冬、夏季印度洋越赤道经向翻转环流的年际变化

利用50 a的SODA资料对1月(冬季)和7月(夏季)印度洋越赤道经向翻转环流的年际变化进行研究。通过对2类典型年份的合成分析指出:1月份正异常年对应的经向翻转环流偏强,向北的经向热输送增加;7月份正异常年对应的经向翻转环流则偏弱,向南的经向热输送减少;1月份和7月份的负异常年皆与其正异常年相反;越赤道经向翻转环流有明显的年际变化,平均周期在4 a左右;经向翻转环流的年际变化和海面风场的变化密切相关。提出了反映1月和7月此环流年际变化的几个指数。

Interannual Variability of the Cross Equatorial Meridional Overturning Circulations in Winter and Summer for the Indian Ocean

The interannual variability of the cross equatorial meridional overturning circulation in January(winter) and July(summer) for the Indian Ocean is studied based on the SODA data covering 50 years.It is shown from decomposition analysis that the meridional overturning circulation in January is stronger in positive abnormal years,with larger northward meridional heat transports.In July,the meridional overturning circulation in positive abnormal years is weaker and the southward meridional heat transport is smaller.Opposite characteristics appear in negative-abnormal years,for both January and July.There is significant interannual variability with a period of about 4 years in the cross equatorial meridional overturning circulation.The interannual variability of such circulation is closely related to that of surface wind stress.Several indices that describe the anomaly of the cross equatorial circulation in January and July are proposed.