Intensified Western Pacific Convection Increases the Probability of Hot Extremes in the Middle East During the Boreal Spring.

Under global warming, the convective heating over the western Pacific (WP) has exhibited a significantly intensifying trend during the boreal spring, while the surface air temperatures in the Middle East (ME) have increased more rapidly than those in other tropical regions. Are these climate phenomena of the two regions physically connected? If yes, what are the responsible dynamical mechanisms involved? Utilizing the ERA5 reanalysis data and model simulations, this study reveals a significant seesaw variation in the convection and temperature trends between WP and ME. When convective heating intensifies over the WP, the ME tends to be drier and hotter during the spring, and vice versa. A further investigation indicates that the enhanced WP convective heating can induce anticyclonic circulation anomalies in the upper and middle troposphere over the Iranian and Tibetan plateaus. These anomalous high pressures extend westward, exhibiting a barotropic structure, which leads to stronger sinking motions, reduced cloud cover, and increased surface solar radiation over the ME. Consequently, these conditions result in drier and hotter soils and an increase in heatwave days in the ME. This study provides useful information for enhancing our understanding of the role of tropical WP climate change in influencing the upstream climate conditions with a focus on the ME. Plain Language Summary: Under global warming, the western Pacific (WP) has experienced a significant increase in convective heating during the spring, while the Middle East (ME) is seeing a faster rise in surface temperatures compared to other tropical regions. This study investigates whether these climate changes in WP and ME are interconnected and what mechanisms may be involved. The results show that when convective heating intensifies over the WP, the ME tends to become drier and hotter in the spring. The findings suggest that increased heating over the WP can lead to anomalous high pressures over the Iranian and Tibetan plateaus, which result in reduced precipitation, decreased cloud cover, and increased solar radiation, causing higher temperatures in the ME. This study enhances our understanding of how climate changes in the tropical WP can influence weather and climate conditions in the ME. Key Points: The convection in the western Pacific (WP) has been intensifying during spring in 1979–2022Surface air temperatures have been rising faster in the Middle East (ME) than in other tropical regionsThe intensified WP convection likely contributes to the increase in heatwave days over the ME [ABSTRACT FROM AUTHOR]