摘要
利用FY2C卫星观测反演得到的云物理特征参数,结合雷达、微波辐射计和地面雨量等资料,综合分析了2008年7月17日中国安徽一次强降水过程的云合并特征。结果表明:对流云团发展合并是这次强降水发生的主要原因,同一区域内FY2C卫星反演的云光学厚度、雷达回波以及地面降水的分布演变具有较好的一致性,强降水落区与云光学厚度大值区以及雷达强回波区基本对应;对流云团中的液水分布不均匀,以团块状结构为主,对流云团合并时,常先有云体上部(云顶)的合并,一旦云中不均匀的液水合并,合并部位的云光学厚度迅速增加,地面微波辐射计观测的整层液水含量跃增,地面将会出现强降水;一般降水增强之前云顶抬升,光学厚度增大;若云顶高但光学厚度较小时,地面降水一般不明显,光学厚度与降水的关系更密切;对流云团合并初期,云底由小粒子组成,T-re图上表现为深厚的凝结增长区域,合并时整层云粒子的有效半径增长明显,粒子相态达到混合相态区和冻结层的温度不断升高。
Based on Chinese satellite in geosynchronous orbit（FY2C）information on cloud physical characteristics parameters of the retrieval,and observations by radar,microwave radiometer and precipitation on ground,the structural features of cloud merging of a strong precipitation process are analyzed in Anhui Province,China on 17 July 2008.Results show that the development of convective clouds merging is the main reason for the occurring of heavy precipitation.The cloud optical thickness retrieved by FY2C satellite is found to be well consistent with radar echo of the corresponding region and the evolution of surface precipitation distribution.The heavy rainfall areas are in good agreement with the those of big cloud optical thickness and strong radar echo.Cloud liquid water distribution is very uneven and mainly in group block structure.The top of clouds often merge in the initial stage of convective cloud merging.Once the uneven liquid water in clouds unites,the cloud optical thickness in the combined parts increases rapidly,the whole layer of liquid water content from the ground microwave radiometer changes dramatically,and the ground heavy precipitation occurs.The statistic result shows that the top of cloud rises,and its optical thickness often increases before the reinforcing of precipitation.If the top of cloud is high with small optical thickness value,precipitation on ground is usually not obvious.The optical thickness of cloud is more related to precipitation.In the initial period of convective clouds merging,the clouds base consists of small particles,showing a deep zone of diffusional growth on the map of T-re relations.Then,the effective radius of cloud droplet of total layer significantly increases,and the mixed phase and glaciation temperature is warmer.
出处
《大气科学学报》
CSCD
北大核心
2011年第2期170-179,共10页
Transactions of Atmospheric Sciences
基金
中国气象局气象关键技术集成与应用项目(CMAGJ2011M71)
国家"十一五"科技支撑课题(2006BAC12B07)
关键词
对流云团合并
对流云结构
降水特征
convective clouds merging
convective cloud structure
precipitation characteristics
