Response of convectively coupled Kelvin waves under warming scenarios in a global storm-resolving model

This study investigates the response of convectively coupled Kelvin waves (CCKWs) under two warming scenarios using the ICOsahedral Non‐hydrostatic model (ICON) in its global storm-resolving configuration.  A control simulation (CTRL) is conducted using prescribed historical (1979–1997) sea surface temperatures (SSTs). Taking CTRL as reference, a simulation with a homogenously SST increase of 4 K (+4K) and another with a 4-fold increase in atmospheric CO₂ concentration (4×CO₂) are conducted.  Results show that CCKWs are substantially strengthened in the +4K experiment, exhibiting enhanced spectral power, faster phase speeds, and more active spatial activity, whereas nearly no change is found in the 4×CO₂ experiment. Under uniform SST warming, enhanced surface energy input-dominated by increased latent heat flux-supports stronger and deeper tropical convection, increasing the strength and coherence of convection-circulation coupling. We hypothesize that this enhanced coherence may shorten the adjustment timescale between convective heating and wave-related circulation, resulting in faster eastward propagation and enhanced wave variability. These results highlight the critical role of surface-driven flux enhancement in modulating convectively coupled tropical wave activity under warming.