一次东北冷涡暴雨过程成因分析

Formation Mechanism of a Northeastern Vortex Rainstorm

利用常规气象观测资料、NCEP 1°×1°逐6h的再分析资料和FY-2E红外云图、TBB等资料,对2014年7月7—8日由东北冷涡引发内蒙古东北部的暴雨过程形成原因进行了天气学诊断分析,结果表明：1低空急流是主要水汽来源,不同地区出现暴雨的机制不同,兴安盟东部、呼伦贝尔市东南部由于槽前、切变南缘地面暖锋附近,中低空急流汇合处,强辐合抬升触发不稳定能量释放导致强天气的发生,而呼伦贝尔市西南部暴雨跟中上层冷涡的生成发展与对应的地面低压逐步耦合的动力作用相关;2湿位涡的分布对暴雨的发生、落区有较强的指示性作用,700hPa正负值区过度带的配置是暴雨发生发展的有利潜势,暴雨发生在700hPa等值线密集带和850hPa MPV2大于等于0的叠加区域内,700hPa正负过渡带附近,偏向于正值一侧;3最大降水量的雨强落后于云团TBB最低值1~2h,并不是强TBB与最强降水同步出现。

Using theconventional meteorological data,NCEP reanalysis data（horizontal resolution 1°×1°）,FY-2Esatellite images and TBB data,the heavy rain process happened on 7and 8July 2014 is studied in detail from the meteorological diagnostic analysis angle,which was caused by Northeast Cold Vortex and produced an effect on the northeast of Inner Mongolia.The main results are：（1）The main water vapor were carried by the Low level jet stream.Different regions had different formation mechanisms of heavy rainfall.The Eastern Xingan Meng and Hulun Beir are found to be located at front of trough and nearby the surface warm front in the south of the shear line,where were the high incidence area of severe weather caused by the instability energy release of strong convergence uplifting.However,the heavy rain happed at the southwest of Hulun Beir was closely associated with the germination and development of the cold vortex and the dynamic effect of the ground low pressure system.（2）The distribution of moist potential vorticity（MPV）is of very good instructive significance for heavy rain occurrence and precipitation area.The heavy rainfall occurred in the superimposed region of the area of anomalously dense isopleths of 700 hPa and the area of MPV2 ≥ 0at 850 hPa.（3）The maximum rainfall intensity appeared 1or 2hours behind the minimum TBB,and the maximum TBB and rainfall intensity did not occur in the same time.