Error Analysis And Modeling Of Precipitation Estimation For C-band Dual-polarization Radar

Dual-polarization Doppler weather radar can provide more parameters than conventional doppler weather radar,and has broad application potential in quantitative precipitation estimation.It is an important tool for short-term heavy rainfall monitoring and neighborhood prediction.However,the quantitative precipitation estimation accuracy of dual-polarization radar is affected by many factors.In order to better use dual-polarization radar to estimate precipitation and further improve the accuracy of precipitation estimation,error analysis and modeling of radar precipitation estimation are needed.This paper is based on the observation data of C-band Dual-linear Polarization Doppler weather radar(NUIST-CDP)of Nanjing University of Information Science and Technology during 2015 to 2016,combined with the OTT Parsivel raindrop spectrometer observation data of The Comprehensive observation base of Nanjing University of Information Science and Technology,SA weather radar data of Longwangshan mountain,and surface rainfall gauge data of Nanjing area.The error distribution of radar precipitation estimation is analyzed statistically,the representative error of rainfall gauge is separated,and the stochastic error and systematic error are quantitatively modeled.The main research is as follows:In the aspect of quality control of observation data of dual polarization radar,the accuracy of radar data is improved effectively through?andpreprocessing,attenuation correction,data screening,clutter identification and removal.In the study of quantitative precipitation estimation,rain drop spectrometer data were used to fit the rain measurement equation.By comparing the inversion results of_?,??,rain measurement formulas with the rain gauge,the estimation performance of each rain measurement formula was analyzed under different precipitation intensity.The results showed that,_and_,have better performance in light precipitation.When the rainfall threshold is greater than 2.5 mm/h,the advantage ofbecomes obvious.In the study of radar error,firstly,the spatial correlation function of rain gauge data is estimated,the gauge representative error caused by spatial mismatch between radar and rain gauge is calculated and separated,and the proportion of measurement error and parameter error in radar precipitation estimation error is analyzed.The gauge representative error of rain gauge caused by spatial mismatch should not be ignored.The point surface error should be eliminated when the radar resolution unit is large.Based on the attribute and distribution rule of radar precipitation estimation error,the quantitative models of random error and systematic error are established.The radar precipitation estimation error is modeled according to systematic error and random error,and it is found that the systematic error of radar precipitation near the surface is proportional to the rainfall intensity in a linear function form,and the double index model can better represent the random error distribution.Finally,based on the performance and error analysis of four rain measurement formulas,an optimized combination of dual polarization radar precipitation estimation algorithm is proposed.Based on the performance of different radar rain measurement formulas,the optimized combined precipitation algorithm is superior to the single rain measurement formula in accuracy and stability.