Sensitivity of Tropical Extreme Precipitation to Surface Warming in
Aquaplanet Experiments Using a Global Nonhydrostatic Model
Abstract
Increases of atmospheric water vapor holding capacity with temperature
(7-8%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.