Roles of Shallow, Deep, and Organized Convection in the Indian Summer Monsoon Overturning
This study investigates the roles of different types of convection in the Indian summer monsoon (ISM) overturning using a convection-permitting regional model. A cloud classification and tracking technique is used here to decompose the 2009 ISM simulation into the clear sky, shallow convection, precipitating congestus, isolated deep convection, and mesoscale convective system (MCS) regimes. The statistical properties of simulated convective systems are compared with satellite observations. Results show the convection-permitting seasonal simulation realistically captured the spatiotemporal and rainfall characteristics of convective systems during the ISM. An isentropic analysis technique is then adopted here to examine the contributions of different convective systems to the total monsoon overturning. Analyses indicate that MCSs and isolated deep convection have similar contributions to the total vertical mass, water, and energy transports during the ISM. However, the per event vertical transports associated with MCSs is around 40 times stronger than that associate with isolated deep convection. The vertical mass and energy transports associated with MCSs and isolated deep convection peaking in the upper troposphere, which is mostly contributed by the updraft over stratiform region and also partially contributed by the deep convective updraft. Below the melting level, Congestus shows larger contributions to the total vertical mass, water, and energy transport than MCSs and isolated deep convection. The vertical transports produced by shallow convection are confined below 2 km. The subseasonal variability of the vertical mass, water, and energy transports associated with different convective systems are also studied here. The vertical transports associated with MCSs and isolated deep convection show stronger subseasonal variability than that associated with congestus and shallow convection.