify socio-economic losses. To effectively mitigate extreme climate events and reduce the adverse impacts of climate change in the future, early warning systems are recognized as a critical adaptation measure. Shenzhen has developed a relatively advanced response framework, significantly enhancing meteorological monitoring, risk assessment, and emergency response capabilities. The climate risk assessment of Shenzhen and its response model are of great significance to the response to climate change in megacities in China. Therefore, strengthening the nationwide climate risk assessment, institutionalizing disaster surveys and hazard identification, and improving cross-sectoral collaboration in early warning systems are recommended to comprehensively enhance the climate resilience of cities.
2025, 51(3):269-284.
DOI: 10.7519/j.issn.1000-0526.2025.011601
Abstract:
Two persistent extreme rainstorms occurred in Sichuan Basin during 10-13 and 14-18 August 2020 resulting in secondary disasters， casualties， and huge economic losses.To deeply understand the development mechanism of extreme rainstorms and the disaster-causing mechanism, using various observations and ERA5 reanalysis data, we comparatively analyze the precipitation characteristics of these two rainstorms, and the development, evolution and trigger mechanism of mesoscale convective systems (MCSs) in the heaviest precipitation stage. The results show that the two rainstorm processes both occurred under the circulation background with “two troughs and one ridge” in the middle and high latitudes. They were typical rainstorms accompanied by “east-high-pressure and west-low-pressure” in the basin， and brought precipitation over 250 mm·d-1 (or 100 mm·h-1). The hourly rainfall of the 10-13 August rainstorm exceeded the historical extremes，while that of the 14-18 August rainstorm was equivalent to the historical statistical value. The most intense precipitation stage of the 10-13 August rainstorm was a warm-sector rainstorm， which was caused by a mesoscale convective complex occurrence-development-maturation-weakening process. The radar echo areas ≥40 dBz in this rainstorm were wide and long-lasting. And the echo centroid was low and the intensity was more than 55 dBz. The heaviest precipitation phase of the 14-18 August rainstorm was a mixed precipitation induced by a two α-MCS occurrence-development-merger-weakening process. The radar echo areas ≥40 dBz were narrow and short-lived. The echo centroid was low and the intensity reached 50 dBz. Convection in the 10-13 August rainstorm was produced by horn-mouth terrain flow， windward slop uplift and high temperature gradient zone， and was sustained with strong warm advection at low level， weak cold advection at high level at the same time. The 14-18 August rainstorm convection was triggered by the convergence of the lower troposphere cold， warm currents and the left convergence of the low-altitude jet stream in the warm zone. The shear formed by the intersection of the cold and warm currents led to the persistence of the precipitation.
Two persistent extreme rainstorms occurred in Sichuan Basin during 10-13 and 14-18 August 2020 resulting in secondary disasters， casualties， and huge economic losses.To deeply understand the development mechanism of extreme rainstorms and the disaster-causing mechanism, using various observations and ERA5 reanalysis data, we comparatively analyze the precipitation characteristics of these two rainstorms, and the development, evolution and trigger mechanism of mesoscale convective systems (MCSs) in the heaviest precipitation stage. The results show that the two rainstorm processes both occurred under the circulation background with “two troughs and one ridge” in the middle and high latitudes. They were typical rainstorms accompanied by “east-high-pressure and west-low-pressure” in the basin， and brought precipitation over 250 mm·d-1 (or 100 mm·h-1). The hourly rainfall of the 10-13 August rainstorm exceeded the historical extremes，while that of the 14-18 August rainstorm was equivalent to the historical statistical value. The most intense precipitation stage of the 10-13 August rainstorm was a warm-sector rainstorm， which was caused by a mesoscale convective complex occurrence-development-maturation-weakening process. The radar echo areas ≥40 dBz in this rainstorm were wide and long-lasting. And the echo centroid was low and the intensity was more than 55 dBz. The heaviest precipitation phase of the 14-18 August rainstorm was a mixed precipitation induced by a two α-MCS occurrence-development-merger-weakening process. The radar echo areas ≥40 dBz were narrow and short-lived. The echo centroid was low and the intensity reached 50 dBz. Convection in the 10-13 August rainstorm was produced by horn-mouth terrain flow， windward slop uplift and high temperature gradient zone， and was sustained with strong warm advection at low level， weak cold advection at high level at the same time. The 14-18 August rainstorm convection was triggered by the convergence of the lower troposphere cold， warm currents and the left convergence of the low-altitude jet stream in the warm zone. The shear formed by the intersection of the cold and warm currents led to the persistence of the precipitation.
2025, 51(3):285-297.
DOI: 10.7519/j.issn.1000-0526.2024.121201
Abstract:
Backward tracking and quantitative analysis of water vapor transport at different altitudes during rainstorms on the eastern, western, and east-west feet of Helan Mountains from 2001 to 2019 are conducted by the Hybrid Single Particle Lagrangian Integrated Trajectory Model (HYSPLIT), based on hourly precipitation observations and GDAS reanalysis data with a spatial resolution of 1.0°×1.0° and a temporal resolution of 6 hours. It is found that significant differences exist in water vapor transport patterns at different altitudes during rainstorms across different regions of Helan Mountains. At the eastern foot, the southerly path is identified as the primary transport route below 3000 m, with a water vapor contribution rate of 57.3% to 75.2%. The contribution of the westerly path is observed to increase with altitude, reaching 100% at the 5000 m height. At the western foot, the westerly path is found to be the dominant transport route, with a water vapor contribution rate ranging from 31.8% to 67.5%. The southerly path is the secondary, with the contribution rate ranging from 23.8% to 68.2%, while the northerly path appears only at the heights of 100 m and 1000 m, contributing 28.9% to 39.4%. In the east-west foot region, the westerly path is determined to contribute 100% of the water vapor at all altitudes. The Eurasian westerlies are identified as the predominant source of water vapor, particularly during rainstorms in the east-west foot region, where the water vapor contribution is the highest at all altitudes except at the 1000 m height. Secondary water vapor sources include the Qinghai and Gansu regions, the middle and lower reaches of Yangtze River, and the waters of the Black Sea, Caspian Sea, Lake Balkhash, and Lake Baikal, which are found to supply moisture to rainstorms at the east-west, eastern, and western feet, respectively. The Hengduan Mountains are identified as contributing moisture at isolated altitudes during rainstorms at the eastern and western feet, and its contribution was minimal.
Backward tracking and quantitative analysis of water vapor transport at different altitudes during rainstorms on the eastern, western, and east-west feet of Helan Mountains from 2001 to 2019 are conducted by the Hybrid Single Particle Lagrangian Integrated Trajectory Model (HYSPLIT), based on hourly precipitation observations and GDAS reanalysis data with a spatial resolution of 1.0°×1.0° and a temporal resolution of 6 hours. It is found that significant differences exist in water vapor transport patterns at different altitudes during rainstorms across different regions of Helan Mountains. At the eastern foot, the southerly path is identified as the primary transport route below 3000 m, with a water vapor contribution rate of 57.3% to 75.2%. The contribution of the westerly path is observed to increase with altitude, reaching 100% at the 5000 m height. At the western foot, the westerly path is found to be the dominant transport route, with a water vapor contribution rate ranging from 31.8% to 67.5%. The southerly path is the secondary, with the contribution rate ranging from 23.8% to 68.2%, while the northerly path appears only at the heights of 100 m and 1000 m, contributing 28.9% to 39.4%. In the east-west foot region, the westerly path is determined to contribute 100% of the water vapor at all altitudes. The Eurasian westerlies are identified as the predominant source of water vapor, particularly during rainstorms in the east-west foot region, where the water vapor contribution is the highest at all altitudes except at the 1000 m height. Secondary water vapor sources include the Qinghai and Gansu regions, the middle and lower reaches of Yangtze River, and the waters of the Black Sea, Caspian Sea, Lake Balkhash, and Lake Baikal, which are found to supply moisture to rainstorms at the east-west, eastern, and western feet, respectively. The Hengduan Mountains are identified as contributing moisture at isolated altitudes during rainstorms at the eastern and western feet, and its contribution was minimal.
2025, 51(3):298-312.
DOI: 10.7519/j.issn.1000-0526.2024.121901
Abstract:
Eight different cloud microphysical schemes in the WRF model are used to simulate the precipitation process caused by a squall line in Hainan Island on 22 April 2020, and the effects of different cloud microphysical schemes on the simulation of the Hainan Island squall line are comparatively analyzed. The results show that different cloud microphysical schemes have significant differences in simulating the surface precipitation, radar composite reflectivity, thermodynamic and dynamic fields. Among them, the precipitation area and center intensity simulated by Thompson scheme are most close to the actual observations, and the radar composite reflectivity in intensity, range and pattern simulated by WSM6 scheme at the time of heaviest precipitation is similar to the actual observations. In the thermodynamic and dynamic fields, the characteristics of squall line such as surface cold pool, low-level vertical wind shear and cold pool outflow can be simulated by all schemes, and the precipitation center corresponds to the strong updraft zone. The divergence structure of low-level convergence and high-level divergence is conducive to the occurrence of severe convection and the formation of precipitation, but there exist differences in the intensity and distribution of precipitation. According to the cloud microphysical characteristics, the liquid-phase particles are mainly distributed below 5 km, and the ice-phase particales are above 6 km. The simulation results of cloud water show the weakest response to the selection of cloud microphysical schemes, while the distributions of snow and graupel show the high sensitivity. This is because different cloud microphysical schemes have different processing ways for the generation, transformation and consumption of snow and graupel, and the conversion rate of the same microphysical process is also different in different schemes.
Eight different cloud microphysical schemes in the WRF model are used to simulate the precipitation process caused by a squall line in Hainan Island on 22 April 2020, and the effects of different cloud microphysical schemes on the simulation of the Hainan Island squall line are comparatively analyzed. The results show that different cloud microphysical schemes have significant differences in simulating the surface precipitation, radar composite reflectivity, thermodynamic and dynamic fields. Among them, the precipitation area and center intensity simulated by Thompson scheme are most close to the actual observations, and the radar composite reflectivity in intensity, range and pattern simulated by WSM6 scheme at the time of heaviest precipitation is similar to the actual observations. In the thermodynamic and dynamic fields, the characteristics of squall line such as surface cold pool, low-level vertical wind shear and cold pool outflow can be simulated by all schemes, and the precipitation center corresponds to the strong updraft zone. The divergence structure of low-level convergence and high-level divergence is conducive to the occurrence of severe convection and the formation of precipitation, but there exist differences in the intensity and distribution of precipitation. According to the cloud microphysical characteristics, the liquid-phase particles are mainly distributed below 5 km, and the ice-phase particales are above 6 km. The simulation results of cloud water show the weakest response to the selection of cloud microphysical schemes, while the distributions of snow and graupel show the high sensitivity. This is because different cloud microphysical schemes have different processing ways for the generation, transformation and consumption of snow and graupel, and the conversion rate of the same microphysical process is also different in different schemes.
2025, 51(3):313-323.
DOI: 10.7519/j.issn.1000-0526.2024.031405
Abstract:
Based on the observation data of Henan Province during the winter half of the year from 1991 to 2020, the low temperature threshold, the process and duration of cryogenic freezing rain and snow are determined by mathematical statistics, and the meteorological indexes of each station are calculated and classified. The classification results are then subjected to spatio-temporal characteristic statistics and analysis of typical cases. The results show that the mountainous area of western Henan is a high incidence area of cryogenic freezing rain and snow, while the basins of southwestern Henan and northwestern Henan are the low incidence areas. The multi-year average frequency of the cryogenic freezing rain and snow at all sites is in descending trend from light to the heavy grade. The frequency and grade of cryogenic freezing rain and snow are not positively correlated with the latitude level, and extra-heavy events occur even more frequently at low-latitude sites than at high-latitude and mountain sites. In 2001, the number of cryogenic freezing rain and snow sites and frequencies was the most and the intensity was high, while in 2007, the number was the least and the intensity was mild. In 2018, the cryogenic freezing rain and snow was serious. January is the month to have the highest number of cryogenic freezing rain and snow sites and frequencies, followed by February. Temperature and precipitation are the key factors for the cryogenic freezing rain and snow. Low temperature and heavy precipitation are favorable for the occurrence of freezing weather. Temperature is the main factor affecting the frozen grade in the high altitude area while accumulated precipitation is the primary factor determining the frozen grade in the plain area. In addition, the location, intensity and moving speed of the weather system determine the hit area, grade and duration of cryogenic freezing rain and snow.
Based on the observation data of Henan Province during the winter half of the year from 1991 to 2020, the low temperature threshold, the process and duration of cryogenic freezing rain and snow are determined by mathematical statistics, and the meteorological indexes of each station are calculated and classified. The classification results are then subjected to spatio-temporal characteristic statistics and analysis of typical cases. The results show that the mountainous area of western Henan is a high incidence area of cryogenic freezing rain and snow, while the basins of southwestern Henan and northwestern Henan are the low incidence areas. The multi-year average frequency of the cryogenic freezing rain and snow at all sites is in descending trend from light to the heavy grade. The frequency and grade of cryogenic freezing rain and snow are not positively correlated with the latitude level, and extra-heavy events occur even more frequently at low-latitude sites than at high-latitude and mountain sites. In 2001, the number of cryogenic freezing rain and snow sites and frequencies was the most and the intensity was high, while in 2007, the number was the least and the intensity was mild. In 2018, the cryogenic freezing rain and snow was serious. January is the month to have the highest number of cryogenic freezing rain and snow sites and frequencies, followed by February. Temperature and precipitation are the key factors for the cryogenic freezing rain and snow. Low temperature and heavy precipitation are favorable for the occurrence of freezing weather. Temperature is the main factor affecting the frozen grade in the high altitude area while accumulated precipitation is the primary factor determining the frozen grade in the plain area. In addition, the location, intensity and moving speed of the weather system determine the hit area, grade and duration of cryogenic freezing rain and snow.
2025, 51(3):324-336.
DOI: 10.7519/j.issn.1000-0526.2024.120902
Abstract:
Based on the 2019-2023 grid rainfall observation and multi-model forecasts in Zhejiang Province during the flood season from May to October, the accuracy of the areal rainfall forecasts for 32 large-sized reservoirs within the basin of Zhejiang Province by multi-model objective consensus forecasting (OCF) is evaluated by means of various indicators and methods, and the results are further compared with those of the model of European Centre for Medium-Range Weather Forecasts (EC model). The results demonstrate that the forecast accuracy of areal rainfall by OCF model is related to the catchment area of reservoir, the location of reservoir and the synoptic processes bringing precipitation. On the whole, the forecast accuracy of areal rainfall by OCF model for Type Ⅰ large-sized reservoirs is higher than that for Type Ⅱ. The forecast error of OCF model mainly comes from the missing alarm. By reducing the missing alarm rate, the forecast accuracy of areal rainfall by OCF model for Type Ⅱ large-sized reservoirs located in eastern part of the Central Zhejiang can be significantly improved. Especially for the areal rainfall over 15 mm, it has obvious advantages compared to EC model. Although the forecasting accuracy of OCF model decreases gradually with the extension of forecast lead time, it has better effect than EC model in forecasting the areal rainfall over 6 mm. For different heavy precipitation processes in Zhejiang Province, OCF model has higher forecasting ability and better performance than EC model for the reservoir basins that are mainly affected by Meiyu (typhoon) during Meiyu period (typhoon period). The forecasting accuracy of OCF model improves with the approach of forecast lead time during both Meiyu and typhoon periods. However, owing to the influence of the forecasting accuracy of typhoon tracks, the latter fluctuates dramatically and has obvious advantages relative to EC model in most forecast lead time of 24-120 h. The above results could provide some necessary reference for the hydrometeorological service.
Based on the 2019-2023 grid rainfall observation and multi-model forecasts in Zhejiang Province during the flood season from May to October, the accuracy of the areal rainfall forecasts for 32 large-sized reservoirs within the basin of Zhejiang Province by multi-model objective consensus forecasting (OCF) is evaluated by means of various indicators and methods, and the results are further compared with those of the model of European Centre for Medium-Range Weather Forecasts (EC model). The results demonstrate that the forecast accuracy of areal rainfall by OCF model is related to the catchment area of reservoir, the location of reservoir and the synoptic processes bringing precipitation. On the whole, the forecast accuracy of areal rainfall by OCF model for Type Ⅰ large-sized reservoirs is higher than that for Type Ⅱ. The forecast error of OCF model mainly comes from the missing alarm. By reducing the missing alarm rate, the forecast accuracy of areal rainfall by OCF model for Type Ⅱ large-sized reservoirs located in eastern part of the Central Zhejiang can be significantly improved. Especially for the areal rainfall over 15 mm, it has obvious advantages compared to EC model. Although the forecasting accuracy of OCF model decreases gradually with the extension of forecast lead time, it has better effect than EC model in forecasting the areal rainfall over 6 mm. For different heavy precipitation processes in Zhejiang Province, OCF model has higher forecasting ability and better performance than EC model for the reservoir basins that are mainly affected by Meiyu (typhoon) during Meiyu period (typhoon period). The forecasting accuracy of OCF model improves with the approach of forecast lead time during both Meiyu and typhoon periods. However, owing to the influence of the forecasting accuracy of typhoon tracks, the latter fluctuates dramatically and has obvious advantages relative to EC model in most forecast lead time of 24-120 h. The above results could provide some necessary reference for the hydrometeorological service.
7 Characteristics of FY-4A Satellite Cloud Physical Parameters in Severe Convective Weather in Ningxia
2025, 51(3):337-348.
DOI: 10.7519/j.issn.1000-0526.2025.011602
Abstract:
Based on the observation data of FY-4A Advanced Geosynchronous Radiation Imager (AGRI) and surface observation data during 2018-2020, the distribution characteristics of satellite products in different severe convective weathers, including short-time heavy precipitation, lightning and hail, are studied by using statistical methods such as normal distribution test and correlation analysis. The results are as follows. The difference of convection in severe convective weather leads to different distribution characteristics of FY-4A satellite products. During short-time heavy precipitation, the cloud top temperature (CTT) and black body temperature (TBB) are mainly concentrated in the range of 200-280 K, and different cloud shapes lead to significant differences in temperature ranges. However, during lightning and hail processes, the main ranges of CTT and TBB are located between 210-270 K. More than 50% of short-time heavy precipitation, 75% of lightning, and more than 90% of hail occur at altitudes above 5000 m (500 hPa). The radii of cloud droplets in different convective weathers are obviously different. Short-time heavy precipitation, lightning and hail correspond to small, middle and large cloud droplets, respectively. When the liquid water content (LWC) in clouds exceeds 500 g·m-2, short-time heavy precipitation is prone to occur. For lightning, the LWC ranges from 250 to 400 g·m-2, and for hail, it ranges from 400 to 600 g·m-2. Moderate intensity tropopause folding depth (TZD) is conducive to the occurrence and maintenance of heavy precipitation and lightning, while hail requires deeper folding depth. Except that the CTT and the cloud top height (CTH) in the lightning hail series show normal distribution or quasi-normal distribution characteristics, other FY-4A products do not conform to normal distribution. FY-4A products are significantly correlated to short-time heavy precipitation in CTT, TBB, LWC and TZD, lightning in CTT, TBB and TZD, as well as hail in CTT, CTH, TBB, LWC and TZD. These products need to be paid more attention to in monitoring and early warning operations.
Based on the observation data of FY-4A Advanced Geosynchronous Radiation Imager (AGRI) and surface observation data during 2018-2020, the distribution characteristics of satellite products in different severe convective weathers, including short-time heavy precipitation, lightning and hail, are studied by using statistical methods such as normal distribution test and correlation analysis. The results are as follows. The difference of convection in severe convective weather leads to different distribution characteristics of FY-4A satellite products. During short-time heavy precipitation, the cloud top temperature (CTT) and black body temperature (TBB) are mainly concentrated in the range of 200-280 K, and different cloud shapes lead to significant differences in temperature ranges. However, during lightning and hail processes, the main ranges of CTT and TBB are located between 210-270 K. More than 50% of short-time heavy precipitation, 75% of lightning, and more than 90% of hail occur at altitudes above 5000 m (500 hPa). The radii of cloud droplets in different convective weathers are obviously different. Short-time heavy precipitation, lightning and hail correspond to small, middle and large cloud droplets, respectively. When the liquid water content (LWC) in clouds exceeds 500 g·m-2, short-time heavy precipitation is prone to occur. For lightning, the LWC ranges from 250 to 400 g·m-2, and for hail, it ranges from 400 to 600 g·m-2. Moderate intensity tropopause folding depth (TZD) is conducive to the occurrence and maintenance of heavy precipitation and lightning, while hail requires deeper folding depth. Except that the CTT and the cloud top height (CTH) in the lightning hail series show normal distribution or quasi-normal distribution characteristics, other FY-4A products do not conform to normal distribution. FY-4A products are significantly correlated to short-time heavy precipitation in CTT, TBB, LWC and TZD, lightning in CTT, TBB and TZD, as well as hail in CTT, CTH, TBB, LWC and TZD. These products need to be paid more attention to in monitoring and early warning operations.
ZHAO LinZhuozhuo
,
ZHANG Daquan
,
JIANG Yundi
,
ZHONG Hailing
,
LI Xiang
,
CHEN Xianyan
,
LI Xiucang
,
ZOU Xukai
,
WANG Yiran
,
ZENG Hongling
,
CUI Tong
,
YIN Yizhou
,
WANG Youmin
,
ZHOU Xingyan
,
ZHU Xiaojin
,
DAI Tanlong
,
QIAO Qi
,
CHEN Yixiao
,
LYU Zhuozhuo
,
ZHANG Daquan
2025, 51(3):349-357.
DOI: 10.7519/j.issn.1000-0526.2025.022401
Abstract:
China underwent a warmer and wetter climate in 2024. Temperatures kept a higher than normal level in all the four seasons, and the national mean temperature reached a record high in the same period since 1951. Especially, spring, summer and autumn were the warmest relative to that in the same period since 1961. The national average precipitation was the fourth most in the same period since 1951, and the precipitation amount in all four seasons was more than the average. There were 70 national meteorological stations in China seeing daily precipitation break the historical extreme values. In 2024, the heaviest rainstorm process since 1961 occurred in southern China. The extremely high temperature came early, with the middle and eastern regions of China plagued by the second hottest weather in the same period since 1961. The autumn typhoons were active and extreme, and Typhoon Capricorn seriously impacted Hainan, Guangdong, Guangxi and other adjacent areas. The drought condition was generally mild but its stages were obvious. The winter and spring drought occurred in Southwest China. The cold air processes were more than usual, the severe convection events occurred frequently, and the influence of sand-dust was at a low level.
China underwent a warmer and wetter climate in 2024. Temperatures kept a higher than normal level in all the four seasons, and the national mean temperature reached a record high in the same period since 1951. Especially, spring, summer and autumn were the warmest relative to that in the same period since 1961. The national average precipitation was the fourth most in the same period since 1951, and the precipitation amount in all four seasons was more than the average. There were 70 national meteorological stations in China seeing daily precipitation break the historical extreme values. In 2024, the heaviest rainstorm process since 1961 occurred in southern China. The extremely high temperature came early, with the middle and eastern regions of China plagued by the second hottest weather in the same period since 1961. The autumn typhoons were active and extreme, and Typhoon Capricorn seriously impacted Hainan, Guangdong, Guangxi and other adjacent areas. The drought condition was generally mild but its stages were obvious. The winter and spring drought occurred in Southwest China. The cold air processes were more than usual, the severe convection events occurred frequently, and the influence of sand-dust was at a low level.
2025, 51(3):358-368.
DOI: 10.7519/j.issn.1000-0526.2025.022501
Abstract:
The main characteristics of climate in the flood season 2024 were accurately predicted by the National Climate Centre, including that the overall climate condition was unfavorable and the flood disasters had more serious impact than drought. The prediction of excessive precipitation in the eastern monsoon region was highly consistent with observations. At the same time, the stage characteristics of flood situation were accurately predicted, that is, the flood situation was serious first in the middle and lower reaches of the Yangtze River, the Huaihe River Basin and the Taihu Lake Basin before mid-July and then in the Songhua River Basin, the Liaohe River Basin and the Haihe River Basin after mid-July. The prediction of “overall high temperature nationwide in summer, multiple high temperature processes in North China, Huanghuai Region and other places in early summer, and multiple high temperature processes in the south of China in mid-summer” was in line with observations. The shortcoming of the flood season prediction was that the impact of typhoons on extreme precipitation in South China under the background of fewer typhoons was underestimated. The predictions of circulation situation from multiple dynamic climate models for the tropical and subtropical regions were in a relatively good agreement with observations. The models’ predictions of large range of excessive precipitation in eastern China and national temperatures higher than normal were basically consistent with observations as well. In addition, this article analyzes and assesses the precursor signals for the flood season 2024 climate prediction from interdecadal and interannual time scales. The sea surface temperature (SST) anomalies in the equatorial eastern and central Pacific, tropical Indian Ocean, and tropical Atlantic during the 2023/2024 winter were all remarkable, while the anomalies of the snow cover and polar ice were relatively weak. Therefore, the study focus is on the impact of the SST distribution in the three oceans on the flood season climate of China. Observations also show that the SST anomalies from the three oceans were conducive to strengthening the western Pacific subtropical high, leading to the widespread excessive precipitation in the eastern monsoon region of China.
The main characteristics of climate in the flood season 2024 were accurately predicted by the National Climate Centre, including that the overall climate condition was unfavorable and the flood disasters had more serious impact than drought. The prediction of excessive precipitation in the eastern monsoon region was highly consistent with observations. At the same time, the stage characteristics of flood situation were accurately predicted, that is, the flood situation was serious first in the middle and lower reaches of the Yangtze River, the Huaihe River Basin and the Taihu Lake Basin before mid-July and then in the Songhua River Basin, the Liaohe River Basin and the Haihe River Basin after mid-July. The prediction of “overall high temperature nationwide in summer, multiple high temperature processes in North China, Huanghuai Region and other places in early summer, and multiple high temperature processes in the south of China in mid-summer” was in line with observations. The shortcoming of the flood season prediction was that the impact of typhoons on extreme precipitation in South China under the background of fewer typhoons was underestimated. The predictions of circulation situation from multiple dynamic climate models for the tropical and subtropical regions were in a relatively good agreement with observations. The models’ predictions of large range of excessive precipitation in eastern China and national temperatures higher than normal were basically consistent with observations as well. In addition, this article analyzes and assesses the precursor signals for the flood season 2024 climate prediction from interdecadal and interannual time scales. The sea surface temperature (SST) anomalies in the equatorial eastern and central Pacific, tropical Indian Ocean, and tropical Atlantic during the 2023/2024 winter were all remarkable, while the anomalies of the snow cover and polar ice were relatively weak. Therefore, the study focus is on the impact of the SST distribution in the three oceans on the flood season climate of China. Observations also show that the SST anomalies from the three oceans were conducive to strengthening the western Pacific subtropical high, leading to the widespread excessive precipitation in the eastern monsoon region of China.
2025, 51(3):369-381.
DOI: 10.7519/j.issn.1000-0526.2024.122701
Abstract:
Using the best track data of China Meteorological Administration (CMA) from 1949 to 2023, real-time operational forecast data of typhoon track and intensity in 2023 from National Meteorological Centre (NMC) of CMA, and the ERA5 reanalysis data from the European Centre for Medium-Range Weather Forecasts (ECMWF), we analyze the main characteristics of typhoon activities in the Western North Pacific in 2023. The results show that in 2023, the numbers of generated typhoons and the landfall typhoons were both at a relatively low level, but the extreme intensity of typhoons and landfall intensities were stronger. The generation source areas of typhoons shifted eastward, with fewer typhoons born in the South China Sea and fewer typhoons making landfall in summer. The landfall localities of typhoons were more concentrated, and the landfall typhoons travelled further inland, causing widespread and severe damages. Although the 24 h typhoon track forecast errors by NMC in 2023 reached a historic low point, the track forecast errors within 1-4 d were higher than those of the Japan Meteorological Agency (JMA) and the U.S. Joint Typhoon Warning Center (JTWC). The intensity forecast errors for typhoons within 1-5 d lead time increased compared to last five years’ levels, but still better than JMA and worse than JTWC. The large challenges in typhoon forecasting in 2023 lay in the inland penetration and prolonged duration of Typhoon Doksuri which brought extreme precipitation in North China, and the remnant vortex of Typhoon Haikui triggering extreme precipitation in South China. Analysis of Typhoon Khanun indicates that, the evolution of large-scale tropical weather systems and the dual-typhoon effect may lead to the two sharp turns of the typhoon’s track.
Using the best track data of China Meteorological Administration (CMA) from 1949 to 2023, real-time operational forecast data of typhoon track and intensity in 2023 from National Meteorological Centre (NMC) of CMA, and the ERA5 reanalysis data from the European Centre for Medium-Range Weather Forecasts (ECMWF), we analyze the main characteristics of typhoon activities in the Western North Pacific in 2023. The results show that in 2023, the numbers of generated typhoons and the landfall typhoons were both at a relatively low level, but the extreme intensity of typhoons and landfall intensities were stronger. The generation source areas of typhoons shifted eastward, with fewer typhoons born in the South China Sea and fewer typhoons making landfall in summer. The landfall localities of typhoons were more concentrated, and the landfall typhoons travelled further inland, causing widespread and severe damages. Although the 24 h typhoon track forecast errors by NMC in 2023 reached a historic low point, the track forecast errors within 1-4 d were higher than those of the Japan Meteorological Agency (JMA) and the U.S. Joint Typhoon Warning Center (JTWC). The intensity forecast errors for typhoons within 1-5 d lead time increased compared to last five years’ levels, but still better than JMA and worse than JTWC. The large challenges in typhoon forecasting in 2023 lay in the inland penetration and prolonged duration of Typhoon Doksuri which brought extreme precipitation in North China, and the remnant vortex of Typhoon Haikui triggering extreme precipitation in South China. Analysis of Typhoon Khanun indicates that, the evolution of large-scale tropical weather systems and the dual-typhoon effect may lead to the two sharp turns of the typhoon’s track.
2025, 51(3):382-388.
DOI: 10.7519/j.issn.1000-0526.2025.012401
Abstract:
The main characteristics of the general atmospheric circulation in December 2024 are as follows. In the Northern Hemisphere, the polar vortex was distributed in a dipole pattern, and the midhigh latitudes of Eurasia had a pattern of two troughs and one ridge. The western Pacific subtropical high was abnormally westward, and the IndoMyanmar trough was weak. Such a circulation pattern was not conducive to the occurrence of precipitation in China. In December, the average precipitation was only 5.3 mm, 55.5% less than normal, ranking the fifth lowest for the same period in history. There was scarce rain and snow in the central and eastern part of China. The number of snowfall days in Beijing, Tianjin and Liaoning was the lowest on record for the same period. Precipitation in Guangdong, Guangxi, Jiangxi, Fujian and other places was reduced by more than 80%, resulting in moderate to severe meteorological drought. The national average temperature was -2.9℃, 0.1℃ higher than in the same period of the normal years. Cold air was active during the month, and four cold air processes appeared, among which the strong cold air from 2 to 3 December led to heavy snow to blizzards in the northeastern part of Heilongjiang, the northeastern part of Inner Mongolia, the northwestern part of Xinjiang and other places. From 28 to 29 December, a wide range of cooling appeared over China, and the temperature in the south to Yangtze River, the eastern part of South China and other places dropped over 12℃ as the consequence of strong cold air. Galeforce winds frequently appeared in northern China during the month, and sanddust weather were observed in some local areas of Inner Mongolia, Gansu and Ningxia. Finally, the overall air diffusion conditions across the country were relatively favorable in this month, and the number of foghaze processes and their intensity were clearly weaker than in the same period of the past decade.
The main characteristics of the general atmospheric circulation in December 2024 are as follows. In the Northern Hemisphere, the polar vortex was distributed in a dipole pattern, and the midhigh latitudes of Eurasia had a pattern of two troughs and one ridge. The western Pacific subtropical high was abnormally westward, and the IndoMyanmar trough was weak. Such a circulation pattern was not conducive to the occurrence of precipitation in China. In December, the average precipitation was only 5.3 mm, 55.5% less than normal, ranking the fifth lowest for the same period in history. There was scarce rain and snow in the central and eastern part of China. The number of snowfall days in Beijing, Tianjin and Liaoning was the lowest on record for the same period. Precipitation in Guangdong, Guangxi, Jiangxi, Fujian and other places was reduced by more than 80%, resulting in moderate to severe meteorological drought. The national average temperature was -2.9℃, 0.1℃ higher than in the same period of the normal years. Cold air was active during the month, and four cold air processes appeared, among which the strong cold air from 2 to 3 December led to heavy snow to blizzards in the northeastern part of Heilongjiang, the northeastern part of Inner Mongolia, the northwestern part of Xinjiang and other places. From 28 to 29 December, a wide range of cooling appeared over China, and the temperature in the south to Yangtze River, the eastern part of South China and other places dropped over 12℃ as the consequence of strong cold air. Galeforce winds frequently appeared in northern China during the month, and sanddust weather were observed in some local areas of Inner Mongolia, Gansu and Ningxia. Finally, the overall air diffusion conditions across the country were relatively favorable in this month, and the number of foghaze processes and their intensity were clearly weaker than in the same period of the past decade.
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ISSN:1000-0526 CN:11-2282/P