ISSN 1000-0526
CN 11-2282/P
CN 11-2282/P
Volume 50,Issue 7,2024 Table of Contents
2024, 50(7):777-790.
DOI: 10.7519/j.issn.1000-0526.2024.043001
Abstract:
One squall line influenced by the southwest vortex occurred in the eastern part of Sichuan Basin from the night of 4 June to the day of 5 June 2019. Using multisource observation data and ECMWF Reanalysis data, the characteristics and formation of the squall line are analyzed. The results show that convective heavy rainfall before the occurrence of the squall line was formed in the central Sichuan Basin under the background of the highaltitude trough and the warm southwest vortex, combined with troposphere atmospheric environment of the deep wet layer and certain convective available potential energy (CAPE). The squall line occurred during the prominent frontogenesis process of cold front which surmounted the Qinling Mountains and entered the rear of the southwest vortex. With the joint influence of the highaltitude trough, southwest vortex and strong cold front, the cold front vertical circulation merged with the southwest vortex vertical circulation, and the combined vertical circulation circle significantly strengthened the uplift mechanism of the frontal zone, which provided favorable dynamic lifting conditions for the formation of the squall line in western Chongqing. The atmospheric environment in western Chongqing was conducive to the formation of the squall line. There was dry air in the middle troposphere, large vertical temperature lapse rate in the lower and middle troposphere layers, significant CAPE, and large deep vertical wind shear. The formation process of the squall line observed by radar was characterized by the combined development of linear convection with the cold shear line and strong rainfall convection in the southwest vortex frontogenesis region, forming the “herringbone” echo in the west of Chongqing. The cold front behind the “herringbone” echo moved southward, and combined with the evaporation and cooling of raindrops in the dry environment behind the front, cooled down the cold area formed by the rainstorm to the cold pool outflow in the boundary layer, promoting the formation of the squall line. The arcshaped squall line maintained for about 1.5 h after its formation. The southward and downward transport of lowlevel horizontal kinetic energy at the rear of the front area and the enhancing of the potential temperature gradient between the surface cold and warm air during the formation of the squall line all contributed to the formation of the surface gales.
One squall line influenced by the southwest vortex occurred in the eastern part of Sichuan Basin from the night of 4 June to the day of 5 June 2019. Using multisource observation data and ECMWF Reanalysis data, the characteristics and formation of the squall line are analyzed. The results show that convective heavy rainfall before the occurrence of the squall line was formed in the central Sichuan Basin under the background of the highaltitude trough and the warm southwest vortex, combined with troposphere atmospheric environment of the deep wet layer and certain convective available potential energy (CAPE). The squall line occurred during the prominent frontogenesis process of cold front which surmounted the Qinling Mountains and entered the rear of the southwest vortex. With the joint influence of the highaltitude trough, southwest vortex and strong cold front, the cold front vertical circulation merged with the southwest vortex vertical circulation, and the combined vertical circulation circle significantly strengthened the uplift mechanism of the frontal zone, which provided favorable dynamic lifting conditions for the formation of the squall line in western Chongqing. The atmospheric environment in western Chongqing was conducive to the formation of the squall line. There was dry air in the middle troposphere, large vertical temperature lapse rate in the lower and middle troposphere layers, significant CAPE, and large deep vertical wind shear. The formation process of the squall line observed by radar was characterized by the combined development of linear convection with the cold shear line and strong rainfall convection in the southwest vortex frontogenesis region, forming the “herringbone” echo in the west of Chongqing. The cold front behind the “herringbone” echo moved southward, and combined with the evaporation and cooling of raindrops in the dry environment behind the front, cooled down the cold area formed by the rainstorm to the cold pool outflow in the boundary layer, promoting the formation of the squall line. The arcshaped squall line maintained for about 1.5 h after its formation. The southward and downward transport of lowlevel horizontal kinetic energy at the rear of the front area and the enhancing of the potential temperature gradient between the surface cold and warm air during the formation of the squall line all contributed to the formation of the surface gales.
2024, 50(7):791-803.
DOI: 10.7519/j.issn.1000-0526.2024.033002
Abstract:
According to the squall line recognition standards, 36 squall line processes are identified based on the radar composite reflectivity mosaic product in Liaoning Province from May to September 2015-2020. The spatio-temporal distribution of squall line characteristics and several different formation environment characteristics are summarized. The results show that the areas with the maximum frequency of squall line formation in Liaoning Province are from northwestern Liaoning and Chifeng City to Aohan Banner, followed by the west of Bohai Sea to the sea surface of Bohai Strait. The areas with the lowest frequency of squall line formation are the mountain line of Tangshan and Qinhuangdao in the east of Hebei Province. The vast majorities of squall line processes occur in June to August, while the least squall line processes occur in May. Squall lines are mainly formed 〖JP2〗from 12:00 BT to 21:00 BT, in which the period from 14:00 BT to 17:00 BT is the concentration period of squall lines. The coverage of squall line varies from 114 km to 273 km, with maximum reflectivity 65 dBz, average life cycle 3.2 hours and the average moving speed 59.4 km·h-1 (16.5 m·s-1). 33.3% of squall line processes in Liaoning Province are of the fault line type, 19.4% are of the rear extension type, 36.1% are of the fragment type, and 11.1% are the stratiform cloud embedding type. The main organizational form is stratiform cloud trailing type (TS), while the parallel stratiform cloud type (PS) and stratiform cloud leading type (LS) occurrless. 55.6% of squall lines dissipate in the form of reverse broken lines, 8.3% dissipate in the form of contraction lines, and 36.1% dissipate in the form of reverse fault zone. In terms of the circulation situation of squall line formation in Liaoning, the cold vortex front type is the most common, followed by the low trough front type. The special circulation situation of squall line formation in Liaoning is the cold vortex rear type, accounting for 16.7%. The convective available potential energy and the sink convective available potential energy of each circulation pattern show the characteristics of “double 1000”. Different circulation patterns have different characteristics in water vapor supply, stratification instability, vertical wind shear and other physical quantities.
According to the squall line recognition standards, 36 squall line processes are identified based on the radar composite reflectivity mosaic product in Liaoning Province from May to September 2015-2020. The spatio-temporal distribution of squall line characteristics and several different formation environment characteristics are summarized. The results show that the areas with the maximum frequency of squall line formation in Liaoning Province are from northwestern Liaoning and Chifeng City to Aohan Banner, followed by the west of Bohai Sea to the sea surface of Bohai Strait. The areas with the lowest frequency of squall line formation are the mountain line of Tangshan and Qinhuangdao in the east of Hebei Province. The vast majorities of squall line processes occur in June to August, while the least squall line processes occur in May. Squall lines are mainly formed 〖JP2〗from 12:00 BT to 21:00 BT, in which the period from 14:00 BT to 17:00 BT is the concentration period of squall lines. The coverage of squall line varies from 114 km to 273 km, with maximum reflectivity 65 dBz, average life cycle 3.2 hours and the average moving speed 59.4 km·h-1 (16.5 m·s-1). 33.3% of squall line processes in Liaoning Province are of the fault line type, 19.4% are of the rear extension type, 36.1% are of the fragment type, and 11.1% are the stratiform cloud embedding type. The main organizational form is stratiform cloud trailing type (TS), while the parallel stratiform cloud type (PS) and stratiform cloud leading type (LS) occurrless. 55.6% of squall lines dissipate in the form of reverse broken lines, 8.3% dissipate in the form of contraction lines, and 36.1% dissipate in the form of reverse fault zone. In terms of the circulation situation of squall line formation in Liaoning, the cold vortex front type is the most common, followed by the low trough front type. The special circulation situation of squall line formation in Liaoning is the cold vortex rear type, accounting for 16.7%. The convective available potential energy and the sink convective available potential energy of each circulation pattern show the characteristics of “double 1000”. Different circulation patterns have different characteristics in water vapor supply, stratification instability, vertical wind shear and other physical quantities.
2024, 50(7):804-817.
DOI: 10.7519/j.issn.1000-0526.2024.020701
Abstract:
Based on tornado data from the China Meteorological Disaster Encyclopedia (Guangdong Volume)(1959-2000), Guangdong Disaster Prevention and Mitigation Yearbook (2002-2022) and record of on-site disaster investigation of tornadoes in recent years, conventional observations and ERA5 high-resolution reanalysis data, as well as the data from Guangdong Doppler weather radar (2006-2022), we analyze the spatio-temporal distribution and weather background of tornadoes in Guangdong from 1961 to 2022, as well as the morphology of tornado convective storms since 2006. The results are as follows.In the past 62 years, Guangdong has recorded a total of 225 tornadoes. Since 2006 when multiple sources of observation data are relatively complete, about 6 tornadoes have occurred annually. About 50% of tornadoes occurred in the background of tropical cyclone weather, followed by 40% of tornadoes in the westerly weather system, and about 10% of tornadoes were tropical disturbance tornadoes. However, the number of tornadoes fluctuated greatly year by year, up to 17 in 2008. In some years, there was only one tornado or no tornadoes recorded. In general, tornadoes in Guangdong mainly occur from April to September. From April to June, they are mainly westerly tornadoes and from July to September, mainly tropical cyclone tornadoes and tropical disturbance tornadoes. About 85% of tornadoes occur between 06:00-20:00 BT, with the highest occurrence between 14:00-18:00 BT, accounting for about 40%. Tornadoes occur most frequently in the Pearl River Delta, Leizhou Peninsula and Chaoshan Plain. There are few tornadoes in the northern mountainous areas. Foshan, Zhanjiang and Guangzhou are the cities with the highest frequency of tornadoes. About 54% of convective systems generating tornadoes in Guangdong are banded convective systems, which are tropical cyclone tornado parent storms and tropical disturbance tornado parent storms. The storm structures exhibit low centroid characteristics. About 36% are multi-cell storm systems, most of which are westerly tornado parent storms. Different from the tornadoes in the United States that tend to occur in discrete cells and quasi-linear convective systems, the relative frequencies of discrete convection cell and quasi-linear convective systems generating tornadoes in Guangdong are very low, both about 5%. They are the parent storms of the tornadoes in the westerly and their storm structures often show the characteristics of high centroid. More than 90% of tornado mesoscale parent storms have low-level mesocyclones, but only about 47% of the tornado parent storms are accompanied by low-level tornado vortex signature (TVS). Strong tornadoes are typically characterized by low-level mesocyclones with rotational speeds exceeding 20 m·s-1 and TVS velocity differences exceeding 40 m·s-1 .
Based on tornado data from the China Meteorological Disaster Encyclopedia (Guangdong Volume)(1959-2000), Guangdong Disaster Prevention and Mitigation Yearbook (2002-2022) and record of on-site disaster investigation of tornadoes in recent years, conventional observations and ERA5 high-resolution reanalysis data, as well as the data from Guangdong Doppler weather radar (2006-2022), we analyze the spatio-temporal distribution and weather background of tornadoes in Guangdong from 1961 to 2022, as well as the morphology of tornado convective storms since 2006. The results are as follows.In the past 62 years, Guangdong has recorded a total of 225 tornadoes. Since 2006 when multiple sources of observation data are relatively complete, about 6 tornadoes have occurred annually. About 50% of tornadoes occurred in the background of tropical cyclone weather, followed by 40% of tornadoes in the westerly weather system, and about 10% of tornadoes were tropical disturbance tornadoes. However, the number of tornadoes fluctuated greatly year by year, up to 17 in 2008. In some years, there was only one tornado or no tornadoes recorded. In general, tornadoes in Guangdong mainly occur from April to September. From April to June, they are mainly westerly tornadoes and from July to September, mainly tropical cyclone tornadoes and tropical disturbance tornadoes. About 85% of tornadoes occur between 06:00-20:00 BT, with the highest occurrence between 14:00-18:00 BT, accounting for about 40%. Tornadoes occur most frequently in the Pearl River Delta, Leizhou Peninsula and Chaoshan Plain. There are few tornadoes in the northern mountainous areas. Foshan, Zhanjiang and Guangzhou are the cities with the highest frequency of tornadoes. About 54% of convective systems generating tornadoes in Guangdong are banded convective systems, which are tropical cyclone tornado parent storms and tropical disturbance tornado parent storms. The storm structures exhibit low centroid characteristics. About 36% are multi-cell storm systems, most of which are westerly tornado parent storms. Different from the tornadoes in the United States that tend to occur in discrete cells and quasi-linear convective systems, the relative frequencies of discrete convection cell and quasi-linear convective systems generating tornadoes in Guangdong are very low, both about 5%. They are the parent storms of the tornadoes in the westerly and their storm structures often show the characteristics of high centroid. More than 90% of tornado mesoscale parent storms have low-level mesocyclones, but only about 47% of the tornado parent storms are accompanied by low-level tornado vortex signature (TVS). Strong tornadoes are typically characterized by low-level mesocyclones with rotational speeds exceeding 20 m·s-1 and TVS velocity differences exceeding 40 m·s-1 .
2024, 50(7):818-834.
DOI: 10.7519/j.issn.1000-0526.2024.011801
Abstract:
A large-scale convective gale event was studied based on conventional observation data, automa-tic weather station data， 6 h GFS analysis data with 0.25°×0.25° spatial resolution, Doppler radar data, and FY-4 satellite data in East China on 12 April 2020 under the background of consistent northwesterly air flow from the lower to the middle layer behind the North China cold vortex. The results demonstrate that after the strong cold air gales moved southward on the morning of the 12 April, a convective storm was triggered near the drylines at the junction of Shandong and Jiangsu provinces in the afternoon under the favorable thermal background of cold advection at the middle level and warm advection at the lower level. The convective storm occurred in the area with a large temperature difference between 850 hPa and 500 hPa. The convective system was strengthened with favorable conditions such as better water vapor condition, stronger wind speed in the middle layer, merged gust front and the influence of the special land and sea distribution in Hangzhou Bay, which caused the large-scale convective gale weather in Jiangsu, southeastern Anhui and northern Zhejiang again, and the extreme gales at scale 13 near the Zhoushan Islands. The extreme gales occurred at gaps in the convection system and near the northeast side, caused by the rear inflow jet and the intense downdraft, smooth underlying surface, fast-moving convection system and small-scale downburst currents within the system.
A large-scale convective gale event was studied based on conventional observation data, automa-tic weather station data， 6 h GFS analysis data with 0.25°×0.25° spatial resolution, Doppler radar data, and FY-4 satellite data in East China on 12 April 2020 under the background of consistent northwesterly air flow from the lower to the middle layer behind the North China cold vortex. The results demonstrate that after the strong cold air gales moved southward on the morning of the 12 April, a convective storm was triggered near the drylines at the junction of Shandong and Jiangsu provinces in the afternoon under the favorable thermal background of cold advection at the middle level and warm advection at the lower level. The convective storm occurred in the area with a large temperature difference between 850 hPa and 500 hPa. The convective system was strengthened with favorable conditions such as better water vapor condition, stronger wind speed in the middle layer, merged gust front and the influence of the special land and sea distribution in Hangzhou Bay, which caused the large-scale convective gale weather in Jiangsu, southeastern Anhui and northern Zhejiang again, and the extreme gales at scale 13 near the Zhoushan Islands. The extreme gales occurred at gaps in the convection system and near the northeast side, caused by the rear inflow jet and the intense downdraft, smooth underlying surface, fast-moving convection system and small-scale downburst currents within the system.
2024, 50(7):835-846.
DOI: 10.7519/j.issn.1000-0526.2023.082101
Abstract:
Based on CMA besttrack and ECMWF fine grid data, 16 environmental variables during TC genesis are calculated and 7 prediction factors with significance are selected. The stepwise regression algorithm based on double test was used in establishing the TC genesis forecasting equation. The independent sample test results show that the hit rate of the wind speed predicted by the regression method is higher than that of the wind speed and pressure predicted by the numerical model. In 2022, the stepwise regression algorithm based on double test was trialed in the TC genesis forecasting operation. The test results of generating forecast for Typhoon Chaba showed that the regression method has a good performance, and it can provide a reference for forecasters to judge whether and when the typhoon is generated.
Based on CMA besttrack and ECMWF fine grid data, 16 environmental variables during TC genesis are calculated and 7 prediction factors with significance are selected. The stepwise regression algorithm based on double test was used in establishing the TC genesis forecasting equation. The independent sample test results show that the hit rate of the wind speed predicted by the regression method is higher than that of the wind speed and pressure predicted by the numerical model. In 2022, the stepwise regression algorithm based on double test was trialed in the TC genesis forecasting operation. The test results of generating forecast for Typhoon Chaba showed that the regression method has a good performance, and it can provide a reference for forecasters to judge whether and when the typhoon is generated.
2024, 50(7):847-858.
DOI: 10.7519/j.issn.1000-0526.2024.020401
Abstract:
This study uses observation data from stations in the eastern Southwest China and ERA5 reanalysis data and analyzes the characteristics and causes of the inverse phase shift anomalies in winter temperatures (referred to as anomalous shifts) in this region. The findings indicate that after 2000, this region tended to experience a pattern of colder temperatures earlier in the winter followed by warmer temperatures later (referred to as P1 type), whereas a pattern of warmer temperatures followed by colder ones (referred to as P2 type) was more prevalent in the 1970s. During the occurrence of these anomalous shifts in winter temperatures, the 500 hPa geopotential height field reveals that the Tibetan Plateau plays a cru-cial role in the circulation system, even surpassing the influence of the Ural blocking high. At the 200 hPa wind field, systems such as the westerly jet stream affect the East Asian winter monsoon influencing the intra-seasonal variation of temperature in winter. In terms of sea-level pressure fields, when the Mongolian high exhibits significant weakening after an initial strengthening in winter, P1 type temperature shifts are more likely to occur, and vice versa for P2 type shifts. Additionally, during these anomalous temperature shifts within the winter season, significant anomaly signals have been observed in the North Atlantic, the equatorial central and eastern Pacific and the equatorial Indian Ocean. High sea surface temperature anomalies in these three areas during the preceding summer and autumn seasons tend to cause P1 type shifts in winter temperatures, whereas the opposite conditions tend to result in P2 type shifts. Thus, abnormal sea surface temperature can serve as potential precursors for prediction.
This study uses observation data from stations in the eastern Southwest China and ERA5 reanalysis data and analyzes the characteristics and causes of the inverse phase shift anomalies in winter temperatures (referred to as anomalous shifts) in this region. The findings indicate that after 2000, this region tended to experience a pattern of colder temperatures earlier in the winter followed by warmer temperatures later (referred to as P1 type), whereas a pattern of warmer temperatures followed by colder ones (referred to as P2 type) was more prevalent in the 1970s. During the occurrence of these anomalous shifts in winter temperatures, the 500 hPa geopotential height field reveals that the Tibetan Plateau plays a cru-cial role in the circulation system, even surpassing the influence of the Ural blocking high. At the 200 hPa wind field, systems such as the westerly jet stream affect the East Asian winter monsoon influencing the intra-seasonal variation of temperature in winter. In terms of sea-level pressure fields, when the Mongolian high exhibits significant weakening after an initial strengthening in winter, P1 type temperature shifts are more likely to occur, and vice versa for P2 type shifts. Additionally, during these anomalous temperature shifts within the winter season, significant anomaly signals have been observed in the North Atlantic, the equatorial central and eastern Pacific and the equatorial Indian Ocean. High sea surface temperature anomalies in these three areas during the preceding summer and autumn seasons tend to cause P1 type shifts in winter temperatures, whereas the opposite conditions tend to result in P2 type shifts. Thus, abnormal sea surface temperature can serve as potential precursors for prediction.
2024, 50(7):859-867.
DOI: 10.7519/j.issn.1000-0526.2024.042601
Abstract:
Based on the characteristics of simultaneous observation of cloud tops by ground-based millimeter-wave cloud radar and FY-4A satellite, the relationship between cloud top height observed by cloud radar and AGRI load channel data of FY-4A satellite is analyzed, and a joint retrieving method of cloud top height based on cloud radar and FY-4A satellite is proposed. The cloud top height of the satellite in an area around the installation point of the cloud radar is retrieved, and the retrieval results are verified and analyzed. The results show that the 11-14 channel values of FY-4A satellite are linearly correlated to the cloud top height of cloud radar. Moreover, the ratio of FY-4A satellite channel values to cloud top height observed by cloud radar shows the seasonal characteristics of minimum in winter, followed by spring and autumn, and maximum in summer. The correlation coefficient between cloud top height obtained from satellite-ground fusion inversion and cloud top height measured by cloud radar is 0.84, and the root-mean-square error is reduced by 0.7 km after fusion, which improves the inversion accuracy of satellite cloud top height.
Based on the characteristics of simultaneous observation of cloud tops by ground-based millimeter-wave cloud radar and FY-4A satellite, the relationship between cloud top height observed by cloud radar and AGRI load channel data of FY-4A satellite is analyzed, and a joint retrieving method of cloud top height based on cloud radar and FY-4A satellite is proposed. The cloud top height of the satellite in an area around the installation point of the cloud radar is retrieved, and the retrieval results are verified and analyzed. The results show that the 11-14 channel values of FY-4A satellite are linearly correlated to the cloud top height of cloud radar. Moreover, the ratio of FY-4A satellite channel values to cloud top height observed by cloud radar shows the seasonal characteristics of minimum in winter, followed by spring and autumn, and maximum in summer. The correlation coefficient between cloud top height obtained from satellite-ground fusion inversion and cloud top height measured by cloud radar is 0.84, and the root-mean-square error is reduced by 0.7 km after fusion, which improves the inversion accuracy of satellite cloud top height.
2024, 50(7):868-876.
DOI: 10.7519/j.issn.1000-0526.2024.012301
Abstract:
Based on the hourly rainfall data of 2066 automatic weather stations and rainstorm disaster information in Chongqing from 2011 to 2021, the rainstorm process slide sampling and percentile method are used to determine the rainstorm warning signal standards for counties and the disaster risk warning grades for the whole city， which is expected to provide some references for Chongqing local departments to initiate rainstorm emergency response. The main conclusions are as follows. A total of 5363 rainstorm processes occurred in 34 counties with meteorological services in Chongqing, with an average of 14.3 times per year in each county. The time lengths of 1, 3 and 12 h are selected as the reference durations for issuing rainstorm process warning signals. Rainstorm warning signal (blue, yellow, orange, and red) standard thresholds of different durations are obtained by sorting the rainfall data in ascending order to the nearest value within the 30%-50%, 70%-80%, 90%-95%, and 99%-99.9% percentile ranges, and they are 1 h-30-50-70-100 mm, 3 h-50-70-100-150 mm and 12 h-70-100-150-250 mm. The probability of disaster indicated by different warning signals increases with signal level and duration. Warning signals of blue, yellow, orange and red for each county have an average of 5.4, 4.0, 1.3 and 0.18 times per year according to the highest warning level of different durations, and the disaster probability of different warning signals are 30%, 60%, 85%, and 95% respectively. A total of 114 regional rainstorm processes occurred in the whole city of Chongqing from 2011 to 2021, and rainstorm disaster risk warning levels determined by the number of possible disaster counties have an average of 5.3 (Ⅳ), 3.1 (Ⅲ), 1.6 (Ⅱ) and 0.1 (Ⅰ) times per year. This is basically consistent with the frequency of counties and conforms to the regularity of warning releases.
Based on the hourly rainfall data of 2066 automatic weather stations and rainstorm disaster information in Chongqing from 2011 to 2021, the rainstorm process slide sampling and percentile method are used to determine the rainstorm warning signal standards for counties and the disaster risk warning grades for the whole city， which is expected to provide some references for Chongqing local departments to initiate rainstorm emergency response. The main conclusions are as follows. A total of 5363 rainstorm processes occurred in 34 counties with meteorological services in Chongqing, with an average of 14.3 times per year in each county. The time lengths of 1, 3 and 12 h are selected as the reference durations for issuing rainstorm process warning signals. Rainstorm warning signal (blue, yellow, orange, and red) standard thresholds of different durations are obtained by sorting the rainfall data in ascending order to the nearest value within the 30%-50%, 70%-80%, 90%-95%, and 99%-99.9% percentile ranges, and they are 1 h-30-50-70-100 mm, 3 h-50-70-100-150 mm and 12 h-70-100-150-250 mm. The probability of disaster indicated by different warning signals increases with signal level and duration. Warning signals of blue, yellow, orange and red for each county have an average of 5.4, 4.0, 1.3 and 0.18 times per year according to the highest warning level of different durations, and the disaster probability of different warning signals are 30%, 60%, 85%, and 95% respectively. A total of 114 regional rainstorm processes occurred in the whole city of Chongqing from 2011 to 2021, and rainstorm disaster risk warning levels determined by the number of possible disaster counties have an average of 5.3 (Ⅳ), 3.1 (Ⅲ), 1.6 (Ⅱ) and 0.1 (Ⅰ) times per year. This is basically consistent with the frequency of counties and conforms to the regularity of warning releases.
2024, 50(7):877-886.
DOI: 10.7519/j.issn.1000-0526.2024.051701
Abstract:
Based on the outpatient and inpatient data of heatstroke in Tianjin from 2016 to 2020, a comparative analysis of the relationship between meteorological factors and the heatstroke outpatient rate is conducted using the Generalized Additive Modeland Distributed Lag Nonlinear Model. By introducing the human heat balance model and predicted mean vote (PMV), a localized heatstroke meteorological risk warning index is established. The results show that the numbers of outpatient and inpatient cases of heatstroke in Tianjin are concentrated from late June to early August each year, with 84% of the peak heatstroke days occurring in 6 continuous weather processes over the 5 years. The occurrence of heatstroke is most correlated 〖JP〗with the meteorological conditions of that day and the previous day. There is a significant increase in heatstroke cases when the maximum temperature exceeds 35℃. Males are more susceptible to heatstroke than females, and the outpatient rate of the elderly is significantly higher than the general population. The heatstroke outpatient rate is positively correlated to average temperature, maximum temperature, relative humidity, and solar radiation intensity, with the strongest correlation with average temperature but a negative correlation with wind speed. Introducing the human heat balance model, PMV shows a higher correlation with the heatstroke outpatient rate than any single meteorological factor, indicating PMV has a clear advantage in evaluating heatstroke meteorological risk. A forecasting equation with PMV as the key indicator is developed.
Based on the outpatient and inpatient data of heatstroke in Tianjin from 2016 to 2020, a comparative analysis of the relationship between meteorological factors and the heatstroke outpatient rate is conducted using the Generalized Additive Modeland Distributed Lag Nonlinear Model. By introducing the human heat balance model and predicted mean vote (PMV), a localized heatstroke meteorological risk warning index is established. The results show that the numbers of outpatient and inpatient cases of heatstroke in Tianjin are concentrated from late June to early August each year, with 84% of the peak heatstroke days occurring in 6 continuous weather processes over the 5 years. The occurrence of heatstroke is most correlated 〖JP〗with the meteorological conditions of that day and the previous day. There is a significant increase in heatstroke cases when the maximum temperature exceeds 35℃. Males are more susceptible to heatstroke than females, and the outpatient rate of the elderly is significantly higher than the general population. The heatstroke outpatient rate is positively correlated to average temperature, maximum temperature, relative humidity, and solar radiation intensity, with the strongest correlation with average temperature but a negative correlation with wind speed. Introducing the human heat balance model, PMV shows a higher correlation with the heatstroke outpatient rate than any single meteorological factor, indicating PMV has a clear advantage in evaluating heatstroke meteorological risk. A forecasting equation with PMV as the key indicator is developed.
2024, 50(7):887-896.
DOI: 10.7519/j.issn.1000-0526.2024.052201
Abstract:
Based on the observational datasets from National Meteorological Information Centre, and NCEP/NCAR reanalysis data, characteristics of spatio-temporal distribution of climate anomalies in the winter of 2023/2024 and possible causes and mechanisms are analyzed. During the 2023/2024 winter, average temperature in China was 0.3℃ higher than climatology. The fluctuation of temperature was significant, with an intra-seasonal variation feature of being warmer in the early winter but colder in the late winter. Average precipitation was more than normal by 19.8%, and most parts of central and eastern China received more precipitation above normal. The power of East Asian winter monsoon and the intensity of Siberian high were near the normal values, and the East Asian trough was in a weakened condition. 500 hPa geopotential height in the middle and high latitudes of Eurasia was low in the west but high in the east, featured with significant intra-seasonal fluctuation. Zonal atmospheric circulation prevailed in December 2023 and January 2024, and then it turned into abnormal meridional patterns in February 2024, which was favorable for the southward invasion of cold air in middle and high latitudes into China. In response to the synergistic effect of El Ni〖AKn~D〗o mature phase, warm tropical Indian Ocean and Atlantic Ocean, cold phase of Pacific interdecadal oscillation, an anomalous anticyclone was formed in the western North Pacific, being active over the Philippines and the South China Sea in stages. Western Pacific subtropical high intensified and extended westward. A Rossby wave train propagated along westerly jet in the upper troposphere, which was beneficial for the water vapor transport into central and eastern China. Finally, the confluence of this warm-moist air and the southward cold air from the middle and high latitudes led to the frequent snow and rain processes in the central and eastern parts of China.
Based on the observational datasets from National Meteorological Information Centre, and NCEP/NCAR reanalysis data, characteristics of spatio-temporal distribution of climate anomalies in the winter of 2023/2024 and possible causes and mechanisms are analyzed. During the 2023/2024 winter, average temperature in China was 0.3℃ higher than climatology. The fluctuation of temperature was significant, with an intra-seasonal variation feature of being warmer in the early winter but colder in the late winter. Average precipitation was more than normal by 19.8%, and most parts of central and eastern China received more precipitation above normal. The power of East Asian winter monsoon and the intensity of Siberian high were near the normal values, and the East Asian trough was in a weakened condition. 500 hPa geopotential height in the middle and high latitudes of Eurasia was low in the west but high in the east, featured with significant intra-seasonal fluctuation. Zonal atmospheric circulation prevailed in December 2023 and January 2024, and then it turned into abnormal meridional patterns in February 2024, which was favorable for the southward invasion of cold air in middle and high latitudes into China. In response to the synergistic effect of El Ni〖AKn~D〗o mature phase, warm tropical Indian Ocean and Atlantic Ocean, cold phase of Pacific interdecadal oscillation, an anomalous anticyclone was formed in the western North Pacific, being active over the Philippines and the South China Sea in stages. Western Pacific subtropical high intensified and extended westward. A Rossby wave train propagated along westerly jet in the upper troposphere, which was beneficial for the water vapor transport into central and eastern China. Finally, the confluence of this warm-moist air and the southward cold air from the middle and high latitudes led to the frequent snow and rain processes in the central and eastern parts of China.
2024, 50(7):897-904.
DOI: 10.7519/j.issn.1000-0526.2024.062601
Abstract:
The main characteristics of the general atmospheric circulation in April 2024 are as follows. There existed one polar vortex center stronger than usual in the Northern Hemisphere, located on the ocean surface southwest of New Siberian Islands. The circulation in middle-high latitudes showed a four-wave pattern, and there was a positive anomaly of the geopotential height over China. The strength of western Pacific subtropical high was stronger and more northward than that in normal years. The monthly mean temperature was 13.2℃, 1.7℃ higher than the normal value 11.5℃. The monthly average rainfall reached 79.1 mm, 65% more than in normal period (43.6 mm), both of the average temperature and rainfall peaked the record in the same〖JP2〗 period since 1961. During this month, there was only one major cold air event, ten severe convection processes and seven large-scale regional rainfall processes affecting China, these events were mainly concentrated in southern China with higher frequency than normal. In addition, six sand-dust events influenced the northern part of China, and the drought in Southwest China was developing in stages.
The main characteristics of the general atmospheric circulation in April 2024 are as follows. There existed one polar vortex center stronger than usual in the Northern Hemisphere, located on the ocean surface southwest of New Siberian Islands. The circulation in middle-high latitudes showed a four-wave pattern, and there was a positive anomaly of the geopotential height over China. The strength of western Pacific subtropical high was stronger and more northward than that in normal years. The monthly mean temperature was 13.2℃, 1.7℃ higher than the normal value 11.5℃. The monthly average rainfall reached 79.1 mm, 65% more than in normal period (43.6 mm), both of the average temperature and rainfall peaked the record in the same〖JP2〗 period since 1961. During this month, there was only one major cold air event, ten severe convection processes and seven large-scale regional rainfall processes affecting China, these events were mainly concentrated in southern China with higher frequency than normal. In addition, six sand-dust events influenced the northern part of China, and the drought in Southwest China was developing in stages.
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ISSN:1000-0526 CN:11-2282/P