Unprecedented East Asian Heat Dome in August 2022: Underrated Joint Roles of North Pacific and North Atlantic

Abstract

Caused by an unprecedented East Asian high-pressure, the Yangtze River Valley (YRV) in China suffered an extreme heat dome with record-breaking heatwaves and droughts in August 2022. Concurrently, extra-tropical oceans recorded unprecedented warm sea surface temperatures (SSTs). However, the combined influence of these warm SSTs on the YRV's extreme heatwaves remains unclear. By using observational data, simulations from the Community Earth System Model-Large Ensemble project, and numerical sensitivity experiments, we highlight the joint contributions of intensified air-sea interaction in the North Pacific and North Atlantic to the YRV's extreme heatwave. Further analysis indicates that the East Asian high-pressure exhibits a non-linear response to the intensity of SSTs in the North Pacific and North Atlantic, with a significant response only to the extreme warm SSTs. In addition, the uncertainty within the simulation of August high-pressure is explored, and the result indicates that the uncertainty could be physically rooted in the model's inability to initiatively simulate the coupled air-sea situation over the North Atlantic in July. To improve the simulation for the influence of mid-latitude SSTs, a coordinated coupled air-sea initial condition should be used to constrain the simulation. Moreover, such warm SSTs and the associated air-sea interaction can cause extreme high-pressures over Europe and western North America, offering an explanation for the compound extreme heatwaves over these two regions and China in 2022.