DIAGNOSTIC ANALYSIS OF MEAN MERIDIONAL CIRCULATION ANOMALY IN LOW LATITUDES IN RELATION TO ZONAL MEAN SST ANOMALY

The mass stream function of zonal mean meridional circulation is calculated in terms of NCEP/NCAR monthly meridional wind speed and vertical velocity, and the climatic and anomalous features of zonal mean SST and meridional circulation are investigated. Results show that (1) a joint ascending branch of Northern and Southern Hadley circulation is on the side of the summer hemisphere near the equator ,being well consistent with the extremum of SST ,and a strong descending by the winter-hemispheric side.(2)El Nino-related SST in low latitudes is an important outer-forcing source for anomaly meridional circulation, which is affected by seasonal variation of basic airflow and SST , and interannual and interdecadal changes of SST .