超低空急流形成的爬、绕流对长白山地区一次突发性暴雨的影响  

Impact of flow over and flow around caused by super low-level jet on a sudden rainstorm over the Changbai Mountains

作　　者：刘成瀚 王月 阎琦 谭政华[1,2] 刘硕 焦浩然 金妍 LIU Chenghan;WANG Yue;YAN Qi;TAN Zhenghua;LIU Shuo;JIAO Haoran;JIN Yan(Institute of Atmospheric Environment,China Meteorological Administration,Shenyang 110166;Liaoning Meteorological Observatory,Shenyang 110166;Shenyang Meteorological Bureau,Shenyang 110000;Shanghai Meteorological Center,Shanghai 200030)

机构地区：[1]中国气象局沈阳大气环境研究所,沈阳110166 [2]辽宁省气象台,沈阳110166 [3]沈阳市气象局,沈阳110000 [4]上海中心气象台,上海200030

出　　处：《暴雨灾害》2023年第3期273-282,共10页Torrential Rain and Disasters

基　　金：国家重点研发计划项目(2018YFC1507305);辽宁省气象局科研项目((202302,ZD202224,LNCP202301);中国气象局预报员专项(CMAYBY 2019-024);中国气象局东北冷涡重点开放实验室重点项目(2021SYIAEKFZD02、2021SYIAEKFZD03);环渤海区域科技协同创新基金项目(QYXM2021104)。

摘　　要：为了研究、揭示超低空急流与地形作用对暴雨的增幅机制,以2021年7月14日夜间发生在辽宁东部长白山地区的一次山地突发性暴雨为例,利用辽宁省地面观测降水数据和ERA5再分析数据,针对超低空急流形成的爬流及绕流对此次暴雨的影响进行研究,结果表明:(1)在东北冷涡东南部、副热带高压后部的有利环流背景下,偏南低空、超低空急流建立,为辽宁东部带来充沛的水汽和能量,降水的阶段性变化与低空急流的强度、位置、方向存在一定关系。(2)山地与平原过渡区的地形高度差强迫气流产生爬流运动,爬流所强迫的垂直运动由下至上逐渐减弱,大值区位于山地坡面上,山地区域爬流极值中心处于雨带中心位置,地形的爬流运动对降水范围及强度至关重要。(3)以东西方向为主导的绕流对暴雨区域局地涡旋的形成具有一定贡献,并且绕流对暖湿气流在降水中心起到汇聚的作用,间接为空气抬升提供增幅效果。爬流、绕流共同作用下,坡地区域次级环流上升支触发对流发展,不稳定能量释放,导致山区局地大暴雨的出现。The purpose of the paper is to study the mechanism of the interaction between super low-level jet and terrain to enhance rain-storm.Using the surface observation precipitation data of Liaoning Province and ERA5 reanalysis data,this paper analyzes a sudden moun-tain rainstorm that occurred in the Changbai Mountains,eastern Liaoning Province on the night of 14 July 2021,focusing on the role of flow around and flow over in this rain-storm.The results show that:(1)under the favorable circulation background of the southeast of the North-east Cold Vortex and the rear of the Subtropical High,the southward low-level jet and super low-level jet are established,which brings abun-dant water vapor and energy to the eastern part of Liaoning.The periodic change of precipitation is related to the intensity,location and direc-tion of low-level jet.(2)The terrain height difference in the transition area of the mountain plain forces the airflow to generate the flow over.The vertical ascent forced by the flow over gradually weakens from bottom to top.The maximum value area is located on the mountain slope.The extremum center of regional flow over is located in the center of the rain belt,and the flow over caused by terrain is specially important to the range and intensity of the precipitation.(3)The east-west direction-dominated flow around has a certain contribution to the formation of the local vortex in the rainstorm area,and the surrounding flow plays a role in converging the warm moist current in the precipitation cen-ter,and indirectly provides an amplifica-tion effect for the air upraise.Under the combined action of flow over and flow around,the upswing branch of secondary circulation in the sloping area triggers convective development and releases unstable energy,which leads to the occur-rence of local heavy rainstorms in mountainous areas.

关 键 词：暴雨 超低空急流 爬流 绕流 地形 

分 类 号：P445[天文地球—大气科学及气象学]