An extreme torrential rain(ETR)event occurred in Henan Province,China,during 18-21 July 2021.Based on hourly rain-gauge observations and ERA5 reanalysis data,the ETR was studied from the perspective of kinetic energy(...An extreme torrential rain(ETR)event occurred in Henan Province,China,during 18-21 July 2021.Based on hourly rain-gauge observations and ERA5 reanalysis data,the ETR was studied from the perspective of kinetic energy(K),which can be divided into rotational wind(V_(R))kinetic energy(K_(R)),divergent wind kinetic energy(K_(D)),and the kinetic energy of the interaction between the divergent and rotational winds(K_(RD)).According to the hourly precipitation intensity variability,the ETR process was divided into an initial stage,a rapid increase stage,and maintenance stage.Results showed that the intensification and maintenance of ETR were closely related to the upper-level K,and most closely related to the upperlevel K_(R),with a correlation coefficient of up to 0.9.In particular,the peak value of hourly rainfall intensity lagged behind the K_(R) by 8 h.Furthermore,diagnosis showed that K transformation from unresolvable to resolvable scales made the ETR increase slowly.The meridional rotational wind(u_(R))and meridional gradient of the geopotential(φ)jointly determined the conversion of available potential energy(APE)to K_(R) through the barotropic process,which dominated the rapid enhancement of K_(R) and then caused the rapid increase in ETR.The transportation of K by rotational wind consumed K_(R),and basically offset the K_(R) produced by the barotropic process,which basically kept K_(R) stable at a high value,thus maintaining the ETR.展开更多
We analyzed cloud microphysical processes' latent heat characteristics and their influence on an autumn heavy rain event over Hainan Island,China,using the mesoscale numerical model WRF and WRF-3DVAR system.We fou...We analyzed cloud microphysical processes' latent heat characteristics and their influence on an autumn heavy rain event over Hainan Island,China,using the mesoscale numerical model WRF and WRF-3DVAR system.We found that positive latent heat occurred far above the zero layer,while negative latent heat occurred mainly under the zero layer.There was substantially more positive latent heat than negative latent heat,and the condensation heating had the most important contribution to the latent heat increase.The processes of deposition,congelation,melting and evaporation were all characterized by weakening after their intensification;however,the variations in condensation and sublimation processes were relatively small.The main cloud microphysical processes for positive latent heat were condensation of water vapor into cloud water,the condensation of rain,and the deposition increase of cloud ice,snow and graupel.The main cloud microphysical processes for negative latent heat were the evaporation of rain,the melting and enhanced melting of graupel.The latent heat releases due to different cloud microphysical processes have a significant impact on the intensity of precipitation.Without the condensation and evaporation of rain,the total latent heating would decrease and the moisture variables and precipitation would reduce significantly.Without deposition and sublimation,the heating in high levels would decrease and the precipitation would reduce.Without congelation and melting,the latent heating would enhance in the low levels,and the precipitation would reduce.展开更多
[Objective] The research aimed to analyze a turning weather process in Binzhou City of Shandong Province in midsummer of 2010.[Method] Started from the short-term forecast ideas,the formation reason of heavy or torren...[Objective] The research aimed to analyze a turning weather process in Binzhou City of Shandong Province in midsummer of 2010.[Method] Started from the short-term forecast ideas,the formation reason of heavy or torrential rain and local heavy rainstorm in Binzhou City during 4-5 August,2010 was analyzed from the circulation situation,physical quantity field,radar echo and so on.[Result] The westerly trough and cold air were the trigger mechanisms of precipitation.The warm wet air flow at the edge of subtropical high and the high-altitude low trough were the main systems of precipitation.It was the typical precipitation process that the northwest of subtropical high overlapped with the westerly trough.In the prior period,the high temperature continued.The cold air at 500 hPa made the convection strengthen.It was the main reason that the local precipitation was strong.In the forecast of rainstorm,the specific humidity,K index and SI index were the good physical quantities and reference indexes.In the formation process of rainstorm,K index had the increasing process.When the rainstorm finished,or the rain intensity weakened,K index decreased obviously.SI index indicated the development of convective precipitation.The radar echo analysis found that the mesocyclone appeared in the process for a short time.For it weakened quickly and disappeared in the shift process,the strong precipitation and gale were formed in the west of Binzou,but the hail wasn’t generated.[Conclusion] The research provided the experience for the forecast of such weather in future.展开更多
A shower cloud observed in Jiangxi,a hailstorm observed in Hebei and“75.8”torrential rain in Henan are simulated with our microphysical model in a one-dimensional framework.The model,using the radio- sonde data as i...A shower cloud observed in Jiangxi,a hailstorm observed in Hebei and“75.8”torrential rain in Henan are simulated with our microphysical model in a one-dimensional framework.The model,using the radio- sonde data as input,gets its output which shows agreement in many aspects as compared with observations in each case.The glaciation of small cumulus cloud,low precipitation efficiency of hailstorm and the per- sistence of torrential rain are demonstrated.It is also shown that the Bergeron process has little influence, but the warm-rain process plays an important role in the formation of precipitation in cumulonimbus with a warm cloud base.展开更多
In this paper the Morlet complex wavelet {unction was applied to analyze the evolution features of multi-scale wave-intensity during a torrential rain process.Separating the suhsynoptic scale system on temperature of ...In this paper the Morlet complex wavelet {unction was applied to analyze the evolution features of multi-scale wave-intensity during a torrential rain process.Separating the suhsynoptic scale system on temperature of black body (TBB) fields during a torrential rain process over the Middle and Lower Reaches of Changjiang River in the last dekad of July 1998,the evolution of multi-scale wave-intensity can be expressed by wavelet modules,and its coherence was investigated with the cross spectrum between the multi-scale waves.The results show that the process of the accumulation and release on the energy of meso-β scale system was shown in the torrential rain process,and the meso-α scale system had an interference effect on the meso-β system in a shorter period.展开更多
The heaviest rainfall over 61 yr hit Beijing during 21-22 July 2012.Characterized by great rainfall amount and intensity,wide range,and high impact,this record-breaking heavy rainfall caused dozens of deaths and exten...The heaviest rainfall over 61 yr hit Beijing during 21-22 July 2012.Characterized by great rainfall amount and intensity,wide range,and high impact,this record-breaking heavy rainfall caused dozens of deaths and extensive damage.Despite favorable synoptic conditions,operational forecasts underestimated the precipitation amount and were late at predicting the rainfall start time.To gain a better understanding of the performance of mesoscale models,verification of high-resolution forecasts and analyses from the WRFbased BJ-RUCv2.0 model with a horizontal grid spacing of 3 km is carried out.The results show that water vapor is very rich and a quasi-linear precipitation system produces a rather concentrated rain area.Moreover,model forecasts are first verified statistically using equitable threat score and BIAS score.The BJ-RUCv2.0forecasts under-predict the rainfall with southwestward displacement error and time delay of the extreme precipitation.Further quantitative analysis based on the contiguous rain area method indicates that major errors for total precipitation(〉 5 mm h^(-1)) are due to inaccurate precipitation location and pattern,while forecast errors for heavy rainfall(〉 20 mm h^(-1)) mainly come from precipitation intensity.Finally,the possible causes for the poor model performance are discussed through diagnosing large-scale circulation and physical parameters(water vapor flux and instability conditions) of the BJ-RUCv2.0 model output.展开更多
A heavy rainfall in the Meiyu front during 4-5 July 2003 is simulated by use of the non-hydrostatic mesoscale model MM5 (V3-6) with different explicit cloud microphysical parameterization schemes. The characteristic...A heavy rainfall in the Meiyu front during 4-5 July 2003 is simulated by use of the non-hydrostatic mesoscale model MM5 (V3-6) with different explicit cloud microphysical parameterization schemes. The characteristics of microphysical process of convective cloud are studied by the model outputs. The simulation study reveals that: (1) The mesoscale model MM5 with explicit cloud microphysical process is capable of simulating the instant heavy rainfall in the Meiyu front, the rainfall simulation could be improved signifi- cantly as the model resolution is increased, and the Goddard scheme is better than the Reisner or Schultz scheme. (2) The convective cloud in the Meiyu front has a comprehensive structure composed of solid, liquid and vapor phases of water, the mass density of water vapor is the largest one in the cloud; the next one is graupel, while those of ice, snow, rain water and the cloud water are almost same. The height at which mass density peaks for different hydrometeors is almost unchangeable during the heavy rainfall period. The mass density variation of rain water, ice, and graupel are consistent with that of ground precipitation, while that of water vapor in the low levels is 1-2 h earlier than the precipitation. (3) The main contribution to the water vapor budget in the atmosphere is the convergence of vapor flux through advection and convection, which provides the main vapor source of the rainfall. Besides the basic process of the auto-conversion of cloud water to rain water, there is an additional cloud microphysical process that is essential to the formation of instant heavy rainfall, the ice-phase crystals are transformed into graupels first and then the increased graupels mix with cloud water and accelerates the conversion of cloud water to rain water. The positive feedback mechanism between latent heat release and convection is the main cause to maintain and develop the heavy precipitation.展开更多
基金jointly supported by the National Natural Science Foundation of China(Grant Nos.42275013,42030611 and 42175008)the Open Grants of the State Key Laboratory of Severe Weather(Grant No.2021LASWB17)。
文摘An extreme torrential rain(ETR)event occurred in Henan Province,China,during 18-21 July 2021.Based on hourly rain-gauge observations and ERA5 reanalysis data,the ETR was studied from the perspective of kinetic energy(K),which can be divided into rotational wind(V_(R))kinetic energy(K_(R)),divergent wind kinetic energy(K_(D)),and the kinetic energy of the interaction between the divergent and rotational winds(K_(RD)).According to the hourly precipitation intensity variability,the ETR process was divided into an initial stage,a rapid increase stage,and maintenance stage.Results showed that the intensification and maintenance of ETR were closely related to the upper-level K,and most closely related to the upperlevel K_(R),with a correlation coefficient of up to 0.9.In particular,the peak value of hourly rainfall intensity lagged behind the K_(R) by 8 h.Furthermore,diagnosis showed that K transformation from unresolvable to resolvable scales made the ETR increase slowly.The meridional rotational wind(u_(R))and meridional gradient of the geopotential(φ)jointly determined the conversion of available potential energy(APE)to K_(R) through the barotropic process,which dominated the rapid enhancement of K_(R) and then caused the rapid increase in ETR.The transportation of K by rotational wind consumed K_(R),and basically offset the K_(R) produced by the barotropic process,which basically kept K_(R) stable at a high value,thus maintaining the ETR.
基金National Natural Science Foundation of China(41275060)National Natural Science Foundation of China(41275145)+1 种基金National Key Basic Research Program of China(2014CB953903)Fundamental Research Funds for the Central Universities(131gjc03)
文摘We analyzed cloud microphysical processes' latent heat characteristics and their influence on an autumn heavy rain event over Hainan Island,China,using the mesoscale numerical model WRF and WRF-3DVAR system.We found that positive latent heat occurred far above the zero layer,while negative latent heat occurred mainly under the zero layer.There was substantially more positive latent heat than negative latent heat,and the condensation heating had the most important contribution to the latent heat increase.The processes of deposition,congelation,melting and evaporation were all characterized by weakening after their intensification;however,the variations in condensation and sublimation processes were relatively small.The main cloud microphysical processes for positive latent heat were condensation of water vapor into cloud water,the condensation of rain,and the deposition increase of cloud ice,snow and graupel.The main cloud microphysical processes for negative latent heat were the evaporation of rain,the melting and enhanced melting of graupel.The latent heat releases due to different cloud microphysical processes have a significant impact on the intensity of precipitation.Without the condensation and evaporation of rain,the total latent heating would decrease and the moisture variables and precipitation would reduce significantly.Without deposition and sublimation,the heating in high levels would decrease and the precipitation would reduce.Without congelation and melting,the latent heating would enhance in the low levels,and the precipitation would reduce.
文摘[Objective] The research aimed to analyze a turning weather process in Binzhou City of Shandong Province in midsummer of 2010.[Method] Started from the short-term forecast ideas,the formation reason of heavy or torrential rain and local heavy rainstorm in Binzhou City during 4-5 August,2010 was analyzed from the circulation situation,physical quantity field,radar echo and so on.[Result] The westerly trough and cold air were the trigger mechanisms of precipitation.The warm wet air flow at the edge of subtropical high and the high-altitude low trough were the main systems of precipitation.It was the typical precipitation process that the northwest of subtropical high overlapped with the westerly trough.In the prior period,the high temperature continued.The cold air at 500 hPa made the convection strengthen.It was the main reason that the local precipitation was strong.In the forecast of rainstorm,the specific humidity,K index and SI index were the good physical quantities and reference indexes.In the formation process of rainstorm,K index had the increasing process.When the rainstorm finished,or the rain intensity weakened,K index decreased obviously.SI index indicated the development of convective precipitation.The radar echo analysis found that the mesocyclone appeared in the process for a short time.For it weakened quickly and disappeared in the shift process,the strong precipitation and gale were formed in the west of Binzou,but the hail wasn’t generated.[Conclusion] The research provided the experience for the forecast of such weather in future.
文摘A shower cloud observed in Jiangxi,a hailstorm observed in Hebei and“75.8”torrential rain in Henan are simulated with our microphysical model in a one-dimensional framework.The model,using the radio- sonde data as input,gets its output which shows agreement in many aspects as compared with observations in each case.The glaciation of small cumulus cloud,low precipitation efficiency of hailstorm and the per- sistence of torrential rain are demonstrated.It is also shown that the Bergeron process has little influence, but the warm-rain process plays an important role in the formation of precipitation in cumulonimbus with a warm cloud base.
基金Supported by the National Key Program for Developing Basic Science(G1998040907)
文摘In this paper the Morlet complex wavelet {unction was applied to analyze the evolution features of multi-scale wave-intensity during a torrential rain process.Separating the suhsynoptic scale system on temperature of black body (TBB) fields during a torrential rain process over the Middle and Lower Reaches of Changjiang River in the last dekad of July 1998,the evolution of multi-scale wave-intensity can be expressed by wavelet modules,and its coherence was investigated with the cross spectrum between the multi-scale waves.The results show that the process of the accumulation and release on the energy of meso-β scale system was shown in the torrential rain process,and the meso-α scale system had an interference effect on the meso-β system in a shorter period.
基金Supported by the National(Key)Basic Research and Development(973)Program of China(2013CB430106)China Meteorological Administration Special Public Welfare Research Fund(GYHY201206005)+1 种基金National Natural Science Foundation of China(41175087)National Fund for Fostering Talents(J1103410)
文摘The heaviest rainfall over 61 yr hit Beijing during 21-22 July 2012.Characterized by great rainfall amount and intensity,wide range,and high impact,this record-breaking heavy rainfall caused dozens of deaths and extensive damage.Despite favorable synoptic conditions,operational forecasts underestimated the precipitation amount and were late at predicting the rainfall start time.To gain a better understanding of the performance of mesoscale models,verification of high-resolution forecasts and analyses from the WRFbased BJ-RUCv2.0 model with a horizontal grid spacing of 3 km is carried out.The results show that water vapor is very rich and a quasi-linear precipitation system produces a rather concentrated rain area.Moreover,model forecasts are first verified statistically using equitable threat score and BIAS score.The BJ-RUCv2.0forecasts under-predict the rainfall with southwestward displacement error and time delay of the extreme precipitation.Further quantitative analysis based on the contiguous rain area method indicates that major errors for total precipitation(〉 5 mm h^(-1)) are due to inaccurate precipitation location and pattern,while forecast errors for heavy rainfall(〉 20 mm h^(-1)) mainly come from precipitation intensity.Finally,the possible causes for the poor model performance are discussed through diagnosing large-scale circulation and physical parameters(water vapor flux and instability conditions) of the BJ-RUCv2.0 model output.
基金Supported by the National Basic Research Program of China under Grant No.2006CB400505the National Natural Science Foundation of China under Grant No.40675040.
文摘A heavy rainfall in the Meiyu front during 4-5 July 2003 is simulated by use of the non-hydrostatic mesoscale model MM5 (V3-6) with different explicit cloud microphysical parameterization schemes. The characteristics of microphysical process of convective cloud are studied by the model outputs. The simulation study reveals that: (1) The mesoscale model MM5 with explicit cloud microphysical process is capable of simulating the instant heavy rainfall in the Meiyu front, the rainfall simulation could be improved signifi- cantly as the model resolution is increased, and the Goddard scheme is better than the Reisner or Schultz scheme. (2) The convective cloud in the Meiyu front has a comprehensive structure composed of solid, liquid and vapor phases of water, the mass density of water vapor is the largest one in the cloud; the next one is graupel, while those of ice, snow, rain water and the cloud water are almost same. The height at which mass density peaks for different hydrometeors is almost unchangeable during the heavy rainfall period. The mass density variation of rain water, ice, and graupel are consistent with that of ground precipitation, while that of water vapor in the low levels is 1-2 h earlier than the precipitation. (3) The main contribution to the water vapor budget in the atmosphere is the convergence of vapor flux through advection and convection, which provides the main vapor source of the rainfall. Besides the basic process of the auto-conversion of cloud water to rain water, there is an additional cloud microphysical process that is essential to the formation of instant heavy rainfall, the ice-phase crystals are transformed into graupels first and then the increased graupels mix with cloud water and accelerates the conversion of cloud water to rain water. The positive feedback mechanism between latent heat release and convection is the main cause to maintain and develop the heavy precipitation.