基于Cloudsat的降水云和非降水云垂直特征

Comparing Vertical Structure of Precipitation Cloud and Non-precipitation Cloud Using Cloudsat

  • 摘要: 降水云是人工增雨作业的主要对象,了解降水云系的垂直结构对于人工增雨可播条件的选择至关重要。利用Cloudsat卫星2008年3月—2009年2月资料,首先通过大量个例分析并结合地面降水量观测验证Cloudsat卫星识别降水云方法的合理性,在此基础上,统计分析了华北和江淮地区降水云与非降水云的垂直结构特征。统计结果表明:降水云与非降水云垂直结构存在明显差异, 两地区降水云云底高度都在2 km以下,非降水云的云底高度以高于2 km为主。两地区单层降水云云厚以大于6 km为主,多层降水云云厚以2~4 km为主,非降水云云厚以小于2 km为主。两地区降水云夹层厚度集中于1~2 km,非降水云夹层厚度集中在4 km以上。江淮地区多层云降水频率略高于华北地区。

     

    Abstract: Precipitation cloud is the main target of artificial rain enhancement operation. Understanding the vertical structure of precipitation cloud is essential to choose seeding conditions. Based on the data of Cloudsat, the vertical structure of precipitation cloud and non-precipitation cloud in North China and Jianghuai Area from March 2008 to February 2009 are analyzed.First of all, the approach of judging precipitation cloud with Cloudsat is validated effectively by lots of examples. Then precipitation cloud and non-precipitation cloud are analyzed by a statistical analysis to get the vertical structure characteristics. Results show that precipitation cloud and non-precipitation cloud vertical structures are different. The cloud base height of single-layer and multi-layer precipitation cloud is less than 2 km. The cloud base height of non-precipitation single-layer cloud is mainly above 2 km in both two areas, the annual mean frequencies are 55% in North China and 51% in Jianghuai Area. Cloud thickness of single-layer precipitation cloud is mainly lager than 6 km in these two areas, and the annual mean frequencies are 67% in North China and 73% in Jianghuai Area.Cloud thickness of precipitation multi-layer cloud is mainly between 2 km and 4 km, and the frequency is 36% in the two areas. Cloud thickness of non-precipitation cloud is mainly below 2 km. The frequency is all more than 50% for single or multi-layer cloud. The precipitation cloud thickness of multilayer cloud except interlayer is mainly between 1 km and 2 km, the annual mean frequencies are 33% in North China and 34% in Jianghuai Area. The non-precipitation cloud thickness of multilayer cloud except interlayer is mainly above 4 km, the annual mean frequencies are 41% in North China and 44% in Jianghuai Area. The annual mean height of cloud top and cloud base in precipitation cloud are different from non-precipitation cloud, the annual mean height of cloud top and cloud base in precipitation cloud are 8.7 km and 0.7 km in North China, 9.85 km and 0.7 km in Jianghuai Area. On the other hand, the annual mean height of cloud top and cloud base in non-precipitation cloud are 7.45 km and 2.8 km in North China, 7.8 km and 2.75 km in Jianghuai Area, respectively.

     

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