低纬850百帕辐散风场的年变化及其在厄尔尼诺年的异常

ANNUAL VARIATION IN THE LOW-LATITUDE 850 hPa DIVERGENT WIND FIELD WITH ITS ANOMALY IN AN EL NIND YEAR

本文分析了约10年的850百帕月平均风场的辐散分量。结果表明:各季中月气候速度势场中存在3个辐合区和3个辐散区;季节变化明显的区域是南亚高原、南美洲和非洲;印度洋东部及低纬太平洋区域少变。辐散风场的年际异常与厄尔尼诺(反厄尔尼诺)事件关系密切,1982—1983年厄尔尼诺事件期间,辐散风场中有一个与之相应的异常过程存在。

Analysis is done of the divergence component of the monthlymean wind field at 850 hPa for a period of roughly 10 years. Resultsshow that three convergent and three divergent zones are observed inthe monthly climatic velocity potential fields for each of the fourseasons with marked seasonal change occurring over the South-AsianPlateau, South America and Africa and slight variation taking place inthe Eastern Indian Ocean and the low-latitude Pacific. The interannualanomalies of these divergent wind fields are found to bear a close relationwith E1 Nino/anti-E1 Nino events. During the 1982--1983 E1 Nino episode,for instance, the wind field shows an anomalous process associated with it.