Precipition Retrieval Of Dual-Band Radar

Precipitation is very common in human daily life,which has an important impact on radar communication and meteorological observation.In order to ensure the transmission effect of radar communication and the accuracy of meteorological observation,it is particularly important to study the scattering attenuation of precipitation and analyze the precipitation types.As precipitation particles are mainly divided into rain droplets and ice crystals,the main research in this paper is also aimed at these two kinds of particles.The main research results of this paper include:1.The scattering characteristics of small particles are analyzed by Rayleigh and Mie scattering.Mie scattering and discrete dipole approximation(DDA)methods are used to analyze the scattering characteristics of particles whose size is close to wavelength.The comparison results show the accuracy and availability of the DDA approximation method in calculating the scattering characteristics of particles.Subsequently,the raindrop particle model and ice crystal particle model are given.The scattering characteristics of the two models are studied by discrete dipole approximation(DDA).2.Based on the scattering characteristics of raindrop particles and ice particles in the X band and Ka band,different retrieval formulas are established by using ITU-R attenuation model,and the error of retrieval by attenuation is illustrated by comparing with empirical formulas.Based on the radar equation and the backscattering factor of particles,the formulas between the radar reflectivity factor(radar reflectivity)and precipitation rate,rainfall rate in X band and Ka band have been established in this paper.The accuracy of the formula is illustrated by comparison with empirical formula and data.3.In order to improve the accuracy of precipitation retrieval.Two methods of two-factor for retrieving precipitation are presented in this paper: one is to use the same band's characteristic attenuation and radar reflectivity to retrieve precipitation;the other is to use dual band radar reflectivity and its ratio to retrieve precipitation.In the range of data collected in this paper,the accuracy of two-factor retrieval for precipitation is greatly improved.4.This paper combines the fuzzy logic algorithm,radar reflectivity and characteristic attenuation of dual-band radar to classify precipitation types.The classification results show the general accuracy of the fuzzy logic classification method in the classification of precipitation types.However,for some special inputs,the classification results are not unique,so this paper uses the neural network algorithm to modify and adjust the membership function parameters.The results of the adjusted neural network-fuzzy logic classification system are more accurate and unique,which improves the accuracy of precipitation classification.