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arXiv · 2607.23001

Transition to double-cell mock Walker circulations with surface warming explained by periodic convection

Heng Quan·Yi Zhang·Guy Dagan·Stephan Fueglistaler
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Abstract

Idealized mock Walker simulations are widely used to study the interactions between overturning circulation and convection in the tropics. Previous studies documented a transition from a single-cell to a double-cell mock Walker circulation when the average sea surface temperature exceeds 300 K. Here, we ascribe the transition to the emergence of periodic convection with warming due to stronger convectively-coupled waves. In cold simulations, the warm pool is dominated by steady deep convection, which results in a single overturning cell. In hot simulations, the warm pool is alternately dominated by deep convection and a stratiform mode, resulting in lower and upper cells respectively. This study suggests that the Walker circulation in a warmer climate may feature complex structural changes in addition to a weakening in strength, and highlights the profound impacts of convection on overturning circulation.

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Heng Quan, Yi Zhang, Guy Dagan, Stephan Fueglistaler. 2026-07-25. Transition to double-cell mock Walker circulations with surface warming explained by periodic convection. https://arxiv.org/abs/2607.23001

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