Combining Mm5 And Mc Radiative Transfer Model Study On The Characteristics Of The Chinese Region Of Convective Precipitation Cloud Of Microwave Radiation

In this thesis the combination of NCAR/PennState Mesoscale Model Version5(MM5) and Monte-Carlo microwave radiation transfer model was used to study the relationship among the precipitation, microphysical characteristics of a convective cloud system and the upwelling radiance at pertinent microwave frequencies(85.5, 37.0 and 19.35GHz), as well as the microphysical structure of the precipitating system occurring over Chinese land region. The precipitation simulated by MM5 was compared with the observed rainfall rate, while the results of the model were preliminarily compared with TRMM products.The MM5 simulated a complete structure of a mesoscale convective cloud system over Chinese Mainland. The simulated rainfall rate of MM5 approached to the observed rain intensity. A comparison between microphysical characteristics derived from MM5 and the results from TRMM TMI products showed that MM5 gives a relatively realistic hydrometeor profiles. The hydrometeor information derived from the MM5 was then put into a 3-D microwave radiation transfer model that calculated the upwelling radiance received by the radiometer aboard the satellite. The relationship among the simulated brightness temperature (Tb), hydrometeor structure and surface rainfall rate indicated that the ice and snow hydrometeor at the top of the precipitating cloud significantly decrease the Tb at 85.5GHz due to scattering. The Tb is highly related to the density of the ice and snow particles. Since the convective cloud system is titled, and the viewing angle is oblique, the area displacement between ice hydrometeor and surface rainfall rate makes the relationship between Tb and surface rainfall rate be relatively small and so is the relationship between the Tb and the density of graupel particles. At the other two frequencies, the scattering influence of the ice hydrometeor and the emitting influence of the liquid hydrometeor were both strong. The relationship between Tb and surface rainfall rate is weak at 37.0GHz, and complex at 19.35GHz. The large graupel particle decreases the Tb significantly at 19.35GHz frequency, which means the information of Tb could instruct the rain drop density in the middle of the cloud when the emission of the background is changeless.