印度洋偶极子与中国秋季降水的关系

Relationship between the Indian Ocean Dipole and Autumn Rainfall in China

利用1950—1999年Hadley中心全球海温资料、NCEP/NCAR再分析资料以及国家气象局整编的160站降水资料,分析讨论了夏季印度洋偶极子与中国秋季降水的时滞关系及秋季印度洋偶极子与同期中国降水的关系。结果表明:夏、秋季印度洋偶极子均与中国南方秋季降水有很好的正相关关系;通过对印度洋偶极子时期秋季异常环流场特征分析,发现正偶极子时期中国西南部受中层槽前西南气流影响,带来充足水汽,同时低层为异常气旋性环流控制,使该地区降水增加。

On the basis of 1950--1999 fifty year data of Hadley Center global SST,NCEP/NCAR reanalysis and China 160 station precipitations, investigation has been conducted on the relationship between summer as well as autumn Indian Ocean Dipole （IOD） and autumn precipitation over China. Evidence shows that the IOD, both in summer and autumn,bears a close positive correlation with autumn rainfall over southern China. Further analysis shows that during the occurrence of positive IOD episode it is the southwestly（cyclonic） anomalies in the middle（lower） troposphere over southwest China that cause the plenty water vapour and then the increase of rainfall in that region.