一次暴雨过程受不同系统影响的动力热力场结构特征

Characteristic Analysis of Dynamic and Thermal Field Structure of a Rainstorm Affected by Different Affected Systems

本文使用常规观测资料、卫星云图、自动气象站降水量以及0.25°×0.25°的NCEP/NCAR再分析资料,对出现在东北地区北部受不同系统影响的连续2d暴雨过程的热力和动力场结构特征展开研究。结果表明:24日为暖锋锋生暴雨,暴雨范围大;25日为台风暴雨,暴雨出现在台风移动路径上,为狭长带状。暴雨是由MCS活动造成的,每次短时强降水均与TBB低值中心相对应,台风倒槽内的MCS强度比暖锋云系内的MCS弱,但是降水强度却更大。台风安比携带大量暖湿空气,其东侧的低空急流向北输送热量和水汽,水汽辐合集中在边界层内,台风暴雨的水汽辐合强度比暖锋暴雨更强烈,所造成的雨强更大。暖锋暴雨期间,小兴安岭迎风坡地形的辐合抬升作用明显;高层强辐散及地形辐合抬升作用对暴雨有较大贡献。台风暴雨期间,低空辐合,特别是水汽辐合作用对暴雨有较大贡献;辐合区位于台风倒槽附近,倒槽表现为冷锋性质。

Based on the conventional observational data,satellite images,automatic observational precipitation and NCEP/NCAR reanalysis data(0.25°× 0.25°),the characteristics of dynamic and thermal field structure of a rainstorm affected by different systems in the northern part of Northeast China on 24 and 25 July 2018 are analyzed.The major conclusions are as follow s:the rainstorm was caused by the warm front frontogenesis,and the rainstorm range was widespread on 24 Jul 2018.There appeared typhoon torrential rain on the typhoon movement path,manifested as a narrow rainfall belt on 25 Jul 2018.The rainstorm was caused by MCS(Mesoscale Convection System)activities,and each short-time heavy rainfall corresponded to a low value center of TBB.The intensity of MCS in the typhoon trough was weaker than that in the warm front cloud system,but the intensity of precipitation was greater.Typhoon Ampil carried a large amount of warm and wet air,and the low-level jet stream on its east side transferred heat and water vapor to the n o rth.The water vapor convergence was in the boundary layer,and the water vapor convergence intensity of the typhoon rainstorm was stronger than that of the warm front rainstorm,resulting in stronger rainfall.During the warm front rainstorm,the convergence and uplift of the windward slope of the Xiaoxingan Mountains were obvious.The high-level strong divergence and topographic convergence uplift contributed to the rainstorm.During the typhoon and rainstorm,the convergence at low altitudes,especially the convergence of water vapor in the lower layer,made a great contribution to the rainstorm.The convergence zone was located near the typhoon trough,and the typhoon trough had the properties of a cold front.