Linking Regional Changes in the Intensity Distribution of Daily Tropical Precipitation to Changes in Large-Scale Circulation

Abstract:

Global warming is expected to change the intensity distribution of daily tropical precipitation, with an increased frequency of heavy precipitation and reduced frequency of light precipitation. In general, this is likely to increase the risk of flooding, while also increasing the risk of long dry periods. However, on regional scales circulation change plays a major role in modulating this precipitation distribution change in climate model projections.

Changes in the globally-aggregated daily precipitation distribution have previously shown to be well-described by two idealised modes: an increase mode, whereby the amount of rainfall increases at all rain-rates; and a shift mode, where the distribution shifts towards heavier rain-rates. Here, we demonstrate that these idealised modes can be adapted so that they apply at regional scales. We propose a simple framework based on the dry static energy budget which provides a physical explanation of these idealised modes and relates regional daily precipitation distribution change to changes in large-scale circulation.