Interannual impact of tropical southern Atlantic SST on surface air temperature over East Asia during boreal spring

Abstract

Using reanalysis data and simulations, this study revealed a pronounced negative interannual relationship between tropical southern Atlantic (TSA) sea surface temperature (SST) and East Asian surface air temperature (SAT) during boreal spring (March–May). Results confirm that the March–May TSA–SST anomaly can be considered an independent tropical driver unrelated to El Niño–Southern Oscillation. A possible mechanism linking TSA–SST and East Asian spring SAT involves an atmospheric wave train, energy conversion, and potential vorticity (PV)–θ dynamics. The anomalous TSA–SST induces an anomalous Walker circulation, which initiates a wave train that extracts energy from a westerly jet and propagates toward East Asia. Subject to PV–θ dynamics, the East Asian PV anomaly embedded within this wave train leads to bowed isentropes and resultant notable anomalous East Asian SAT. In particular, the bootstrapping results suggest that TSA–SST anomaly can cause an approximately sevenfold increase in the occurrence probability of extreme East Asian spring SAT.