Interannual and Interdecadal Variations of the Hadley Circulation and Its Connection with Tropical Sea Surface Temperature

Abstract

AbstractThe variations of the Northern Hemispheric Hadley circulation (NHHC) in winter and the Southern Hemispheric Hadley circulation (SHHC) in summer and their connections with tropical sea surface temperature (SST) on interannual and interdecadal scales are investigated by use of NCEP/NCAR wind data and NOAA SST data. The results indicate that the winter NHHC not only exhibits remarkably interannual and interdecadal variability, but also shows a positive trend. Accompanying the strengthened winter NHHC, its center shifts southward and its height ascends. The summer SHHC, lacking an obvious trend, exhibits decadal variations with a strong, weak and strong pattern. The results also show that a positive correlation between the NHHC and Nino3 region SST in winter exists, and this correlation changes on an interdecadal scale. It is also revealed that the Nino3 region SST is positively correlated with the NHHC in winter and negatively correlated with the SHHC in summer on an interannual scale, which means when the SST in the mid‐east Pacific becomes warmer (colder), both winter and summer Hadley circulations get stronger (weaker).