Atmospheric Structure Of Rainstorm And Characteristic Analysis Of Dual Polarization Radar Parameters

Torrential rain is one of the most important meteorological disasters in our country,which is very harmful to the national economy and people's life.Because the formation mechanism and evolution process of rainstorm are very complex,it is very difficult for the traditional forecasting method to accurately predict the rainstorm,especially the sudden rainstorm.Its structural characteristics still exist a lot of mechanism which is not perfect.Dual polarization Doppler weather radar is a new generation weather radar which will be upgraded in China in the coming 3-5 years..It can transmit and accept two kinds of polarization waves,both horizontal and vertical.It can not only obtain the parameters of single polarization radar,but also obtain more double polarization parameters.Through inverse analysis,the shape and size of precipitation particles can be obtained and more detailed information,such as particle concentration and phase distribution,is beneficial to the further study of cloud and precipitation physics.In short-term prediction,disaster prevention and mitigation,the dual polarization Doppler weather radar will play a greater application value.In this paper,the change mechanism of atmospheric structure of rainstorm is concerned.By using sounding data,double polarization Doppler weather radar data and infrared satellite data,the atmospheric structure of several rainstorm events and the characteristics of dual polarization radar parameters are studied.In particular,a new understanding of the formation mechanism of sudden rainstorm has been made from the angle of atmospheric chemistry.The main conclusions are as follows.1.Different bipolarization parameters show different characteristics for precipitation events,for example,the difference reflectivity factor Zdr has a good correspondence with precipitation intensity,and the correlation coefficient ? hv is more sensitive to the recognition of fusion layer.The differential propagation phase shift rate(KDP)is better for the difference degree of rainstorm.The characteristics of rainstorm and the evolution of atmospheric structure can be further understood by combining the characteristics of various bipolarization parameters.2.The change of methane content has an important effect on atmospheric stability.Due to the chemical properties of methane and the photochemical reaction occurring in the troposphere,when the methane content changes dramatically,the methane content rapidly rises to a maximum and rapidly decreases to a minimum value,the phenomenon of ultra-low temperature may occur in the middle and upper troposphere.The vertical structure of the atmosphere becomes the unstable structure of upper cooling and warm,and becomes an important condition to trigger the severe convective weather.In this case,it is possible to cause sudden rainstorm if it is combined with the suitable water vapor condition and the circulation background field.3.Typhoon will cause local strong convective weather,large-scale rainstorm and even generate tornadoes and other disasters.Typhoon spiral rain belt is an important mesoscale system of typhoon,which often brings strong vertical motion and condensation latent heat release.With the wide use of dual polarization Doppler radar,various dual polarization parameters can better reflect the structure of convection cell inside typhoon.It provides a better basis for the study of typhoon rainstorm and mesoscale weather system.