Jackson Tan - 613 Seminar Series

ORAU

In the tropics, half of the total rainfall comes from organized deep convection. A recent observational study has found that frequency of organized deep convection has increased over the past twenty-seven years. Here, we extend this work by investigating how this increase in organized deep convection, as well as changes in less organized forms of deep convection, contribute to the observed changes in tropical precipitation.

Cloud regimes derived from the International Satellite Cloud Climatology Project allow us to identify deep convection of different degrees of organization on the scale of a few hundred kilometers. By assessing the contributions of these regimes to precipitation, we find that the change in the frequency of organized deep convection can explain most of the observed spatial patterns of change in rainfall. In contrast, the contributions from changes in less organized forms of deep convection or changes in mean precipitation of organized deep convection is lower.

Our results identify organized deep convection as the link between changes in rainfall and in the dynamics of the tropical atmosphere, thus providing a framework for obtaining a better understanding of changes in rainfall. Given the lack of a distinction between the different degrees of organization of convection in climate models, our results highlight an area of priority for future climate model development to achieve accurate rainfall projections in a warming climate.