双线偏振雷达测雨公式优化方案的仿真研究

基于滴谱理论和散射原理,利用模拟的雨滴谱及其反演的雷达偏振参数,讨论双线偏振雷达参数随雨滴谱变化而变化的规律;并提出一种测雨公式的优化改进方案。在不同的差分反射率因子Z_(DR)取值区间内,统计相应的测雨公式系数。同时,提出了3种Z_(DR)区间划分的方法:1利用统计学中的t检验法检测测雨公式系数随Z_(DR)变化而变化的曲线图中的显著突变点;并将这些点对应的Z_(DR)值作为区间划分的临界值。2直接按一定的步长等间距地将Z_(DR)的范围划分为不同区间。3依托于Z_(DR)与中值体积直径D_0的拟合关系,通过对D_0的取值范围等步长划分而间接得到相应的Z_(DR)的范围。在对方法二、三最优等分步长进行讨论的基础上,利用模拟的雨滴谱对上述方法进行检验;并对检验效果逐一进行对比分析。结果表明这三种分级统计方法的效果较未进行分级统计,直接采用固定系数测雨公式估测降水的计算结果更加精确,误差有明显改善。

SimulationSresearchSonStheSoptimizationSschemeSofStheSprecipitationSmeasurementSformulaSofSDual-linearSPolarizationSRadar

Based on the raindrop spectrum and scattering theory, using simulated raindrop spectrum and its polarization radar parameters to discussed the changing laws of the radar parameters with raindrop spectrum, in order to mention a improved scheme of precipitation formula: measuring precipitation coefficients using three different interval statistic methods of differential reflectivity (ZDR). The first method using statistical t test to detect the precipitation coefficient with the change of ZDR, discover the points of marked mutation, and use these points to divide ZDR; the second method is to Divide ZDR according to a specific step; the third method based on the fitting relationship between the median volume diameter and ZDR in order to divide ZDR through D0. Then use the simulated raindrop spectrum to analysis the three methods, and compare the results. The results show that the effect of these three methods is more accurate than using valid precipitation coefficients to estimate raindrop.