Unraveling the Indian Monsoon's Role in Fueling the Unprecedented 2022 Marine Heatwave in the Western North Pacific

Abstract

An unprecedented marine heatwave (MHW) event occurred in the middle-high latitude of the western North Pacific in the summer of 2022. We demonstrate that enhanced precipitation thousands of kilometers away fueled this extreme MHW event in July 2022. In the upper atmosphere of the MHW region, a persistent atmospheric blocking system is formed, which reduces convection and cloud cover and increases shortwave radiation at the ocean surface, leading to higher sea surface temperatures. Atmospheric perturbations induced by latent heat release from the extreme precipitation in the Indian summer monsoon region enhance this atmospheric blocking through the propagation of quasi-stationary Rossby waves. Our hypothesis is verified by using a numerical model that is forced with the observed atmospheric anomalous diabatic heating. This study sheds light on how a subtropical extreme event can fuel another middle-high latitude extreme event through an atmospheric bridge.