Exploring the Effects of Tropical Cyclone Suppression on Climate in Global Climate Models

Do tropical cyclones (TCs) play a significant role in global climate? TCs contribute to the meridional transport of energy, modulation of precipitation in the tropics and subtropics, and may impact the large-scale atmospheric circulation. Despite their relevance in climate, a unified theory of their formation and their impacts on climate remains elusive. To address this, we attempt to eliminate TC activity in global climate models (GCMs) to explore mechanisms required for cyclogenesis and evaluate the associated impacts on global climate. To eliminate TC activity, we suppress the wind-induced surface heat exchange (WISHE) feedback, which we assume to be critical to TC intensification, in GCM model runs. We then evaluate impacts of TC suppression on climate by comparing results with results from control experiments to identify differences in heat, momentum, and moisture. Preliminary results show that although suppressing WISHE reduces hurricane-strength TC frequency by over 90%, hurricane-strength TCs still form in GCMs, with properties similar to those in control runs. This indicates that suppression of additional mechanisms is required to fully eliminate TC activity, suggesting that WISHE is necessary but insufficient for TC intensification. With regards to impacts on climate, model output shows that TC suppression results in lower annually-averaged temperatures and specific humidities in the upper troposphere, with strongest reductions in the midlatitudes.