雨滴轴比订正对雷达参量及其关系的影响研究

利用Parsivel雨滴谱仪在山西祁县、介休两地2008年7、8月观测的数据资料,对比分析了两地的总雨滴谱样本特征和雷达参量的分布概率,研究了雨滴轴比订正对降雨率R、雨滴含水量W和反射率因子Z计算的影响,结果表明雨滴轴比对雷达参量影响不可忽略。雨滴轴比订正效果随着R的增大而增大,当R>5mm·h-1时,轴比订正效果明显,而因Z正比于尺度D的6次方,其订正效果更加明显。最后,在雨滴轴比订正基础上给出两地的Z-R关系,同时确定了未经过轴比订正的反射率因子Znoncorr与订正后的降雨率Rcorr之间的Znoncorr-Rcorr关系,以及反射率因子Z与雨水含量W的Z-W关系,为当地雷达定量测量降水、深入研究云降水形成的微物理过程和雷电对区域降水的影响等提供了科学依据。

Influence of the Raindrop Axis Ratio on Radar Parameters and Their Relationships

Based on the observational data of raindrop size distributions (DSDs) from Parsivel optical disdrometers in Qixian and Jiexiu of Shanxi Province during the period of July and August 2008, a contrast about the characteristics of DSDs and the statistical probability of radar parameters are provided. And then, the dependences of rainfall R and rainwater content W related with reflectivity Z upon axis ratio are discussed. It shows that as the rainfall (R) increases, the corrected R is improved, especially when R>5 mm·h-1. As reflectivity Z is proportional to the 6th power of diameter (D), the corrected reflectivity (Zcorr) is changed much more quickly. At last, on the basis of axis ratio, the Znoncorr-Rcorr relationship and the reflectivity Z and rainwater content W relationship (Z-W) offer a scientific ground for radar measurement of precipitation and a deep-going way research on cloud micro-physical processes and the effects of thunder-lightning on regional precipitation is determined.