夏季北大西洋三极型海温异常与中国西南地区气温年际变化的联系

利用1951—2016年Hadley中心海温资料、NCEP/NCAR再分析资料和全国160站气温资料，研究了夏季北大西洋三极型海温异常与中国气温年际变化的联系及可能机制。结果表明，夏季北大西洋三极型海温异常与同期中国西南地区气温年际变化存在显著的负相关关系。夏季北大西洋“-+-”三极型海温异常激发的北半球中高纬欧亚遥相关波列，引起贝加尔湖地区位势高度升高，产生反气旋性环流异常，并引起东亚地区位势高度降低，产生气旋性环流异常。西南地区在对流层中下层位于贝加尔湖异常反气旋性环流的东部和东亚异常气旋性环流的西部，在两者的共同作用下，受异常偏北气流影响，有利于冷空气南下和堆积。与此同时，对流层高层的东亚副热带西风急流位置偏南，西南地区位于急流南侧的异常上升气流中。此种环流形势配置导致中国西南地区气温降低，反之亦然。

Relationship between North Atlantic SSTA tripole and interannual temperature variation in Southwest China in summer

Based on the sea surface temperature (SST) data of Hadley Center, NCEP/NCAR reanalysis data and the temperature data of 160 stations in China from 1951 to 2016, the association and possible mechanism between the North Atlantic SST anomaly (SSTA) tripole and interannual temperature variation in China in summer are investigated.Results show that there is a significant negative correlation between the North Atlantic SSTA tripole and the interannual temperature variation in Southwest China in summer.The Eurasian teleconnection wave train in the middle and high latitudes of the Northern Hemisphere excited by the North Atlantic SSTA "-+-" tripole in summer causes the geopotential height of Lake Baikal to rise, resulting in an anticyclonic circulation anomaly, and causes the geopotential height of East Asia to decrease, resulting in a cyclonic circulation anomaly.Southwest China is located in the east of the anomalous anticyclonic circulation in Lake Baikal and the west of the anomalous cyclonic circulation in East Asia in the middle and lower troposphere.Under the combined action of the two, affected by the anomalous northerly flow, it is conducive to the southward movement and accumulation of cold air.At the same time, the East Asian subtropical westerly jet in the upper troposphere is located in the south, and Southwest China is located in the anomalous updraft on the south side of the jet stream.This circulation configuration leads to the decrease of temperature in Southwest China, and vice versa.