SR型与EAP型遥相关“结合模态”对2020年江淮入梅初期强降水的影响  

Impact of the“Combined Modality”of Silk-Road and East Asia-Pacific Teleconnection Patterns on the Heavy Precipitation in the Early Stage of Meiyu in the Yangtze-Huaihe River Region in 2020

作　　者：郭紫薇 王黎娟[1] GUO Ziwei;WANG Lijuan(Key Laboratory of Meteorological Disaster,Ministry of Education(KLME)/Collaborative Innovation Center on Forecast and Evaluation of Meteorological Disasters(CIC-FEMD)/Joint International Research Laboratory of Climate and Environment Change(ILCEC),Nanjing University of Information Science&Technology,Nanjing 210044)

机构地区：[1]南京信息工程大学气象灾害教育部重点实验室/气象灾害预报预警与评估协同创新中心/气候与环境变化国际联合实验室,南京210044

出　　处：《大气科学》2023年第4期1171-1182,共12页Chinese Journal of Atmospheric Sciences

基　　金：国家自然科学基金项目41975085、41975087。

摘　　要：利用ERA5逐日再分析资料和中国气象局提供的逐日站点降水资料,分析了丝绸之路型(Silk-Road,SR)与东亚—太平洋型(East Asia–Pacific,EAP)遥相关的“结合模态”对2020年江淮梅雨入梅的影响,结果表明“结合模态”可以触发江淮流域的持续性降水。2020年6月初,负SR型(Silk-Road)和正EAP型(East Asia–Pacific)同时出现,并且位相差达到6月份最大值,二者协同作用下导致2020年入梅时间异常偏早。主要表现为:(1)负SR型引起西风急流加速,促使急流入口区南侧的江淮流域上空出现强的高层辐散。(2)负SR型有利于南亚高压东移,正EAP型有利于西太平洋副热带高压西移,二者相向而行。负SR型和正EAP型于6月9日位相差达最大,此时南亚高压和西太平洋副热带高压重叠于120°E左右,有利于江淮流域持续性降水。(3)低层东亚中、低纬度有一对与正EAP型相关的异常“气旋—反气旋”环流,使低空(20°~35°N,100°~125°E)盛行强西南气流,中纬度的偏北气流有利于干冷空气向南输送,与西南暖湿气流汇合于江淮流域上空,带来强烈的水汽辐合,也使得大气的局地上升运动更为强烈。Using the daily reanalysis data of ERA5(The fifth generation European Centre for Medium-Range Weather Forecasts atmospheric reanalysis of the global climate)and the daily station data of precipitation provided by the China Meteorological Administration,the influence of the“combined modality”of the Silk-Road(SR)pattern and East Asia–Pacific pattern(EAP)teleconnection on the heavy precipitation in the early stage of Meiyu in the Yangtze–Huaihe River region in 2020 is analyzed.The results showed that the“combined modality”could trigger continuous precipitation in the Yangtze–Huaihe River region.At the beginning of June 2020,the negative phases of the SR pattern and the positive phases of the EAP appeared simultaneously,and the phase difference maximized in June.The synergy of the two resulted in abnormal precipitation in the early stage of Meiyu in 2020.The main results are as follows.(1)The negative phases of the SR pattern accelerate the westerly jet stream,promoting strong divergence at 200 hPa over the Yangtze–Huaihe River region in the south of the jet stream’s entrance area.(2)The negative phases of the SR pattern are conducive to the eastward movement of the South Asia high,whereas the positive phases of the EAP are conducive to the westward movement of the western Pacific subtropical high,and the two move toward each other.The negative phases of the SR pattern and the positive phases of the EAP showed the largest difference on June 9,2020.At this time,the South Asia high and western Pacific subtropical high overlapped at approximately 120°E,which is conducive to continuous precipitation in the Yangtze–Huaihe River region.(3)There are anomalous“cyclone–anticyclone”circulations at 850 hPa related to the positive phases of the EAP in the middle and low latitudes over East Asia,which makes the prevailing strong southwest airflow in the low altitudes(20°–35°N,100°–125°E).The northerly airflow at middle latitudes is conducive to the transportation of dry and cold air to the south

关 键 词：江淮梅雨 SR型与EAP型“结合模态” 西太平洋副热带高压 南亚高压 水汽通量 

分 类 号：P466[天文地球—大气科学及气象学]