Convective Available Potential Energy and Precipitation in a Cloud-Resolving Model Simulation of Indian Summer Monsoon

Abstract

Relationship between convective available potential energy (CAPE) and precipitation is explored in a season-long cloud-resolving model (CRM) simulation of Indian summer monsoon. The location of maximum precipitation and CAPE does not always coincide in a CRM simulation. The diurnal land surface heating is shown to have an effect on CAPE and precipitation over ocean. Convective inhibition energy is shown to have a significant effect on the location of precipitation. It is shown that mass flux parameterizations which depend on CAPE consumption do not get the location or magnitude of precipitation right at CRM resolution. It is emphasized that once the model resolution starts approaching cloud scale, the basic assumption of convective quasi-equilibrium is not sufficient and representation of organized mesoscale convective systems becomes imperative. Present-day cumulus parameterizations do not include any representation of organized mesoscale convective systems. We show that CAPE consumed by these systems not only triggers vertical motion but also contributes to horizontal motion of the system.