Sensitivity of Tropical Extreme Precipitation to Surface Warming in Aquaplanet Experiments Using a Global Nonhydrostatic Model

Increases of atmospheric water vapor holding capacity with temperature (7% K-1-8% K-1, CC-rate) can lead to increasing extreme precipitation (EP). Observations show that tropical EP has increased during the last five decades with a rate higher than in the extratropics. Global climate models (GCM's) diverge in the magnitude of increase in the tropics, and cloud-resolving models (CRM's) indicate correlations between changes in tropical EP and organization of deep convection. We conducted global-scale aquaplanet experiments at a wide range of resolutions with explicit and parameterized convection to bridge the gap between GCM's and CRM's. We found increases of tropical EP beyond the CC rate, with similar magnitudes when using explicit convection and parametrized convection at the resolution it is tuned for. Those super-CC rates are produced due to strengthening updrafts where extreme precipitation occurs, and they do not exhibit relations with changes in convective organization. Plain Language Summary Theory and observations indicate tropical extreme precipitation might increase with global warming. Projections from climate models agree on increases in the extratropics, but not in the tropics. More idealized simulations indicate links between increases of tropical extreme precipitation and changes in the spatial organization of the meteorological systems producing those extremes. Using a novel model approach, we found that tropical extreme precipitation increases with warming more than expected due to increases in the dynamics of the extreme precipitation systems, whereas changes in the spatial organization have a small role. Key Points The sensitivity of tropical extreme precipitation to warming is larger than the Clausius-Clapeyron rate Results are more sensitive to horizontal resolution, when convection is parametrized than explicitly resolved Super Clausius-Clapeyron rates are mainly due to dynamical changes, but appear unrelated to changes in indicators of convective organization