台风布拉万(1215)深入内陆所致的大暴雨成因分析

本文使用多种观测资料和NCEP再分析资料，对1215号台风布拉万北上深入内陆在黑龙江中部地区引发大暴雨过程进行追踪和诊断分析，探究此次大暴雨天气发生、发展的动力学、热力学和不稳定机制以及卫星云图特征。分析结果表明：大暴雨的发生是中低纬系统相互作用的结果，冷空气向东南方向移动增强了大气的斜压性，有利于斜压扰动的发展；对流层低层的对流不稳定和对流层中层的湿对称不稳定的共同存在，说明大气层结不稳定，为大暴雨的出现提供了有利的环境条件；对流层中低层形成了一个自下向上的正涡管，促使对流发展，散度场上表现为低层辐合、高层辐散的动力配置结构以及中尺度次级环流的出现均为暴雨的维持和加强提供了重要的动力机制；台风中心东侧的偏南和东南急流为大暴雨提供了充沛的水汽条件和热力条件。分析还表明地形对暴雨有增幅作用。

Analysis of Severe Rainstorm Caused by Typhoon Bolaven (1215) Invading Interior Territory

Based on various conventional observations and the NCEP reanalysis data, the associated thermodynamics, dynamic mechanisms, instability mechanism and the features of satellite images for the occurrence and evolution of severe rainstorm caused by typhoon Bolaven (1215) and cold air in central Heilongjiang are analyzed. The results suggested that the severe rainstorm results from the interaction of middle and low latitude circulation systems. The southeastward advance of cold air greatly enhances the baroclinicity, in favor of the development of baroclinic disturbances. During this rain storm process, the co existing of instability in the low troposphere and moist symmetry instability in the middle troposphere provides a powerful ambient condition for the occurrence of this rainstorm. The positive vortex tube in the mid low layer of the atmosphere drives the development of convection. Strong convergence at low levels and divergence at high levels, and mesoscale circulation provides dynamic conditions. The southerly and southeast jet in the east side of typhoon center provides abundant moisture and thermodynamic conditions. In addition, the terrain helps to increase the intensity of the rainstorm as well.