“列车效应”诱发的一次河套地区致灾暴雨成因  

Causes of a Torrential Rainstorm Induced by “Train Effect” in Hetao Area

作　　者：张桂莲 杭月荷 付丽娟 张璐 包福祥[2] ZHANG Guilian;HANG Yuehe;FU Lijuan;ZHANG Lu;BAO Fuxiang(Inner Mongolia Autonomous Region Meteorological Observatory,Huhehot 010051,Inner Mongolia,China;Inner Mongolia Autonomous Region Climate Center,Huhehot 010051,Inner Mongolia,China)

机构地区：[1]内蒙古自治区气象台,内蒙古呼和浩特010051 [2]内蒙古自治区气候中心,内蒙古呼和浩特010051

出　　处：《高原气象》2020年第4期788-795,共8页Plateau Meteorology

基　　金：中国气象局预报员专项(CMAYBY2020-023);内蒙古自治区自然科学基金博士项目(2019BS04001);内蒙古气象局科技创新项目(nmqxkjcx201903);内蒙古气象局暴雨创新团队项目。

摘　　要：利用内蒙古自治区气象信息中心提供的全区785个自动气象站24 h和1 h降水量资料以及内蒙古河套地区鄂尔多斯(CINRAD/CB型)多普勒雷达资料,NECP的FNL(1°×1°)逐6 h再分析资料以及全球地形(1°×1°)资料,对2018年7月18-19日内蒙古河套地区致灾暴雨进行成因分析。结果表明,副热带高压成带状稳定少动,其西北侧500 hPa高空槽、中低层700~850 hPa"人"字型切变线和低空急流是暴雨发生的主要背景条件;暴雨期水汽条件表现为强西南支水汽输送和垂直辐合上升运动,水汽通量强度中心发展至700 hPa,水汽通量散度垂直辐合上升至500 hPa,有利于高效率强度大的短时强降水产生;"列车效应"即:由于阴山山脉的地形强迫作用导致的扰动不断输送至暴雨区且在雷达回波特征上表现为显著的东西向带状回波分布形势,是导致暴雨不断发展的重要动力过程,并且暴雨区表现出正涡度中心和负散度中心重合的准正压不稳定结构加剧了对流不稳定的发展。Using the 24 h and 1 h precipitation data of 785 automatic weather stations provided by the Inner Mongolia Autonomous Region Meteorological Information Center and the Ordos(CINRAD/CB)Doppler radar data from the Hetao area of Inner Mongolia,the FNL of NECP(1°×1°)6 h reanalysis data and global topographic(1°×1°)data,we analyzed the torrential rainstorm in Hetao area,Inner Mongolia from 18 to 19 July 2018. The results show that the stable and less moving subtropical high with its northwest trough at 500 hPa,the"herringbone"shaped shear line in middle and lower level,and low-level jet are the main background. The condition of water vapor during the rainstorm period presents strong southwest branch water vapor transport and vertical convergence ascending motion,and water vapor flux intensity center develops up to 700 hPa with vertical convergence of water vapor flux rising to 500 hPa. The"train effect"disturbances induced by the orographicforcing of the Yinshan mountain continuously and propagating over the rainstorm area,which are characterized by significant east-west axial band echoes in Radar reflectivity,is the key of the dynamic process for the persistent rainstorm. Furthermore,the quasi-positive pressure instability structure with the positive vorticity center and the negative divergence center coincide over the rainstorm area exacerbates the development of convective instability.

关 键 词：河套地区 致灾暴雨 带状回波 “列车效应” 地形强迫 

分 类 号：P458.121.1[天文地球—大气科学及气象学]