天山北坡中部一次短时暴雨的卫星反演云参数特征及成因分析

Cloud parameter characteristics of aβ-mesoscale short-term rainstorm in the central of the northern slope of Tianshan Mountains

利用常规高空、地面观测、自动气象站、NCAR/NCEP FNL 0.5°×0.5°再分析资料和FY-4A卫星多通道扫描成像辐射计(AGRI)载荷L2级定量产品资料对2019年6月16日发生于天山北坡的石河子垦区短时暴雨天气过程的云参数特征及成因进行分析。结果表明:(1)此次短时暴雨过程发生在巴尔喀什湖附近的高空槽分裂的短波槽配合中低层700 hPa切变线和850 hPa辐合线共同影响的环流背景下。(2)黑体亮度温度(Temperature blackbody,TBB)的发展、合并与暴雨云团的快速发展、合并、加强有较好的对应关系,暴雨云团在暴雨区快速发展,成熟后稳定少动并与上游的云团不断合并加强。当暴雨云团TBB快速下降至-52℃以后开始出现降水,暴雨区主要发生在暴雨云团TBB等值线密集区,暴雨云团的云顶高度可发展至12 km,在云团发展过程中云顶相态由含有水云、冰云的混合云组成,但主要以过冷水云为主。(3)700 hPa切变线和850 hPa及地面辐合线的存在为暴雨提供了有利的动力条件,且地面辐合线稳定少动,有利于强有力的垂直上升运动携带充沛的水汽在暴雨区聚集致使暴雨发生,此次暴雨的水汽路径主要有偏西和偏南两条路径。

The cloud microphysical structure characteristics and the causes of a rainstorm weather process occurring on June 16,2019 in the Shihezi reclamation area,Xinjiang,China are analyzed using automatic weather station data,NCAR/NCEP FNL 0.5°×0.5°reanalysis data,and the L2 quantitative product data of FY-4A/AGRI.The results are as follows:(1)The rainstorm mainly occurred in the circulation background under the joint influence of shortwave trough at the bottom of Lake Balkhash trough and the 700-and 850-hPa shear and convergence lines,respectively.(2)Good correspondence was observed between the development and the consolidation of TBB and the rapid development and the consolidation of the rainstorm cloud cluster.After TBB dropped to−52℃,it began to rain in the rainstorm cloud cluster,and the rainstorm area mainly occurred in the dense area of the TBB isoline.The cloud top height of the rainstorm cloud cluster could develop up to 12 km.In the process of cloud cluster development,the cloud top phase was composed of mixed clouds that contain water and ice clouds;however,supercooled water clouds were mainly occupied.(3)The 700-and 850-hPa shear and convergence lines,respectively,and the ground provided favorable dynamic conditions for the rainstorm,the strong vertical ascending motion carried abundant water vapor,which leads to the occurrence of rainstorm,and the water vapor path of the rainstorm mainly had two paths-westward and southward.