雷达回波强度与雨滴谱参数的相关性研究

摘要

At present,the correlation between radar echo intensity and rain intensity is mostly adopted in radar quantitative precipitation estimation,but radar echo intensity does not correspond to rain intensity.The radar observations and synergetic Parsivel raindrop size distribution data from Lushan and Nanjing were used to establish the functional relations between radar echo intensity and various raindrop size distribution parameters.At the same time,the radar echo intensities fitted by the determinate func tional relations were compared to the real radar echo intensities in order to check the rationality of the assumed functional relations.And the optimal option about y in the functional relation was obtained by comparing the fitting relative errors of two types of clouds precipitation in two places.All the work above is done to find a new approach for radar quantitative precipitation estimation.The results prove that the fitting of raindrop size distribution parameters of two types of clouds precipitation in Lushan and Nanjing to radar echo intensity is generally good,and the fitting of convective cloud precipitation is significantly bet ter than that of stratiform cloud precipitation.The fitting curve of each raindrop size distribution parameter to radar echo intensity in the stratiform cloud precipitation is roughly similar,but those fitting curves in the convective cloud precipitation are quite different in two places.The relative errors fitted by two types of clouds precipitation in Nanjing are smaller than those in Lushan.Except for convective cloud precipitation in Lushan,Dv is the optimal option about y in the fitting formulas of two types of clouds precipitation in two places.And the fitting of N and DP is the best in the fitting formula of convective cloud precipitation in Lushan.%在雷达定量探测降水方面,目前大都采用雷达回波强度与降水强度的相关性来定量估算,但雷达回波强度与降水强度并非一一对应.本文利用从庐山和南京收集到的雷达观测资料和同步Parsivel观测到的雨滴谱数据,建立雷达回波强度与不同雨滴谱参数的函数关系,将由确定的函数关系式拟合后的雷达回波强度与雷达实测的回波强度作对比,以检验假定函数关系式的合理性,同时通过对比两地两类云降水拟合值的相对误差,给出了函数关系式中的最优y选项,为雷达定量估算降水量寻找新的途径.研究结果表明:庐山和南京两地两类云降水的雨滴谱参数对雷达回波强度的拟合普遍较好,其中对流云降水的拟合都明显好于层状云降水.两地层状云降水中各个雨滴谱参数对雷达回波强度的拟合曲线都大体相近,而对流云降水中,不同雨滴谱参数对雷达回波强度的拟合曲线差异较大.南京两类云降水拟合的相对误差要小于庐山两类云降水拟合的相对误差.除庐山对流云降水外,Dv是两地两类云降水拟合公式中最优的y选项.而庐山对流云降水拟合式中,以N和DP的拟合最佳.