| Weining is located in the Wumeng Mountains in the eastern part of the Yunnan-Guizhou Plateau,with complex terrain and a large altitude gradient.Weining is an important tobacco planting area in Guizhou Province.Hail disasters often cause significant economic losses in Weining and affect economic development.The text uses hail data to classify and analyze the circulation characteristics of 30 hailstorm days from2018 to 2019,and uses meteorological and statistical methods to divide the hailstorm process into plateau troughs,south branch troughs,and 500 h Pa circulation characteristics.The sub-high type three types of weather conditions prone to hailstorm processes.Using NECP(National Centers for Environmental Prediction)reanalysis data,radar echo data,to analyze the environmental conditions,convection structure,and convective maintenance development characteristics of different weather-type hailstorm processes,to understand the characteristics of the changes from hailstorms to strong hailstorms Various physical quantities are used to quantitatively describe the characteristics of different weather hailstorms.Aiming at the plateau trough hailstorm process,by understanding its trigger maintenance mechanism,thermodynamic and water vapor condition characteristics,and monomer interaction,the relevant physical quantity thresholds are worthwhile to come up with a diagnostic method for Weining severe hailstorm hailstorm process.In order to better apply this diagnostic method to actual forecasting and early warning work,a multi-index stacking method,multiple stepwise regression method combined with a representative series of forecasting factors were used to construct a forecasting model for Weining area.The main research contents are as follows:(1)According to the main impact system of 500 h Pa,the Weining hailstorm process can be divided into three typical weather types:plateau trough type,southern branch trough type,and subtropical high type.Under different weather configurations,the conditions that promote the development of strong convective weather are different,and the water vapor and convergence uplift conditions are different.Use?se,water vapor vertical helicity,vertical speed,etc.to understand the differences in water vapor,convergent uplift,and unstable environmental conditions in various hailstorm processes,as well as understand the ability of various physical quantities to identify various hailstorm processes,so as to use each physical quantity to distinguish different The weather hailstorm process is quantitatively described.(2)When using radar echoes to diagnose hailstorm development characteristics,the combined reflectivity and radial velocity are used to classify and analyze the hailstorm development and the hailstorm process.The development process of hailstorms was studied in stages,the development characteristics of various hailstorms were analyzed,and the differences in echo characteristics of various hailstorm processes were understood.Identify the process of severe hailstorm with the relationship between 0?height and strong echo.(3)For the maintenance and development of the hailstorm process and the development of the severe hailstorm process;use the thermal shear advection parameters and echo characteristics to analyze the maintenance development characteristics,and understand that the three types of hailstorm process often occur strong wind shear and single merger promotion The phenomenon of hailstorm development,and the difference in the maintenance and development of various hailstorm processes.According to its characteristics and differences,a representative physical quantity is selected to quantitatively describe its characteristic differences,which provides a certain reference for building a hailstorm forecast model.(4)Due to the difference in the occurrence and development characteristics of various types of hailstorm processes,according to the characteristics of convective development of the hailstorm process of the plateau trough type,the circulation situation analysis combined with various physical quantities is used to determine the hailstorm and strong hailstorm processes.First,after determining the background of the plateau trough circulation,according to the large value center of the wet heat vertical helicity greater than 0.8×10-1?m3?k?kg-1?s-2 and the vertical helicity of water vapor greater than 0.8×10-5m?s-1 and the hailfall area can preliminarily determine the hail potential of strong convective movement.After judging the potential for hail reduction,combined with the development of the abnormal value of the wet potential vortex and the gradient development,the overall impact of the overall environmental conditions on the strong convection was diagnosed,and the maintenance of the hail potential was more conveniently and quickly monitored.After confirming that the potential for hail reduction continues to develop,if a case meets the threshold value of thermal shear advection parameters or the threshold of the relationship between the 45 d BZ echo top height and the 0?height layer,then the case is determined to be a hailstorm developing into a single hailstorm.(5)In order to make this forecasting method more widely used in actual forecasting and early warning work,a forecasting method for plateau trough hailstorm process is constructed by using multi-index superposition method and multiple stepwise regression method.The multi-index method analysis shows that 2 to 4 forecast factors have higher accuracy.Two or more forecasting factors were selected to construct a regression forecasting equation system for the plateau trough hailstorm process using multiple stepwise regression method.A multiple stepwise regression equation composed of SI index and vertical helicity of water vapor is obtained,with 0.6 to 0.8 as the predicted value range.This method greatly improves the accuracy of hailstorm forecast and reduces the false alarm rate. |
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