台风“烟花”衰减后引发江苏中部降水加强分析  

Analysis of Intensification of Precipitation in Central Jiangsu after Weakening of Typhoon"In-Fa"

作　　者：李静怡 武艳 席琳 薛丹 张庆池 LI Jingyi;WU Yani;XI Lin;XUE Dan;ZHANG Qingchi(Xuzhou Meteorological Bureau of Jiangsu Province,Jiangsu,Xuzhou 221000;Key Laboratory of Transportation Meteorology,CMA,Nanjing 210oo9)

机构地区：[1]江苏省徐州市气象局,徐州221000 [2]中国气象局交通气象重点开放实验室,南京210009

出　　处：《气象科技》2023年第6期835-847,共13页Meteorological Science and Technology

基　　金：徐州市气象局科研课题(202002);徐州市气象局科研课题(202105)共同资助。

摘　　要：2021年第6号台风“烟花”在7月28日衰减为热带低压后,台风外围螺旋雨带致使江苏中部接连出现降水突增现象。本研究利用常规观测资料、数值预报产品和ERA5再分析资料,对强降水过程进行分析。结果表明:ECMWF-FINE数值模式产品对于形势场预报较为准确,但中尺度CMA模式更能体现极端降水的量级和落区。分析降水增强原因可知,“烟花”移动时受到高空引导气流作用较小,其在安徽境内打转时,西风槽携带弱冷空气南下降低了大气稳定度并强迫暖湿空气抬升。高低空散度场与涡度场集中在较窄区域内,构成了垂直互耦的优势配置,有利于形成强烈且深厚的上升运动,是暴雨产生和持续的重要动力机制。强降水区位于湿位涡(MPV)负中心的暖湿气流中,MPV负值区可反映暴雨落区。MPV1和MPV2分布体现了冷空气入侵所引发的对流降水特征。此外,江苏中部位于螺旋云带右侧高湿高能区,东北气流与西南气流汇合形成了旺盛的线状对流云团,配合地面辐合线对中尺度系统的触发和维持,从而产生极端强降水。After the No.6 typhoon"In-Fa"in 2021 decayed to a tropical depression on July 28,the spiral rainbands around the typhoon caused a sudden increase in precipitation in central Jiangsu Province.Based on the conventional observation data,numerical forecast products and ERA5 reanalysis data,this paper analyzes the process of heavy rainfall.The results show that the ECMWF-FINE numerical forecast product was more accurate for forecasting the situation field.However,the mesoscale CMA models could reflect the magnitude and the extreme precipitation area.Analysis of the reasons for the intensification of precipitation shows that the movement of"In-Fa"was little affected by the guiding air from high altitude;the weak cold air carried by the westerly wind trough reduced the atmospheric stability and forced the warm and humid air to the east of the typhoon to lift when it moved around in Anhui Province.The high and low spatial divergence fields and vorticity fields were concentrated in a relatively narrow area,which constituted an advantageous configuration of vertical mutual coupling.It was conducive to the formation of strong and deep vertical motion,which was an important dynamic mechanism for the generation and persistence of heavy rainfall.The heavy precipitation area was in the warm and humid air flow area of the negative centre of the wet potential vortex(MPV).The negative area of MPV had indicative significance for the direction of the heavy precipitation zone.The distribution of MPV1 and MPV2 reflected the characteristics of convective precipitation caused by the invasion of cold air.In addition,the central part of Jiangsu was located in the high-humidity and high-energy region to the right of the spiral cloud belt.The northeast and southwest airflow converged to form strong linear convective cloud clusters,along with the mesoscale system,which triggered and maintained with the ground convergence line,resulting in extremelyheavyprecipitation.

关 键 词：台风“烟花” 极端强降水 对流不稳定 湿位涡 MPV 

分 类 号：P458[天文地球—大气科学及气象学]