Reducing Tropical Cyclone Activity in Global Climate Models by Evaporative Suppression

Abstract What would a world without tropical cyclones look like? Although such a world is unrealistic, addressing this question would reveal the role tropical cyclones (TCs) play in modulating the climate system. In this study, we begin to address this question by introducing a novel algorithm for reducing TC activity in TC‐permitting global climate models (GCMs) through suppression of wind‐induced surface heat exchange (WISHE) at grid points where TC‐like conditions are detected. This algorithm, abbreviated as “SWISHE,” was implemented in a suite of GCM simulations developed by NOAA's Geophysical Fluid Dynamics Laboratory and compared to a control suite of simulations with no perturbations. Application of SWISHE resulted in a model‐mean 44% reduction of TC frequency compared to control simulations, with TCs of hurricane‐strength reduced by approximately 90%. Aggregate analysis of TCs reveals that TCs in the SWISHE simulations are weaker, as peak 10‐m horizontal wind speeds decrease by a model‐mean of 3.9 m s −1 and minimum sea‐level pressures increase by a model‐mean of 4.7 hPa. Composite analysis is used to confirm that SWISHE effectively suppressed latent heat fluxes in grid cells with TC‐like conditions. The results presented herein are intended to provide a first step in establishing methodology to understand upscale impacts of TCs on the climate system.