Analysis of sea surface temperature (SST) data robustly detects dipole-pattern decadal anomalies in the southern Atlantic and Indian Oceans (SAIOs) which co-occur like twins, termed as the Atlantic-Indian Twin Dipoles (AITDs). The mechanisms governing the AITDs are investigated by analyzing observational datasets and climate model simulations and performing ocean model experiments. We show that the AITDs are coupled with alterations in subtropical highs that involve a variety of regional air-sea processes. Specifically, wind-driven coastal ocean dynamics and cloud-controlled radiative heating play key roles in the South Atlantic, while oceanic upwelling and perturbed turbulent heat flux by air temperature advection is more important in the Indian Ocean. Interdecadal Pacific Oscillation and Southern Annular Mode are conducive to the AITDs by modulating the subtropical highs. Our results highlight the trans-basin linkage between the SAIOs, providing implications for predicting the Southern-Hemisphere climate and regional extremes.

sea surface temperature,decadal,internal,southern indian ocean,south atlantic,AITD