夏季南亚高压及西太平洋副热带高压强度变化与前期海温异常的关系

The influence of tropical ocean on the South Asia High and the Western Pacifica Subtropical High

本文利用1951—2010年NCEP/NCAR再分析月平均资料研究了热带海表面温度对南亚高压与西太平洋副热带高压发展变化的影响,得到以下主要结论:在两高压强年与暖海温年(两高压弱年与冷海温年)里,冬、春两季赤道印度洋、太平洋海温距平呈现显著的正?负?正(负?正?负)的厄尔尼诺(拉尼娜)现象,中南半岛附近的对流层高层产生异常西风(东风)气流,有利于(不利于)南侧异常反气旋环流的产生,从而促进(阻碍)南亚高压发展;菲律宾海域的对流层产生异常下沉(上升)气流,有利于(不利于)西北侧异常反气旋环流的产生,从而促进(阻碍)低层西太副高的发展。夏季,热带印度洋的暖海温(冷海温)有效地增加(降低)了当地的对流效应,使大气对流层温度增暖(减低),影响南亚高压与西太平洋副热带高压的发展。

The influence on both South Asia High(SAH)and the Western Pacifica Subtropical High(WPSH)during summertime is investigated in this paper with a development of a tropical sea surface temperature(SST),based on the NCEP/NCAR reanalysis data from 1951 to 2010.Some reasons for both development of those two systems have been researched:When the systems are both strong and the SST is warm(the systems are week and the SST is cold),in the winter and spring season the equatorial Indian?Pacific SST anomaly shows a significant positive-negative-positive(negative-positive-negative)pattern,which is like the El Nino(La Nina)phenomenon.A high-level westerly(easterly)wind flows near Indochina troposphere,which is helpful(against)for anomalous anticyclonic circulation in the south,so as to promote(block)the development of SAH.The sinking(rising)flow in Philippine area is conducive(unfavorable)to the anomalous anticyclonic circulation in the northwest side,so as to promote(block)the development of lower WPSH.In summertime,warming of the tropical Indian Ocean SST increase(decrease)the local convection effect effectively,making the tropospheric temperature rising(reducing),which affects SAH and WPSH.