Evolution of Observed Cloud Organization within Tropical Rainfall Events during the DYNAMO/AMIE Field Campaign

Abstract

Tropical convective organization is important for the modulation of the climate on a range of spatial-temporal scales, however the physical processes controlling organization in the atmosphere are still not fully understood. The transient nature of observed convective organization presents challenges to being accurately replicated in models, and a limited number of available observations further challenge our understanding of their driving processes. Cloud organization indices allow us to capture the evolution of cloud organization processes, however results are often sensitive to the choice in existing index used. This project aims to use cloud organization metrics to better understand how convection organizes within rainfall events observed from S-PolKa radar during the DYNAMO/AMIE field campaign. Results show that convection is most organized after peak rainfall. However, the exact timing of greatest cloud organization depends highly on the choice of indices applied. This suggests organization does not lead to increased rainfall, but rather other factors are responsible for upscale growth of tropical convection. It is also found that convective organization of rainfall events depends on the intensity of rainfall, following a sequential process from development to peak rainfall and finally decay.