The effects of tropical storm on the community structure of Sonneratia caseolaris-Sonneratia apetala(S.caseolaris-S.apetala) artificial mangroves and Ceriops tagal-Rhizophora stylosa(C.tagal-R.stylosa) natural mangrov...The effects of tropical storm on the community structure of Sonneratia caseolaris-Sonneratia apetala(S.caseolaris-S.apetala) artificial mangroves and Ceriops tagal-Rhizophora stylosa(C.tagal-R.stylosa) natural mangroves were analyzed in Dongzhai Harbor in Hainan Island,and the results showed that the average tree height,crown width(CW) in east-west direction(E-W) and north-south direction(N-S) of S.caseolaris-S.apetala artificial mangroves were decreased by 2.8%,14.3% and 12.1% respectively,but the average clear bole height was increased by 60.0% after tropical storm.For C.tagal-R.stylosa natural mangroves,the average tree height and clear bole height were increased by 8.3% and 20.0%,but there was no change in CW(E-W) and CW(N-S).Therefore,tropical storm had greater effects on artificial mangroves than natural mangroves.After tropical storm,tree heights of different species increased in the following sequence:C.tagal>R.stylosa>S.apetala>S.caseolaris,and the sequence of effect degree on CW was C.tagal>R.stylosa>S.caseolaris>S.apetala,while it was C.tagal < R.stylosa < S.caseolaris < S.apetala for clear bole height.Under the effect of tropical storm,the average biomass loss and dry biomass loss of S.caseolaris-S.apetala artificial mangroves were 0.22 and 0.13 t/hm2 respectively,while there was a minimal biomass loss in C.tagal-R.stylosa natural mangroves.On the whole,the wind resistance of natural mangroves was better than artificial mangroves,and that of C.tagal was stronger than R.stylosa,while S.caseolaris was better than S.apetala.展开更多
In order to study the impacts of wind field variations in the middle and lower troposphere on the development and structure of storms,we carried out numerical experiments on cases of severe convection in the Jianghuai...In order to study the impacts of wind field variations in the middle and lower troposphere on the development and structure of storms,we carried out numerical experiments on cases of severe convection in the Jianghuai area under the background of cold vortex on April 28,2015.The results show that the structure and development of convective storms are highly sensitive to the changes of wind fields,and the adjustment of wind fields in the middle or lower troposphere will lead to significant changes in the development and structure of storms.When the wind field in the middle or lower troposphere is weakened,the development of convective storms attenuates to some extent compared with that in the control experiment,and the ways of attenuation in the two experiments are different.In the attenuation test of wind field at the middle level,convective storms obviously weaken at all stages in its development,while for the wind field at the low level,the convective storms weaken only in the initial stage of storm.On the contrary,the enhancement of the wind field in the middle or lower troposphere is conducive to the development of convection,especially the enhancement in the middle troposphere.In contrast,the convective storms develop rapidly in this test,as the most intensive one.The wind field variations have significant impacts on the structure and organization of the storm.The enhancement of wind field in the middle troposphere facilitates the intension of the middle-level rotation in convective storm,the reduction of the storm scale,and the organized evolution of convective storms.The strengthening of the wind field in the lower troposphere is conducive to the development of the low-level secondary circulation of the storm and the cyclonic vorticity at the middle and low levels on the inflowing side of the storms.展开更多
[Objective] The research aimed to study three-dimensional structure and echo characteristic quantity of a supercell storm in central Gansu on May 30,2005.[Method] By monitoring data of Lanzhou CINRAD/CC Doppler radar,...[Objective] The research aimed to study three-dimensional structure and echo characteristic quantity of a supercell storm in central Gansu on May 30,2005.[Method] By monitoring data of Lanzhou CINRAD/CC Doppler radar,the three-dimensional structure characteristics of a rare supercell storm which happened in central Gansu on May 30,2005 were analyzed.We tried to reveal three-dimensional structure and echo characteristic index of supercell storm in the northeast of Qinghai-Tibet Plateau,and find reason of rare heavy hail appearance.[Result] The large-scale strong storm was formed by the common effect of Mongolia cold vortex,low-level jet and ground cold front.When the development of main echo was mature,on reflectivity factor map,it presented obvious inverted 'V' shaped structure in left front of low-level storm,typical hooked and 'person'-type echo characteristics in the right rear.The bounded weak echo zone(vault) in low level corresponded with strong echo overhanging body in high level.It surpassed 60 dBz in the strong reflectivity factor zone.It presented one weak meso-cyclone on corresponding radial velocity map.The jumped increase characteristic of VIL could be as one of indices for judging that hail started to grow.Almost all storms(VILD ≥4.0 g/m3) had more obvious indication significance than VIL for judging heavy hail(diameter ≥20 mm).[Conclusion] The research provided reference for nowcasting of strong convection weather and artificial hail suppression.展开更多
A 5-year mean seasonal analysis of mean storm height data and histograms from the Tropical Rainfall Measuring Mission (TRMM) Precipitation Radar (PR) have been used to study the storm structure of the major climatic r...A 5-year mean seasonal analysis of mean storm height data and histograms from the Tropical Rainfall Measuring Mission (TRMM) Precipitation Radar (PR) have been used to study the storm structure of the major climatic regions in Africa and over the adjacent Atlantic ocean. The analysis was carried out in two ways. First, the mean storm height and histogram were analyzed for the entire continent bounded by 40?N to 40?S and 20?W to 60?E. Secondly, the analysis was carried out on sub-regional basis, on which Africa was structured into ten regions: Desert (North), Semi-desert (north), Deciduous forest (North), Brush Grass Savanna (North), Tropical Rainforest, Deciduous forest (South), Brush Grass-Savanna (South), Temperate Grassland/Montane Forest, Steppe (East) and Atlantic Ocean. As observed over Africa, and some parts of the Atlantic Ocean and the Indian Ocean, the storm height over the land is higher than that over the sea because ground surfaces tend to be heated more and convections are more easily developed over the land than over the Ocean. There are high storm counts over the land at 250 mb whereas the storm counts are high over the Ocean at 700 mb. Over the regions, the vertical structure of the histograms reveals a distinct bi-modal distribution in the northern hemisphere and the southern hemisphere, but a unimodal distribution is close to the equator both in the northern and southern hemisphere.展开更多
After the passage of a cold front, spring in northern China, the outbreak of strong wind is often accompanied by dust emissions. Through analyses of data in the atmospheric boundary layer during a typical case, it is ...After the passage of a cold front, spring in northern China, the outbreak of strong wind is often accompanied by dust emissions. Through analyses of data in the atmospheric boundary layer during a typical case, it is revealed there are rather regular gust wave packets superimposed on the basic strong wind flow. The gust-wind wave packets have a period equal to around 3 6 rains and possess coherent structure. As the vertical transport of momentum is decomposed into separate parts by （a） basic flow, （b） gust-wind, and （c） turbulence, they are all in a downwards direction at the lower levels of the atmospheric boundary layer during strong wind periods. However, （a） is the largest, while （b） and （c） are comparable. All these are very different from the case of normal weather. Besides, the friction velocity at the ground surface is also much larger than that of normal weather and should be corrected by taking the contributions of the basic flow and gust-wind into account.The strong basic flow with descending motion is very favorable for soil erosion and sand/dust emissions, but suppresses the entrainment of dust particles by keeping them within the bottom levels of the atmospheric boundary layer. Owing to the coherent structure of gust-wind, dust particles can effectively overcome the systematic descending air motion and penetrate into the middle and upper levels of the atmospheric boundary layer, and then propagate further and diffuse into the troposphere where ascending air motion prevails.展开更多
Timely and accurate forecasting of storm surges can effectively prevent typhoon storm surges from causing large economic losses and casualties in coastal areas.At present,numerical model forecasting consumes too many ...Timely and accurate forecasting of storm surges can effectively prevent typhoon storm surges from causing large economic losses and casualties in coastal areas.At present,numerical model forecasting consumes too many resources and takes too long to compute,while neural network forecasting lacks regional data to train regional forecasting models.In this study,we used the DUAL wind model to build typhoon wind fields,and constructed a typhoon database of 75 processes in the northern South China Sea using the coupled Advanced Circulation-Simulating Waves Nearshore(ADCIRC-SWAN)model.Then,a neural network with a Res-U-Net structure was trained using the typhoon database to forecast the typhoon processes in the validation dataset,and an excellent storm surge forecasting effect was achieved in the Pearl River Estuary region.The storm surge forecasting effect of stronger typhoons was improved by adding a branch structure and transfer learning.展开更多
We evaluated how historical storm events have shaped the current forest landscape in three Pyrenean subalpine forests(NE Spain).For this purpose we related forest damage estimations obtained from multi-temporal aerial...We evaluated how historical storm events have shaped the current forest landscape in three Pyrenean subalpine forests(NE Spain).For this purpose we related forest damage estimations obtained from multi-temporal aerial photographic comparisons to the current forest typology generated from airborne Li DAR data, and we examined the role of past natural disturbance on the current spatial distribution of forest structural types.We found six forest structural types in the landscape: early regeneration(T1 and T2), young even-aged stands(T3), uneven-aged stands(T4) and adult stands(T5and T6).All of the types were related to the timing and severity of past storms, with early-regeneration structures being found in areas markedly affected in recent times, and adult stands predominating in those areas that had suffered lowest damage levels within the study period.In general, landscapes where high or medium levels of damage were recurrent also presented higher levels of spatial heterogeneity,whereas the opposite pattern was found in the less markedly affected landscape, characterized by thepresence of large regular patches.Our results show the critical role that storm regimes in terms of timing and severity of past storms can play in shaping current forest structure and future dynamics in subalpine forests.The knowledge gained could be used to help define alternative forest management strategies oriented toward the enhancement of landscape heterogeneity as a measure to face future environmental uncertainty.展开更多
A storm track is a region in which synoptic eddy activities are statistically most prevalent and intense. At daily weather charts, it roughly corresponds to the mean trajectories of cyclones and anticyclones. In this ...A storm track is a region in which synoptic eddy activities are statistically most prevalent and intense. At daily weather charts, it roughly corresponds to the mean trajectories of cyclones and anticyclones. In this paper, the recent QuikSCAT （Quick Scatterometer） satellite sea winds data with a 0.5°×0.5° horizontal resolution, and the NCEP （National Centers for Environmental Prediction） 10-m height Gaussian grid wind data and pressure-level reanalysis data, are employed to document the spatial structure of the North Pacific storm track in winter （January） and summer （July） from 1999 to 2005. The results show that in winter the North Pacific storm track is stronger, and is located in lower latitudes with a distinct zonal distribution. In summer, it is weaker, and is located in higher latitudes. Based on the horizontal distributions of geopotential height variance at various levels, three-dimensional schematic diagrams of the North Pacific storm track in winter and summer are extracted and presented. Analyses of the QuikSCAT wind data indicate that this dataset can depict the low-level storm track features in detail. The double storm tracks over the Southern Oceans found by Nakamura and Shimpo are confirmed. More significantly, two new pairs of low-level storm tracks over the North Pacific and the North Atlantic are identified by using this high-resolution dataset. The pair over the North Pacific is focused in this paper, and is named as the ＂subtropical storm track＂ and the ＂subpolar storm track＂, respectively. Moreover, statistical analyses of cyclone and anticyclone trajectories in the winters of 1999 to 2005 reveal as well the existence of the low-level double storm tracks over the North Pacific.展开更多
The inverted charge structure formation of a hailstorm was investigated using the Advanced Weather Research and Forecasting（WRF-ARW） model coupled with electrification and discharge schemes. Different processes may ...The inverted charge structure formation of a hailstorm was investigated using the Advanced Weather Research and Forecasting（WRF-ARW） model coupled with electrification and discharge schemes. Different processes may be responsible for inverted charge structure in different storms and regions.A dynamical-derived mechanism of inverted charge structure formation was confirmed by the numerical model： the inverted structure was formed by strong updraft and downdraft under normal-polarity charging conditions such that the graupel charged negatively in the main charging region in the middle-upper level of the cloud. The simulation results showed the storm presented a normal charge structure before and after hail-fall; while during the hail-fall stage, it showed an inverted charge structure—negative charge region in the upper level of the cloud and a positive charge region in the middle level of the cloud—appearing at the front edge near the strong updraft in the hailstorm. The charging processes between the two particles mainly occurred at the top of the cloud, where the graupel charged negatively and ice crystals positively due to the strong updraft. When the updraft air reached the top of the storm, it would spread to the rear and front. The light ice crystals were transported backward and forward more easily. Meanwhile, the positively charged ice crystals were transported downward by the frontal subsidence, and then a positive charge region formed between the -10°C and -25°C levels. Subsequently, a negative charge region materialized in the upper level of the cloud, and the inverted charge structure formed.展开更多
基金Supported by Scientific Research Special Fund for Public Welfare Industry(2005DIB3J137)National Key Technology R & D Program in the 11th Five year Plan of China(2006BAD03A1402)+1 种基金948 Project of The State Forestry Administration(2006-4-34)The Doctoral Science Foundation of Hainan University(Rndy0703)
文摘The effects of tropical storm on the community structure of Sonneratia caseolaris-Sonneratia apetala(S.caseolaris-S.apetala) artificial mangroves and Ceriops tagal-Rhizophora stylosa(C.tagal-R.stylosa) natural mangroves were analyzed in Dongzhai Harbor in Hainan Island,and the results showed that the average tree height,crown width(CW) in east-west direction(E-W) and north-south direction(N-S) of S.caseolaris-S.apetala artificial mangroves were decreased by 2.8%,14.3% and 12.1% respectively,but the average clear bole height was increased by 60.0% after tropical storm.For C.tagal-R.stylosa natural mangroves,the average tree height and clear bole height were increased by 8.3% and 20.0%,but there was no change in CW(E-W) and CW(N-S).Therefore,tropical storm had greater effects on artificial mangroves than natural mangroves.After tropical storm,tree heights of different species increased in the following sequence:C.tagal>R.stylosa>S.apetala>S.caseolaris,and the sequence of effect degree on CW was C.tagal>R.stylosa>S.caseolaris>S.apetala,while it was C.tagal < R.stylosa < S.caseolaris < S.apetala for clear bole height.Under the effect of tropical storm,the average biomass loss and dry biomass loss of S.caseolaris-S.apetala artificial mangroves were 0.22 and 0.13 t/hm2 respectively,while there was a minimal biomass loss in C.tagal-R.stylosa natural mangroves.On the whole,the wind resistance of natural mangroves was better than artificial mangroves,and that of C.tagal was stronger than R.stylosa,while S.caseolaris was better than S.apetala.
基金National Key R&D Program of China(2017YFC1502104)“333 Project”Program of Jiangsu(BRA2018100)
文摘In order to study the impacts of wind field variations in the middle and lower troposphere on the development and structure of storms,we carried out numerical experiments on cases of severe convection in the Jianghuai area under the background of cold vortex on April 28,2015.The results show that the structure and development of convective storms are highly sensitive to the changes of wind fields,and the adjustment of wind fields in the middle or lower troposphere will lead to significant changes in the development and structure of storms.When the wind field in the middle or lower troposphere is weakened,the development of convective storms attenuates to some extent compared with that in the control experiment,and the ways of attenuation in the two experiments are different.In the attenuation test of wind field at the middle level,convective storms obviously weaken at all stages in its development,while for the wind field at the low level,the convective storms weaken only in the initial stage of storm.On the contrary,the enhancement of the wind field in the middle or lower troposphere is conducive to the development of convection,especially the enhancement in the middle troposphere.In contrast,the convective storms develop rapidly in this test,as the most intensive one.The wind field variations have significant impacts on the structure and organization of the storm.The enhancement of wind field in the middle troposphere facilitates the intension of the middle-level rotation in convective storm,the reduction of the storm scale,and the organized evolution of convective storms.The strengthening of the wind field in the lower troposphere is conducive to the development of the low-level secondary circulation of the storm and the cyclonic vorticity at the middle and low levels on the inflowing side of the storms.
基金Supported by Science Research Special Item of Public Welfare Industry (Meteorology) (GYHY200906024)New Meteorological Technology Spreading Item of China Meteorological Administration(CMATG2009MS38)
文摘[Objective] The research aimed to study three-dimensional structure and echo characteristic quantity of a supercell storm in central Gansu on May 30,2005.[Method] By monitoring data of Lanzhou CINRAD/CC Doppler radar,the three-dimensional structure characteristics of a rare supercell storm which happened in central Gansu on May 30,2005 were analyzed.We tried to reveal three-dimensional structure and echo characteristic index of supercell storm in the northeast of Qinghai-Tibet Plateau,and find reason of rare heavy hail appearance.[Result] The large-scale strong storm was formed by the common effect of Mongolia cold vortex,low-level jet and ground cold front.When the development of main echo was mature,on reflectivity factor map,it presented obvious inverted 'V' shaped structure in left front of low-level storm,typical hooked and 'person'-type echo characteristics in the right rear.The bounded weak echo zone(vault) in low level corresponded with strong echo overhanging body in high level.It surpassed 60 dBz in the strong reflectivity factor zone.It presented one weak meso-cyclone on corresponding radial velocity map.The jumped increase characteristic of VIL could be as one of indices for judging that hail started to grow.Almost all storms(VILD ≥4.0 g/m3) had more obvious indication significance than VIL for judging heavy hail(diameter ≥20 mm).[Conclusion] The research provided reference for nowcasting of strong convection weather and artificial hail suppression.
文摘A 5-year mean seasonal analysis of mean storm height data and histograms from the Tropical Rainfall Measuring Mission (TRMM) Precipitation Radar (PR) have been used to study the storm structure of the major climatic regions in Africa and over the adjacent Atlantic ocean. The analysis was carried out in two ways. First, the mean storm height and histogram were analyzed for the entire continent bounded by 40?N to 40?S and 20?W to 60?E. Secondly, the analysis was carried out on sub-regional basis, on which Africa was structured into ten regions: Desert (North), Semi-desert (north), Deciduous forest (North), Brush Grass Savanna (North), Tropical Rainforest, Deciduous forest (South), Brush Grass-Savanna (South), Temperate Grassland/Montane Forest, Steppe (East) and Atlantic Ocean. As observed over Africa, and some parts of the Atlantic Ocean and the Indian Ocean, the storm height over the land is higher than that over the sea because ground surfaces tend to be heated more and convections are more easily developed over the land than over the Ocean. There are high storm counts over the land at 250 mb whereas the storm counts are high over the Ocean at 700 mb. Over the regions, the vertical structure of the histograms reveals a distinct bi-modal distribution in the northern hemisphere and the southern hemisphere, but a unimodal distribution is close to the equator both in the northern and southern hemisphere.
基金funded by the National Natural Science Foundation of China under Grant Nos.40830103, 40775018, 40875008 and 40605006the science plan in the Chinese Academy of Sciences (KZCX2-YW210)+2 种基金Chinese Academy of Sciences under Grant No.YZ200708through special finance from the China Meteorological Administration(GYHY200706034)the Urban Meteorological Research Foundation (UMRF200810)
文摘After the passage of a cold front, spring in northern China, the outbreak of strong wind is often accompanied by dust emissions. Through analyses of data in the atmospheric boundary layer during a typical case, it is revealed there are rather regular gust wave packets superimposed on the basic strong wind flow. The gust-wind wave packets have a period equal to around 3 6 rains and possess coherent structure. As the vertical transport of momentum is decomposed into separate parts by （a） basic flow, （b） gust-wind, and （c） turbulence, they are all in a downwards direction at the lower levels of the atmospheric boundary layer during strong wind periods. However, （a） is the largest, while （b） and （c） are comparable. All these are very different from the case of normal weather. Besides, the friction velocity at the ground surface is also much larger than that of normal weather and should be corrected by taking the contributions of the basic flow and gust-wind into account.The strong basic flow with descending motion is very favorable for soil erosion and sand/dust emissions, but suppresses the entrainment of dust particles by keeping them within the bottom levels of the atmospheric boundary layer. Owing to the coherent structure of gust-wind, dust particles can effectively overcome the systematic descending air motion and penetrate into the middle and upper levels of the atmospheric boundary layer, and then propagate further and diffuse into the troposphere where ascending air motion prevails.
基金supported by the National Natural Science Foundation of China(Grant No.42076214)Natural Science Foundation of Shandong Province(Grant No.ZR2024QD057).
文摘Timely and accurate forecasting of storm surges can effectively prevent typhoon storm surges from causing large economic losses and casualties in coastal areas.At present,numerical model forecasting consumes too many resources and takes too long to compute,while neural network forecasting lacks regional data to train regional forecasting models.In this study,we used the DUAL wind model to build typhoon wind fields,and constructed a typhoon database of 75 processes in the northern South China Sea using the coupled Advanced Circulation-Simulating Waves Nearshore(ADCIRC-SWAN)model.Then,a neural network with a Res-U-Net structure was trained using the typhoon database to forecast the typhoon processes in the validation dataset,and an excellent storm surge forecasting effect was achieved in the Pearl River Estuary region.The storm surge forecasting effect of stronger typhoons was improved by adding a branch structure and transfer learning.
基金Financial support for this study was provided by the Spanish Ministry of Economy and Competitiveness through the project RESILFOR(AGL2012-40039-C02-01)LC and JRGO were both supported by Ramón y Cajal contracts(RYC-2009-04985 and RYC-2011-08983)
文摘We evaluated how historical storm events have shaped the current forest landscape in three Pyrenean subalpine forests(NE Spain).For this purpose we related forest damage estimations obtained from multi-temporal aerial photographic comparisons to the current forest typology generated from airborne Li DAR data, and we examined the role of past natural disturbance on the current spatial distribution of forest structural types.We found six forest structural types in the landscape: early regeneration(T1 and T2), young even-aged stands(T3), uneven-aged stands(T4) and adult stands(T5and T6).All of the types were related to the timing and severity of past storms, with early-regeneration structures being found in areas markedly affected in recent times, and adult stands predominating in those areas that had suffered lowest damage levels within the study period.In general, landscapes where high or medium levels of damage were recurrent also presented higher levels of spatial heterogeneity,whereas the opposite pattern was found in the less markedly affected landscape, characterized by thepresence of large regular patches.Our results show the critical role that storm regimes in terms of timing and severity of past storms can play in shaping current forest structure and future dynamics in subalpine forests.The knowledge gained could be used to help define alternative forest management strategies oriented toward the enhancement of landscape heterogeneity as a measure to face future environmental uncertainty.
基金Supported by the National Natural Science Foundation of China under Grant No. 40675060Chinese Ministry of Science andTechnology 863 Project under Grant No. 2006AA09Z151+1 种基金China Meteorological Administration under Grant No. GYHY200706031State Oceanic Administration under Grant No. 908-02-03-10
文摘A storm track is a region in which synoptic eddy activities are statistically most prevalent and intense. At daily weather charts, it roughly corresponds to the mean trajectories of cyclones and anticyclones. In this paper, the recent QuikSCAT （Quick Scatterometer） satellite sea winds data with a 0.5°×0.5° horizontal resolution, and the NCEP （National Centers for Environmental Prediction） 10-m height Gaussian grid wind data and pressure-level reanalysis data, are employed to document the spatial structure of the North Pacific storm track in winter （January） and summer （July） from 1999 to 2005. The results show that in winter the North Pacific storm track is stronger, and is located in lower latitudes with a distinct zonal distribution. In summer, it is weaker, and is located in higher latitudes. Based on the horizontal distributions of geopotential height variance at various levels, three-dimensional schematic diagrams of the North Pacific storm track in winter and summer are extracted and presented. Analyses of the QuikSCAT wind data indicate that this dataset can depict the low-level storm track features in detail. The double storm tracks over the Southern Oceans found by Nakamura and Shimpo are confirmed. More significantly, two new pairs of low-level storm tracks over the North Pacific and the North Atlantic are identified by using this high-resolution dataset. The pair over the North Pacific is focused in this paper, and is named as the ＂subtropical storm track＂ and the ＂subpolar storm track＂, respectively. Moreover, statistical analyses of cyclone and anticyclone trajectories in the winters of 1999 to 2005 reveal as well the existence of the low-level double storm tracks over the North Pacific.
基金supported by the National Key Basic Research and Development Program of China (Grant No. 2014CB441406)the National Natural Science Foundation of China (Grant Nos. 91537209 & 41405005)the Basic Research Fund of Chinese Academy of Meteorological Sciences (Grant No. 2014R017)
文摘The inverted charge structure formation of a hailstorm was investigated using the Advanced Weather Research and Forecasting（WRF-ARW） model coupled with electrification and discharge schemes. Different processes may be responsible for inverted charge structure in different storms and regions.A dynamical-derived mechanism of inverted charge structure formation was confirmed by the numerical model： the inverted structure was formed by strong updraft and downdraft under normal-polarity charging conditions such that the graupel charged negatively in the main charging region in the middle-upper level of the cloud. The simulation results showed the storm presented a normal charge structure before and after hail-fall; while during the hail-fall stage, it showed an inverted charge structure—negative charge region in the upper level of the cloud and a positive charge region in the middle level of the cloud—appearing at the front edge near the strong updraft in the hailstorm. The charging processes between the two particles mainly occurred at the top of the cloud, where the graupel charged negatively and ice crystals positively due to the strong updraft. When the updraft air reached the top of the storm, it would spread to the rear and front. The light ice crystals were transported backward and forward more easily. Meanwhile, the positively charged ice crystals were transported downward by the frontal subsidence, and then a positive charge region formed between the -10°C and -25°C levels. Subsequently, a negative charge region materialized in the upper level of the cloud, and the inverted charge structure formed.
