Modulation of the Central Pacific El Niño on the Relationship Between the Hadley Circulation and Tropical SST

Abstract Based on observational data, the effects of Central Pacific (CP) El Niño events on the relationship between the Hadley circulation (HC) and tropical sea surface temperature (SST) under different meridional structures are investigated. The variability of HC and SST have been decomposed into equatorially symmetric and asymmetric components to detect their relationship. The explained variances of the equatorially asymmetric and symmetric components of the HC's principal modes both decreased in the CP El Niño events. Compared to climatology, the responses of HC to SST under different meridional structures are suppressed during CP El Niño events. It has been discovered that SST variations in the tropical eastern Pacific (EP) are responsible for the different response of HC to tropical SST. The EP SST anomalies exhibit inhomogeneous variations during CP El Niño events, with a greater amplitude in the north EP, resulting in enhanced variation of the equatorially asymmetric SST. The modulation of the CP El Niño on the relationship between the HC and tropical SST provides evidence for its complex climate effects.