2019年盛夏最大降水环流成因分析

Causative Analysis of the Maximum Precipitation Circulation During the Peak Summer of 2019

利用1961-2020年黑龙江省盛夏(7-8月)降水量、NCAR/NCEP大气再分析和Nino34 SST资料,分析2019年盛夏黑龙江降水异常与ENSO事件背景下大尺度环流特征。结果表明:2019年盛夏黑龙江省降水处于多水时段,ENSO暖事件多发期降水偏多发生的概率增加。指出了2019年降水特点主要受东北冷涡与3次台风北上相互作用,发生6次重大降水过程;500 hPa高度距平场为西北-东南向呈“+、-、+”形势;西太平洋副热带高压明显偏东,脊区向北伸展有利台风北上;低纬主要有3支强南风距平气流北上进入气旋环流,为维持台风暴雨提供充足水汽;黑龙江中部和东部地区最大上升气流速度出现在600-300 hPa高度,也是台风活跃区,辐合明显,黑龙江省强降水出现在东部最大降水中心,落区位于三江平原北部鹤岗至萝北。

Utilizing precipitation data from Heilongjiang Province during the peak summer months(July-August)of 1961-2020,atmospheric reanalysis from NCAR/NCEP,and Nino 3.4 SST data,this study analyzes the characteristics of large-scale circulation associated with the precipitation anomalies in Heilongjiang during the summer of 2019 under the backdrop of ENSO events.The findings indicate that the summer of 2019 in Heilongjiang experienced a period of higher precipitation,with an increased likelihood of excessive rainfall during the frequent warm phases of ENSO.The precipitation characteristics of 2019 were predominantly influenced by the interaction of the Northeast Cold Vortex with three northward-moving typhoons,resulting in six major precipitation events.The 500 hPa geopotential height anomaly presented a northwest-southeast orientation in a“+,-,+”pattern;the Western Pacific Subtropical High was notably shifted eastward,extending northward which facilitated the northward movement of typhoons.At lower latitudes,three strong southward anomaly airflows moved north into the cyclonic circulation,providing ample moisture for the typhoon-induced heavy rainfalls.The strongest upward air currents in Heilongjiang's central and eastern regions occurred between 600-300 hPa,coinciding with the active typhoon zone.This convergence was marked,with intense precipitation occurring in the eastern precipitation center of Heilongjiang,particularly over the northern part of the Sanjiang Plain from Hegang to Luobei.