2020年初夏贵州省降水异常特征及其历史相似性分析

Analysis of Features and Historical Similarities of the Precipitation Anomalies in Guizhou Province in Early Summer 2020

该文利用1961—2020年贵州省84个气象台站5月20日—7月10日的降水资料与NCEP/NCAR再分析资料,分析了贵州省初夏降水异常时空分布特征及其与海洋、大气环流的联系,以及对比2020年与历史相似年影响因子的异同。对比历史相似年,当初夏降水偏多时,大气环流纬向分布呈“两槽一脊”分布型,低压槽稳定维持在东亚中高纬附近。西太平洋副热带高压西伸脊点明显偏西,面积偏大,强度偏强。850 hPa水汽输送场上通过西北太平洋异常反气旋产生的异常西南风,向长江及其以南地区输送水汽,低层水汽输送偏强且辐合带位置相对稳定。前期春季热带印度洋偏暖和太平洋西暖东冷的异常海温加强了菲律宾反气旋,使西太副高稳定维持在西太平洋和东南亚地区,导致贵州省初夏降水偏多。

By using the NCEP\NCAR reanalysis data and rainfall data from the 84 stations in Guizhou province during 1961—2020,studied the relationship between the abnormal early summer rainfall and the sea surface temperature and atmosphere circulation,and also analyzed the similarities and differences of impact factors between the year 2020 and historical years when precipitation was positively anomalous.When there is more precipitation in early summer,zonal distribution of atmospheric circulation presented the“-+-”wave train.The trough remained stable near the middle and high latitude of East Asia.And the western ridge of the West Pacific subtropical high(WPSH)was obviously westward,the area of WPSH was bigger and the intensity of WPSH was stronger.On the 850 hPa vapor transport level,there was abnormal southwesterly wind caused by anticyclone in the Northwest Pacific transported water to the Yangtze River and its south,and the low-level water vapor transport was strong and the location of the convergence zone was stable.In the early spring,the warmer tropical Indian Ocean and the Pacific Ocean’s warm west and east cold abnormal sea temperature strengthened the anticyclone in the Philippines,which made the WPSH remain stable in the Western Pacific and Southeast Asia,as a result,Guizhou Province has more precipitation in early summer.