资源环境科技发展态势分析平台

The meridional structure of sea surface temperature (SST) plays an important role in determining the variations of the Hadley circulation (HC). The quantitative differences in the HC caused by the changing meridional structures of SST over seasonal cycles remain unclear. To determine the quantitative response of the HC to the meridional structure of SST during the seasonal cycle, this study decomposes the variations of the SST and HC into two components: equatorially asymmetric components (i.e., SEA for SST and HEA for HC) and equatorially symmetric components (i.e., SES for SST and HES for HC). Variations in HEA (HES) are closely associated with those in SEA (SES). In this study, five atmospheric reanalyses and two SST reanalyses are analyzed, focusing on the period of 1979-2013. The response amplitude of HEA to SEA is about four times than that of HES to SES in most of the reanalyses. This result provides a possible explanation for the dominance of the equatorially asymmetric mode over the variability of the HC during the seasonal march.