Isolating the Thermodynamic Response of Tropical Convection to Column Moisture

In the tropics, the relationship between column relative humidity and precipitation is straight forward. With increasing moisture present in the column, the rate of precipitation increases exponentially above a given threshold. However, precipitation does not depend solely on moisture availability, atmospheric dynamics also plays a significant role. This analysis describes mechanisms for studying the influence that moisture has on tropical precipitation without the underlying influence large-scale circulation has on mean precipitation rates.

Utilizing the RAMS model, we simulated deep convective environments with constant surface convergence initialized with over seven-hundred different tropical soundings launched in the Maldives during the DYNAMO field campaign. In previous observational studies, mean precipitation from ground observations increased exponentially with increasing column relative humidity. However, in these simulations, the mean precipitation rate grew linearly with increasing column relative humidity. The origin and effects of this discrepancy will be discussed further, along with its implications for the investigation of moist tropical dynamics.