Thermodynamical and cloud microphysical response during the transition from southwest to northeast monsoon

Abstract

The thermodynamical and microphysical response during the transition from southwest to northeast monsoon season is studied. Unique mixed phase cloud observations from the Cloud Aerosol Interaction and Precipitation Enhancement Experiment (CAIPEEX) and ground based observations from Integrated Ground Observation Campaign (IGOC), high resolution (3km) mesoscale forecasts with the nested Weather Research and Forecasting (WRF) model are used in the study. Convective available potential energy (CAPE), liquid water path (LWP) and precipitable water (PW) increased 3days before the onset and further enhanced with the onset of the northeast monsoon. A systematic decrease in lifting condensation level (LCL) height and increase in midlevel moisture before and during the onset period are observed, which resulted in increase in moist static energy in the midlayer for supporting deeper convection during the onset. Cloud microphysical response is noted with the mixed phase cloud observations of liquid water and ice water content. The model has simulated the mixed phase clouds in the area of detailed observations. Major cloud microphysical changes observed are (a) shallow warm clouds before the onset, (b) elevated supercooled liquid water content at the tops of clouds and (c) low ice water content during the onset period compared to subsequent periods after the onset with more ice water content.