风廓线雷达探测降水云体中雨滴谱的试验研究

A Study of Drop-Size Distribution in Precipitation Cloud from Wind Profile Radar

对风廓线雷达探测降水时出现的双峰型功率谱密度分布的回波,进行大气返回信号和降水返回信号的剥离,由大气返回信号求出环境大气的垂直运动,导出降水质点下降末速度的功率谱密度分布,进而求出云体中的雨滴谱分布。对两次降水进行了雨滴谱反演试验,提取了不同高度上30多份雨滴谱分布,雨滴谱分布基本上呈现出指数分布形式。指数拟合后求出雨滴谱的浓度参数N0由几百到几千m-3mm-1,尺度参数λ为3.8～4.5 mm-1。试验中,还由反演的雨滴谱估算出云中含水量,得出降水云体中含水量随高度的分布,与附近多普勒天气雷达观测进行了比较。风廓线雷达与多普勒天气雷达探测到的回波强度随高度分布基本一致,云中含水量估算的均值基本相同,而风廓线雷达由雨滴谱估算出的含水量随高度分布可以反映出雨滴谱变化的影响,随高度分布更为精细。

Using the wind profile radar to detect precipitation,it would appear the bimodal-shaped power spectral density distribution.By means of stripping the atmospheric return signal and the precipitation return signal,the vertical motion of atmospheric environment with the atmospheric return signal,exported the distribution of power spectral density of final velocity of precipitation particle are evaluated,and then the raindrop spectrum in the clouds is evaluated.Through the raindrop spectrum inversion test in twice precipitation processes,the more than 30 raindrop size distributions are extracted at different heights,the raindrop size distribution basically show the form of exponential distribution.The concentration parameters of raindrop size distribution,N0,ranges from several hundreds to several thousands mm-1 ·m-3,and λ,a scale parameter,sits around 3.8~4.5 mm-1. In the experiment,the water content of clouds with the inversion of raindrop size distribution is also evaluated,the distribution of water content with height in the body of precipitation cloud is derived,comparing with Doppler weather radar nearby.The distributions of echo intensity with height detected by wind profiler radar and Doppler weather radar are close,and the mean estimates of cloud water content are also basical the same,but the distribution with heights are more elaborate.The distributions of water content with height evaluated by wind profile radar have some fluctuation,which may be influenced by raindrop spectrum.