南京周边地区夏季对流云降水的雷达回波特征与人工增雨

THE CHARACTERISTIC OF RADAR ECHO OF CONVECTIVE CLOUD PRECIPITATION AND ITS APPLICATIONS IN THE OPERATION OF ARTIFICIAL PRECIPITATION STIMULATION AROUND NANJING IN SUMMER

本文利用1998～2002年南京713数字化天气雷达资料,对南京周边地区(距南京150km范围内)7、8、9三个月所有有高显的对流云降水回波进行了统计分析。统计结果发现南京及其周边地区夏季对流云降水回波在平显上以带状为主,所占比例超过为58.2%,其次是孤立的对流云降水回波,所占比例达到22.6%。在高显上,回波顶高在0℃层以下的降水回波较少,不到10%,回波顶高在0℃～-10℃之间的占11.7%,在-10℃～-20℃之间的占15.3%,-20℃以上的达到63%以上,说明南京及其周边地区夏季对流云中暖云的降水几率很小,大部分为发展旺盛、负温区比较深厚的对流云,这种云是人工增雨作业最理想的云。本文的研究为正确把握作业的时机、催化的部位及用弹量,以便有效地作业,提供了依据。

Using the 713-type digital weather radar data of Nanjing from 1998 to 2002,the echo of convective cloud precipitation that showed higher in July,August and September around Nanjing(in the distance of 150 km) was analysed.We found that in this area,about 58.2 percent of the echo was zonary,and about 22.6 percent of echo was isolated in the plane vision.But in the height vision, the precipitation echo was almost 10 percent in the layer where the temperature of echo peak was under the 0 ℃ layer, 11.7 percent in the layer where the temperature of echo peak was between 0 ℃ and -10 ℃, 15.3 percent in the layer where the temperature of echo peak was between -10 ℃ and -20 ℃, and upwards of 63 percent in the layer where the temperature of echo peak exceeded -20 ℃. We can draw a conclusion that the precipitation probability of warm cloud in the convective cloud was very small, and the convective cloud with big negative temperature was favourable condition of artificial precipitation stimulation.This paper could give some evidence when and where to perform the operation.