利用FY-3A卫星云图对一次暴雨过程的特征云参数分析

利用FY-3A卫星MERSI资料，结合高空常规观测、地面雨量资料，对2009年6月28日湖北梅雨期暴雨过程的卫星云图和特征云参数进行综合分析。结果表明：楔状云（V型云）是强对流产生的标志，楔尖是云顶最冷、云顶温度梯度最陡之处；短时强降水通常发生在上升运动剧烈的位置，即在高分辨率的可见光图像上可清晰识别出上冲云顶、纹理及暗影等强对流云特有结构的区域；利用模糊C均值聚类方法得到的自动化云分类结果显示，此次强对流云主体被划分为“积雨云”类，其平均隶属度系数达0．81；地面小时雨量与云顶黑体亮温呈负相关，而与云光学厚度、云粒子有效半径呈正相关。

Analysis on characteristic cloud parameters of a heavy rain event based on satellite cloud images from FY-3A

Using the FY-3A/MERSI data combined with the upper-air and surface observations an analysis is made on the satellite cloud images and characteristic parameters of a rainstorm cloud occurred on June 28, 2009 in Hubei province. The results show that V-shaped cloud （wedge-shaped cloud） is a sign of strong convection originated, and the wedge tip region usually is accompanied by the lowest cloud top temperature and the biggest TBB gradient. Short-term severe precipitation often occurs in the position where strong updraft motion exists, namely, the unique structures of convective cloud such as the overshooting cloud top, texture and shadow can be clearly identified in the high-resolution visible image. Major pixels of the strong convective cloud are classified as ＂cumulonimbus＂ cluster group by fuzzy C-mean clustering method, and membership coefficient reaches 0.81. One-hour rainfall intensity has a good positive correlation with the cloud optical thickness / effective particle radius and has a negative correlation with the blackbody brightness temperature.