Weather Condition Analysis and Radar Echo Evaluation of Precipitation Enhancement Operation for a Stratiform Mixed Clouds

Zhou Yiling; Yao Zhanyu

doi:10.16765/j.cnki.1673-7148.2017.01.002

Abstract：The operational weather conditions and effect of the precipitation enhancement for a strati form mixed clouds in Taian,Shandong province is investigated by using the data of Doppler weather radar,routine weather and surface precipitation on May 8,2013.Whether weather conditions are conducive to the precipitation enhancement operation is judged and a method for estimating the effect and catalytic timing of seeding based on various parameters of radar echoes is discussed through analyzing the case by comparing the target cloud with the contrast cloud,as well as the changes in rainfall.The results are as follows.1) Good moisture conditions and dynamic conditions are provided for the precipitation operation owe to the favorable weather situations.2) Precipitation enhancement plays a certain positive effect in 12 min after seeding in the target cloud with all the values of radar echo parameters for the target cloud increase,while the enlargement rate of the contrast cloud is much smaller than that of the target cloud.And there are positive deviations between the target cloud and the contrast cloud such as echo top,echo volume,maximum reflectivity,vertically integrated liquid water content and precipitation flux are gradually increasing with their increase rates are respectively as follow:200.0％,288.2％,29.4％,above 65.0％ and 384.8％.3)A large increase appears in the affected area rainfall after seeding with the effect lasts 3 h,while its hourly rainfall is significantly higher than that of the contrast area.4)The optimum seeding time should be earlier than the original time of 12 min.5) Combined Doppler weather radar echo analysis with the general meteorological observations,the accuracy and scientificalness of precipitation enhancement effect evaluation can be improved.