厦门市S波段双偏振雷达测雨效果分析

Analysis of Rainfall Measuring Errors of S-band Dual Polarization Weather Radar in Xiamen

选取2016年7月-2017年12月16次降水过程,利用厦门双偏振雷达的偏振参量资料及区域自动站小时雨强资料,统计分析不同降水强度下的偏振参量的值分布,并且对5种测雨方程的测雨效果及误差进行分析,主要得到以下结论:1)ZDR、Kdp只与粒子形状、取向和相态有关,随着雨强的增大,雨滴粒子增大,Zh、ZDR、Kdp总体趋势均是不断增大的,ρhv相差不大,基本在0.9以上;2)测雨方程R(Zh)、R(Zh,ZDR)的估测降水对实况降水严重低估,而方程R(Kdp,ZDR)会高估实况降水,方程R(Kdp)与R(Zh,Kdp,ZDR)的估测降水与实况降水最为接近;3)方程R(Zh)、R(Zh,ZDR)对小/中雨量级的降水估测效果较好,方程R(Kdp)、R(Kdp,ZDR)、R(Zh,Kdp,ZDR)对小/中雨量级及大雨量级的降水估测误差较大,而对暴雨以上量级降水的估测效果则有明显的改善,特别是方程R(Kdp);4)从5种测雨方程的稳定性来看,在小/中雨量级的降水中测雨方程的稳定性均较差,而在大雨以上量级的降水中稳定性明显改善,其中方程R(Zh)、R(Zh,ZDR)更加稳定一些,但与其他3组方程相差不大。

The Xiamen S-band dual polarization weather radar data and the hourly precipitation data from the regional automatic weather stations during 16 rainfall processes from July 2016 to November 2017 are used for the value distribution calculation of polarization parameters under different rainfall intensities and the analysis on effectiveness and errors of rainfall measuring by means of five radar rainfall estimation equations.The major conclusions are as follows:1)ZDR and Kdp are related to the shape,orientation and phase of raindrops.Zh,ZDR and Kdp are in an increasing trend in general with the increase of rainfall intensity and raindrop size.ρhv is over 0.9 basically,no clear differences.2)The estimated results of precipitation by the rainfall estimation equations R(Zh)and R(Zh,ZDR)are far below the observed precipitation.Conversely,the equation of R(Kdp,ZDR)tends to overestimate the actual situation.Only the equations of R(Kdp)and R(Zh,Kdp,ZDR)perform better in the estimating calculation of rains.3)The effects of equations R(Zh)and R(Zh,ZDR)are better in estimating light and moderate rains,while the equations R(Kdp),R(Kdp,ZDR)and R(Zh,Kdp,ZDR)perform poorly in estimating light,moderate and heavy rains,but their estimation to precipitation above the magnitude of rainstorm is outstanding,especially the equation R(Kdp).4)The stabilities of the five rainfall estimating equations are not so good for light and moderate rains,but get obviously improved for precipitation above the magnitude of heavy rain,of which the equations R(Zh)and R(Zh,ZDR)are more stable,with a little difference from the other three.