ANALYSIS OF THE COLD AIR EFFECT ON AN EXTREME PRECIPITATION EVENT TRIGGERED BY AN INVERTED TROUGH OF TYPHOON HAIKUI(1211)  

作　　者：吴海英 陈海山 曾明剑 刘安宁 王伟丽 

机构地区：[1]School of Atmospheric Science, Nanjing University of Information Science & Technology, Nanjing 210044 China [2]Jiangsu Provincial Meteorological Observatory, Nanjing 210008 China [3]Jiangsu Institute of Meteorological Sciences, Nanjing 210009 China

出　　处：《Journal of Tropical Meteorology》2015年第3期211-221,共11页热带气象学报（英文版）

基　　金：Jiangsu Province Natural Science Fund(BK20131459);Science and Technology Department Social Development Project(BE2011818);National Meteorological Public Professional Science and Technology Program of China(GYHY201306010);National Sci-Tech Support Plan(2011BAK21B04)

摘　　要：Based on intensive automatic weather station data, satellite cloud imagery, NCEP reanalyzed data, and the simulation results from mesoscale numerical models, this study analyzes the characteristics and formation mechanisms of the mesoscale convection system(MCS) during the extreme precipitation event that was triggered by a weakened low-pressure inverted trough of Typhoon Haikui on August 10/2012. The results of this study show that cold air at the rear of a northeastern cold vortex creates thermodynamic conditions favorable to the development of extreme precipitation. The main body of the cold air is northward located so that the cold air invades only the middle layer of the periphery of the inverted trough. Thus, the cold air minimally affects the lower layer, which results in a vertically distributed structure of the temperature advection that augments the formation and development of convective instability stratification. In the middle troposphere, the cold air encounters the convergent, ascending, warm moist air from the low-pressure inverted trough, leading to frontogenesis. The frontogenesis enhances wind convergence which, in turn, further enhances the frontogenesis, and the positive feedback between these two forces augments the development of meso- and small-scale convection systems in the rainstorm region and its vicinity, which strengthens the upward transportation of water vapor from low layers and thickening of water vapor convergence and results in local heavy rains.Based on intensive automatic weather station data, satellite cloud imagery, NCEP reanalyzed data, and the simulation results from mesoscale numerical models, this study analyzes the characteristics and formation mechanisms of the mesoscale convection system （MCS） during the extreme precipitation event that was triggered by a weakened low-pressure inverted trough of Typhoon Haikui on August 10/2012. The results of this study show that cold air at the rear of a northeastern cold vortex creates thermodynamic conditions favorable to the development of extreme precipita- tion. The main body of the cold air is northward located so that the cold air invades only the middle layer of the periph- ery of the inverted trough. Thus, the cold air minimally affects the lower layer, which results in a vertically distributed structure of the temperature advection that augments the formation and development of convective instability stratifica- tion. In the middle troposphere, the cold air encounters the convergent, ascending, warm moist air from the low-pressure inverted trough, leading to ffontogenesis. The frontogenesis enhances wind convergence which, In turn, further enhances the ffontogenesis, and the positive feedback between these two forces augments the development of meso- and small-scale convection systems in the rainstorm region and its vicinity, which strengthens the upward transportation of water vapor from low layers and thickening of water vapor convergence and results in local heavy rains.

关 键 词：heavy rain cold air FRONTOGENESIS mesoscale convection system(MCS) 

分 类 号：P444[天文地球—大气科学及气象学]