In this study,we examine the dynamics and microphysical structures of a deep compact thunderstorm event driving cloud-to-ground(CG)lightning over the Nanjing area located within the Yangtze-Huai River Basin(YHRB)durin...In this study,we examine the dynamics and microphysical structures of a deep compact thunderstorm event driving cloud-to-ground(CG)lightning over the Nanjing area located within the Yangtze-Huai River Basin(YHRB)during the monsoon break period.The microphysical structures combined with the dynamics in the glaciated,mixed-phase,and warm-phase layers during the formative,intensifying,and mature stages of the thunderstorm were first investigated using C-band polarimetric radar and CG lightning observations.The results show that the mature phase of the thunderstorm produced a local cold pool,which collided with a southerly warm wind,resulting in a strong updraft.The strong updraft favored the lifting of raindrops to the mixed-phase region to form abundant supercooled liquid water and graupel.From the formative stage to the developing stage and further to the mature stage,increased ZH-and reduced ZDR-values within the mixed-phase region are found,especially within the strong updraft region(>5 m s^(-1)).This phenomenon suggests that supercooled raindrops evolved into large hydrometeors(graupel and hail),indicative of a strong riming process.The signatures within this region are consistent with a favorable environment for thunderstorm electrification and generate the most frequent lightning during the thunderstorm life cycle.展开更多
By using the conventional observations, radar data, NCEP/NCAR FNL 1°×1° reanalysis data and numerical simulation data and with the construction and calculation of radar echo parameters, this paper prese...By using the conventional observations, radar data, NCEP/NCAR FNL 1°×1° reanalysis data and numerical simulation data and with the construction and calculation of radar echo parameters, this paper presents the structural characteristics and physical processes of a short-time heavy precipitation supercell that occurred in the squall line process in Shanxi Province on 24 June 2020. The results show that this squall line event occurred in front of a surface cold front,combined with infiltration of low-level cold air and continuous increase of near-surface humidity in the afternoon. The surface mesoscale convergence line and mesoscale dew point front contributed to the development and systemization of the squall line by a large degree. The short-time extremely heavy precipitation in Pingshun County was caused by the development of a supercell from thunderstorm cells on the front side of the squall line. The characteristics of sharp increase in vertical integral liquid water content, persistent increase in reflectivity factor and continuous rise in the echo top height appeared about 23 min earlier than the severe precipitation, which has qualitative indicating significance for the nowcasting of short-time heavy precipitation. A quantitative analysis of the radar echo parameters suggests that the“sudden drop”of FV40was a precursor signal of cells’ coalescence and rapid development to the mature stage. The areal change of the echo core at the 6 km height was highly subject to the merging and developing of cells, the rapid change of hydrometeor particles in clouds and the precipitation intensity. Changes in the cross-sectional area of convective cells at different heights can indirectly reflect the changes of liquid particles and ice particles in clouds, which is indicatively meaningful for predicting the coalescing and developing-to-maturing of cells and heavy precipitation 30-45 min earlier.A comprehensive echo parameter prediction model constructed by the random forest principle can predict the magnitude of short-time heavy precipitation 40-50 min in advance. Numerical simulation reveals that large amounts of water vapor existed in the near-surface atmosphere, and that the cells rapidly obtained moisture from the ambient atmosphere and developed rapidly through maternal feeding. The cold cloud zone was narrow, upright and had a high stretch height. The upward motion in clouds was strong and deep, and very rich in liquid water content. The graupel particles had a large vertical distribution range, the coexistence area of graupel and snow was large, the height of raindrops was close to the surface with a wide horizontal scale, and the precipitation efficiency was high. These may be the important elements responsible for the occurrence of the short-time heavy precipitation that exceeded historical extreme values. On the basis of the above analyses, a comprehensive parameter(CP) prediction model is worked out, which can estimate the developing trend of supercells and the intensity of short-time heavy precipitation about 1 h in advance.展开更多
The microphysical structure of snow clouds and the growth process of snow crystals were observed by means of instrumented aircraft, weather radar, snow crystal observations etc. in Urumqi region during the winter of 1...The microphysical structure of snow clouds and the growth process of snow crystals were observed by means of instrumented aircraft, weather radar, snow crystal observations etc. in Urumqi region during the winter of 1982. The analysis of three cases show that about 70% of snow mass growth is produced in the lower layer below 2000 m under the cold front, and that the concentration of ice crystals is as high as 60 L^(-1) and the supercooled water is absent in lower clouds. We may infer that the deposition of ice crystals and the aggregation of snow crystals are important processes for the snow development. The microphysical structure of the snow band near the front aloft and its characteristics as a seeder cloud are also described in this paper.展开更多
During the period of the super typhoon"Lekima"(No.1909)landed on the coast of North China,a high-resolution numerical simulation study was carried out with the WRF model on the clouds microphysical process o...During the period of the super typhoon"Lekima"(No.1909)landed on the coast of North China,a high-resolution numerical simulation study was carried out with the WRF model on the clouds microphysical process of heavy precipitation.The results showed that(1)the water vapor convergence tended to develop and strengthen on the way forward of typhoon center,and the evolution of water vapor convergence zone was closely related to the development of typhoon asymmetric structure,and had a good corresponding relationship with the falling zone of the rainstorm.(2)The eastern coast of Hebei was located in the big-value area of water vapor transport belt in the northwest quadrant of the typhoon.Below 850 hPa,northeast wind appeared,and warm humid water vapor was transported from marine area to terrestrial by typhoon.Affected by upper-level westerly trough,westerly wind was dominated above 700 hPa,and water vapor convergence was transported from low level to upper level,and several rainstorm center appeared.(3)In the spiral rain bands of typhoon,the big-value center of graupel particles cooperated with the warm cloud enriched with water content,and the ground would produce a center of heavy precipitation,and the precipitation center of pure warm cloud appeared in 117.5°E.This phenomenon rarely occurred during continental cloud precipitation.Therefore,the contribution of warm cloud precipitation mechanism to the typhoon spiral rain belt should be emphasized.展开更多
To analyze the effects of gas cannons on clouds and precipitation,multisource observational data,including those from National Centers for Environmental Prediction(NCEP)reanalysis,Hangzhou and Huzhou new-generation we...To analyze the effects of gas cannons on clouds and precipitation,multisource observational data,including those from National Centers for Environmental Prediction(NCEP)reanalysis,Hangzhou and Huzhou new-generation weather radars,laser disdrometer,ground-based automatic weather station,wind profiler radar,and Lin'an C-band dualpolarization radar,were adopted in this study.Based on the variational dual-Doppler wind retrieval method and the polarimetric variables obtained by the dual-polarization radar,we analyzed the microphysical processes and the variations in the macro-and microphysical quantities in clouds from the perspective of the synoptic background before precipitation enhancement,the polarization echo characteristics before,during and after enhancement,and the evolution of the fine three-dimensional kinematic structure and the microphysical structure.The results show that the precipitation enhancement operation promoted the development of radar echoes and prolonged their duration,and both the horizontal and vertical wind speeds increased.The dual-polarization radar echo showed that the diameter of the precipitation particles increased,and the concentration of raindrops increased after precipitation enhancement.The raindrops were lifted to a height corresponding to 0 to-20℃due to vertical updrafts.Based on the disdrometer data during precipitation enhancement,the concentration of small raindrops(lgN_(w))showed a significant increase,and the mass-weighted diameter D_(m)value decreased,indicating that the precipitation enhancement operation played a certain“lubricating”effect.After the precipitation enhancement,the concentration of raindrops did not change much compared with that during the enhancement process,while the Dm increased,corresponding to an increase in rain intensity.The results suggest the positive effect of gas cannons on precipitation enhancement.展开更多
In this study, the vertical profiles of radar refractive factor(Z) observed with an X-band Doppler radar in Jurong on July 13, 2012 in different periods of a stratiform cloud precipitation process were simulated using...In this study, the vertical profiles of radar refractive factor(Z) observed with an X-band Doppler radar in Jurong on July 13, 2012 in different periods of a stratiform cloud precipitation process were simulated using the Sim RAD software, and the contributions of each impact resulting in the bright band were analyzed quantitatively. In the simulation, the parameters inputted into Sim RAD were updated until the output Z profile was nearly consistent with the observation. The input parameters were then deemed to reflect real conditions of the cloud and precipitation. The results showed that a wider(narrower) and brighter(darker) bright band corresponded to a larger(smaller) amount, wider(narrower) vertical distribution, and larger(smaller) mean diameter of melting particles in the melting layer. Besides this,radar reflectivity factors under the wider(narrower) melting layer were larger(smaller). This may be contributed to the adequate growth of larger rain drops in the upper melting layer. Sensitivity experiments of the generation of the radar bright band showed that a drastic increasing of the complex refractive index due to melting led to the largest impact,making the radar reflectivity factor increase by about 15 d BZ. Fragmentation of large particles was the second most important influence, making the value decrease by 10 d BZ. The collision-coalescence between melting particles, volumetric shrinking due to melting, and the falling speed of raindrops made the radar reflectivity factor change by about 3-7d BZ. Shape transformation from spheres to oblate ellipsoids resulted in only a slight increase in the radar reflectivity factors(about 0.2 d BZ), which might be due to the fact that there are few large particles in stratiform cloud.展开更多
The weather research and forecasting（WRF） model is a new generation mesoscale numerical model with a fine grid resolution（2 km）, making it ideal to simulate the macro-and micro-physical processes and latent heatin...The weather research and forecasting（WRF） model is a new generation mesoscale numerical model with a fine grid resolution（2 km）, making it ideal to simulate the macro-and micro-physical processes and latent heating within Typhoon Molave（2009）. Simulations based on a single-moment, six-class microphysical scheme are shown to be reasonable, following verification of results for the typhoon track, wind intensity, precipitation pattern, as well as inner-core thermodynamic and dynamic structures. After calculating latent heating rate, it is concluded that the total latent heat is mainly derived from condensation below the zero degree isotherm, and from deposition above this isotherm. It is revealed that cloud microphysical processes related to graupel are the most important contributors to the total latent heat. Other important latent heat contributors in the simulated Typhoon Molave are condensation of cloud water, deposition of cloud ice, deposition of snow, initiation of cloud ice crystals, deposition of graupel, accretion of cloud water by graupel, evaporation of cloud water and rainwater,sublimation of snow, sublimation of graupel, melting of graupel, and sublimation of cloud ice. In essence, the simulated latent heat profile is similar to ones recorded by the Tropical Rainfall Measuring Mission, although specific values differ slightly.展开更多
Cloud microphysical data observed with PMS probes have been combined with radar and other in-situ data collected by a NOAA P-3 aircraft that flew through the stratiform and transition regions of a mesoscale convective...Cloud microphysical data observed with PMS probes have been combined with radar and other in-situ data collected by a NOAA P-3 aircraft that flew through the stratiform and transition regions of a mesoscale convective complex(MCC).The combined data have been analyzed with respect to the mescscale structure of the storm systems.The characteristics of ice particles in the transition and stratiform regions were quite differeat.The ice particle concentrations in the transition region were about 4 to 6 times that found in the stratiform region,and the size of ice particles in the stratiform region was about twice that in the transition region.The relatively lower radar reflectivity in the transition region is a result of smaller particle sizes.The main precipitation particle growth mechanisms are riming and aggregation in the transition region ard the aggregation process predominates in the stratiform region referred from the microphysical structures.The ag- gregation starts in the upper,colder levls but becomes more efficient as the particles approach the melting layer.展开更多
基金primarily supported by the National Natural Science Foundation of China(Grant Nos.42025501,41805025,42175005,and 61827901)the National Key R&D Program of China(2022YFC3003905)+5 种基金the National Key Laboratory on Electromagnetic Environmental Effects and Electro-optical Engineering(NO.JCKYS61422062101)the Meteorological Union Fund of the National Natural Science Foundation of China(U2142203)the Foundation of Jiangsu Provincial Meteorological Bureau(KM202308)The Open Grants of China Meteorological Administration Radar Meteorology Key Laboratory(2023LRMB04)S&T Development Fund of NJIAS(KJF202307)the Open Research Program of the State Key Laboratory of Severe Weather(2022LASW-A01)。
文摘In this study,we examine the dynamics and microphysical structures of a deep compact thunderstorm event driving cloud-to-ground(CG)lightning over the Nanjing area located within the Yangtze-Huai River Basin(YHRB)during the monsoon break period.The microphysical structures combined with the dynamics in the glaciated,mixed-phase,and warm-phase layers during the formative,intensifying,and mature stages of the thunderstorm were first investigated using C-band polarimetric radar and CG lightning observations.The results show that the mature phase of the thunderstorm produced a local cold pool,which collided with a southerly warm wind,resulting in a strong updraft.The strong updraft favored the lifting of raindrops to the mixed-phase region to form abundant supercooled liquid water and graupel.From the formative stage to the developing stage and further to the mature stage,increased ZH-and reduced ZDR-values within the mixed-phase region are found,especially within the strong updraft region(>5 m s^(-1)).This phenomenon suggests that supercooled raindrops evolved into large hydrometeors(graupel and hail),indicative of a strong riming process.The signatures within this region are consistent with a favorable environment for thunderstorm electrification and generate the most frequent lightning during the thunderstorm life cycle.
基金National Natural Science Foundation of China(41475050)。
文摘By using the conventional observations, radar data, NCEP/NCAR FNL 1°×1° reanalysis data and numerical simulation data and with the construction and calculation of radar echo parameters, this paper presents the structural characteristics and physical processes of a short-time heavy precipitation supercell that occurred in the squall line process in Shanxi Province on 24 June 2020. The results show that this squall line event occurred in front of a surface cold front,combined with infiltration of low-level cold air and continuous increase of near-surface humidity in the afternoon. The surface mesoscale convergence line and mesoscale dew point front contributed to the development and systemization of the squall line by a large degree. The short-time extremely heavy precipitation in Pingshun County was caused by the development of a supercell from thunderstorm cells on the front side of the squall line. The characteristics of sharp increase in vertical integral liquid water content, persistent increase in reflectivity factor and continuous rise in the echo top height appeared about 23 min earlier than the severe precipitation, which has qualitative indicating significance for the nowcasting of short-time heavy precipitation. A quantitative analysis of the radar echo parameters suggests that the“sudden drop”of FV40was a precursor signal of cells’ coalescence and rapid development to the mature stage. The areal change of the echo core at the 6 km height was highly subject to the merging and developing of cells, the rapid change of hydrometeor particles in clouds and the precipitation intensity. Changes in the cross-sectional area of convective cells at different heights can indirectly reflect the changes of liquid particles and ice particles in clouds, which is indicatively meaningful for predicting the coalescing and developing-to-maturing of cells and heavy precipitation 30-45 min earlier.A comprehensive echo parameter prediction model constructed by the random forest principle can predict the magnitude of short-time heavy precipitation 40-50 min in advance. Numerical simulation reveals that large amounts of water vapor existed in the near-surface atmosphere, and that the cells rapidly obtained moisture from the ambient atmosphere and developed rapidly through maternal feeding. The cold cloud zone was narrow, upright and had a high stretch height. The upward motion in clouds was strong and deep, and very rich in liquid water content. The graupel particles had a large vertical distribution range, the coexistence area of graupel and snow was large, the height of raindrops was close to the surface with a wide horizontal scale, and the precipitation efficiency was high. These may be the important elements responsible for the occurrence of the short-time heavy precipitation that exceeded historical extreme values. On the basis of the above analyses, a comprehensive parameter(CP) prediction model is worked out, which can estimate the developing trend of supercells and the intensity of short-time heavy precipitation about 1 h in advance.
文摘The microphysical structure of snow clouds and the growth process of snow crystals were observed by means of instrumented aircraft, weather radar, snow crystal observations etc. in Urumqi region during the winter of 1982. The analysis of three cases show that about 70% of snow mass growth is produced in the lower layer below 2000 m under the cold front, and that the concentration of ice crystals is as high as 60 L^(-1) and the supercooled water is absent in lower clouds. We may infer that the deposition of ice crystals and the aggregation of snow crystals are important processes for the snow development. The microphysical structure of the snow band near the front aloft and its characteristics as a seeder cloud are also described in this paper.
基金Supported by Bohai Rim Regional Science and Technology Collaborative Innovation Fund(QYXM202004)Hebei Provincial Science and Technology Plan(19275420D)"Cloud Precipitation Physics Aircraft Detection and Application Innovation Team"Project of Hebei Province Weather Modification Office.
文摘During the period of the super typhoon"Lekima"(No.1909)landed on the coast of North China,a high-resolution numerical simulation study was carried out with the WRF model on the clouds microphysical process of heavy precipitation.The results showed that(1)the water vapor convergence tended to develop and strengthen on the way forward of typhoon center,and the evolution of water vapor convergence zone was closely related to the development of typhoon asymmetric structure,and had a good corresponding relationship with the falling zone of the rainstorm.(2)The eastern coast of Hebei was located in the big-value area of water vapor transport belt in the northwest quadrant of the typhoon.Below 850 hPa,northeast wind appeared,and warm humid water vapor was transported from marine area to terrestrial by typhoon.Affected by upper-level westerly trough,westerly wind was dominated above 700 hPa,and water vapor convergence was transported from low level to upper level,and several rainstorm center appeared.(3)In the spiral rain bands of typhoon,the big-value center of graupel particles cooperated with the warm cloud enriched with water content,and the ground would produce a center of heavy precipitation,and the precipitation center of pure warm cloud appeared in 117.5°E.This phenomenon rarely occurred during continental cloud precipitation.Therefore,the contribution of warm cloud precipitation mechanism to the typhoon spiral rain belt should be emphasized.
基金National Natural Science Foundation of China(41675029)Postgraduate Research&Practice Innovation Program of Jiangsu Province(KYCX18_0998)+1 种基金Science and Technology Program of Huzhou(2021GZ14,2020GZ31)Science and Technology(Key)Program of Zhejiang Meteorological Service(2021ZD27)。
文摘To analyze the effects of gas cannons on clouds and precipitation,multisource observational data,including those from National Centers for Environmental Prediction(NCEP)reanalysis,Hangzhou and Huzhou new-generation weather radars,laser disdrometer,ground-based automatic weather station,wind profiler radar,and Lin'an C-band dualpolarization radar,were adopted in this study.Based on the variational dual-Doppler wind retrieval method and the polarimetric variables obtained by the dual-polarization radar,we analyzed the microphysical processes and the variations in the macro-and microphysical quantities in clouds from the perspective of the synoptic background before precipitation enhancement,the polarization echo characteristics before,during and after enhancement,and the evolution of the fine three-dimensional kinematic structure and the microphysical structure.The results show that the precipitation enhancement operation promoted the development of radar echoes and prolonged their duration,and both the horizontal and vertical wind speeds increased.The dual-polarization radar echo showed that the diameter of the precipitation particles increased,and the concentration of raindrops increased after precipitation enhancement.The raindrops were lifted to a height corresponding to 0 to-20℃due to vertical updrafts.Based on the disdrometer data during precipitation enhancement,the concentration of small raindrops(lgN_(w))showed a significant increase,and the mass-weighted diameter D_(m)value decreased,indicating that the precipitation enhancement operation played a certain“lubricating”effect.After the precipitation enhancement,the concentration of raindrops did not change much compared with that during the enhancement process,while the Dm increased,corresponding to an increase in rain intensity.The results suggest the positive effect of gas cannons on precipitation enhancement.
基金National Natural Science Foundation of China(41275043)Priority Academic Program Development of Jiangsu Higher Education Institutions(PAPD)
文摘In this study, the vertical profiles of radar refractive factor(Z) observed with an X-band Doppler radar in Jurong on July 13, 2012 in different periods of a stratiform cloud precipitation process were simulated using the Sim RAD software, and the contributions of each impact resulting in the bright band were analyzed quantitatively. In the simulation, the parameters inputted into Sim RAD were updated until the output Z profile was nearly consistent with the observation. The input parameters were then deemed to reflect real conditions of the cloud and precipitation. The results showed that a wider(narrower) and brighter(darker) bright band corresponded to a larger(smaller) amount, wider(narrower) vertical distribution, and larger(smaller) mean diameter of melting particles in the melting layer. Besides this,radar reflectivity factors under the wider(narrower) melting layer were larger(smaller). This may be contributed to the adequate growth of larger rain drops in the upper melting layer. Sensitivity experiments of the generation of the radar bright band showed that a drastic increasing of the complex refractive index due to melting led to the largest impact,making the radar reflectivity factor increase by about 15 d BZ. Fragmentation of large particles was the second most important influence, making the value decrease by 10 d BZ. The collision-coalescence between melting particles, volumetric shrinking due to melting, and the falling speed of raindrops made the radar reflectivity factor change by about 3-7d BZ. Shape transformation from spheres to oblate ellipsoids resulted in only a slight increase in the radar reflectivity factors(about 0.2 d BZ), which might be due to the fact that there are few large particles in stratiform cloud.
基金The National Key Basic Research Program of China under contract No.2014CB953904the Natural Science Foundation of Guangdong Province under contract No.2015A030311026the National Natural Science Foundation of China under contract Nos 41275145 and 41275060
文摘The weather research and forecasting（WRF） model is a new generation mesoscale numerical model with a fine grid resolution（2 km）, making it ideal to simulate the macro-and micro-physical processes and latent heating within Typhoon Molave（2009）. Simulations based on a single-moment, six-class microphysical scheme are shown to be reasonable, following verification of results for the typhoon track, wind intensity, precipitation pattern, as well as inner-core thermodynamic and dynamic structures. After calculating latent heating rate, it is concluded that the total latent heat is mainly derived from condensation below the zero degree isotherm, and from deposition above this isotherm. It is revealed that cloud microphysical processes related to graupel are the most important contributors to the total latent heat. Other important latent heat contributors in the simulated Typhoon Molave are condensation of cloud water, deposition of cloud ice, deposition of snow, initiation of cloud ice crystals, deposition of graupel, accretion of cloud water by graupel, evaporation of cloud water and rainwater,sublimation of snow, sublimation of graupel, melting of graupel, and sublimation of cloud ice. In essence, the simulated latent heat profile is similar to ones recorded by the Tropical Rainfall Measuring Mission, although specific values differ slightly.
文摘Cloud microphysical data observed with PMS probes have been combined with radar and other in-situ data collected by a NOAA P-3 aircraft that flew through the stratiform and transition regions of a mesoscale convective complex(MCC).The combined data have been analyzed with respect to the mescscale structure of the storm systems.The characteristics of ice particles in the transition and stratiform regions were quite differeat.The ice particle concentrations in the transition region were about 4 to 6 times that found in the stratiform region,and the size of ice particles in the stratiform region was about twice that in the transition region.The relatively lower radar reflectivity in the transition region is a result of smaller particle sizes.The main precipitation particle growth mechanisms are riming and aggregation in the transition region ard the aggregation process predominates in the stratiform region referred from the microphysical structures.The ag- gregation starts in the upper,colder levls but becomes more efficient as the particles approach the melting layer.
