3mm多普勒云雷达测量反演云内空气垂直速度的研究

A Case Study of Deriving Vertical Air Velocity from 3-mm Cloud Radar

垂直指向的W-波段大气云雷达(WACR)不仅测量云粒子的反射率因子Z,而且测量多普勒速度谱。本文利用寿县气象站WACR在2008年11月1日一个时段的测量,进行云内空气垂直速度反演试验。首先讨论个例中反射率、Doppler平均速度及谱宽的分布特征及原因,然后利用小粒子示踪法和改进的以小粒子示踪法为基础的粒子下降速度w0—反射率因子(w0-Z)关系法反演了云内空气垂直速度,进而结合Doppler谱数据分析反演结果。结果显示:小粒子示踪法在湍流较弱时能比较精确地反演空气垂直速度,而湍流较强时,湍流造成的误差不可忽略;改进算法在湍流较强时能够减少湍流对反演结果的影响。

The vertically pointing cloud radar（WACR） can measure not only the reflectivity of cloud particles but also Doppler spectra.Retrieval of vertical air motions in cloud is demonstrated using measurements by WACR at Shouxian site during a period of 1 November 2008.The distribution characteristics of reflectivity,Doppler mean velocity,and spectral width are initially discussed.Retrieval of vertical air motions is demonstrated by the liquid droplets trace method and the improved w0-Z relationship method which is based on the liquid droplets trace method.The results are comparatively analysed with Doppler spectra.The liquid droplets trace method performs great effect in the retrieval of vertical air motions in the weak turbulence.When the turbulence is strong,the error cannot be ignored.The improved method presents good performance in the area with strong turbulence.