The Study Of Wind Field Retrieval By Double Radar And The Three Dimensional Structure Of Typhoon Precipitation Echo

Doppler weather radar is an important tool for monitoring and forewarning severe convective weather(strong wind,hail,tornado etc.).Bistatic(Multistatic)Doppler weather radar including a Doppler weather radar and one or more receiving equipment,is suitable for'building local strong weather detection network,which is a supplement for current weather radar network observation.Dual polarization Doppler weather radar is the enhanced version of Doppler weather radar.Bistatic radar and dual polarization radar play a unique role in the precipitation observation and research of weather radar.In this paper,the work,which focus on the method of the synthetic wind field inversion of bistatic Doppler radar,compute the radar meteorological equation of bistatic radar according to the scattering rule of precipitation target between the main station and passive station.Convergence,divergence,rotation,rising and sinking of wind field can be get through simulation experiment.We analyzed the charge of intensity of the typhoon and radial wind field echo features based on echo intensity and radial velocity data from two Doppler weather radars in Xiamen and Quanzhou.The "Meranti" typhoon wind distribution of the horizontal and vertical are effectively retrieved by three-dimensional wind field inversion equation with dual radar and dual polarization,providing abundant information for monitoring the detailed structure and evolution of typhoons.The analysis of typhoon "Meranti" was carried out by using the Xiamen S-band dual polarization Doppler radar.According to the moving path of the typhoon,the whole process is divided into different parts,namely the area near squall line front of typhoon,the spiral rain band region,the typhoon cloud wall and the eye of typhoon,respectively.The changes of polarization parameters and spatial distributions of the dominant water particles during the four parts of typhoon are shown in this paper.The results indicate that(1)There is a zero-level bright band around 5km on the RHI diagram.Under the bright band,a heavy rain is near to the center of typhoon,and the columnar echo represents moderate rain.The rest areas are small rain particles.There has small amount of supercooled water and wet snow near the bright band together with regular and irregular ice crystals on the bright belt.On the PPI map.the types of precipitation,corresponding to the four parts of the typhoon,are also different.(2)Convection developed exuberantly when it locates in the front of squall line near typhoon.The echo intensity,liquid water content and the diameter of precipitation particles are mostly largest near the typhoon center.The convection intensity closing to cloud wall is slightly higher than the echo top height of spiral rainband.(3)Statistical results of each polarization are shown as follows:these three polarization parameters,Zh,ZDR and ?HV are different in four parts and vertical directions of typhoon.The distribution of KDP values is not significant in vertical direction,but slightly different in each parts.Through the study on the polarization characteristics of the typhoon "Meranti",we have analyzed the microphysical structure of typhoon precipitation,and provided more reference information for the typhoon path,strength change and rainfall forecast.Finally,the comparation is done between the Xiamen dual polarization radar,Xiamen,Quanzhou and Zhangzhou Doppler weather radar.It is concluded that the average intensity,standard deviation and probability density distribution of echo intensity between of four radars are different with each other and change with height under different observation time.When the four radars worked together to analysis "Meranti”typhoon.It will be conducive to adjust and calibrate itself,more beneficial to realize the picture combination of radar network.