Precipitation Susceptibility of Monsoon Clouds to Aerosol Perturbations over India

Understanding the effect of aerosols on precipitation is the major scientific challenge in the current climate change research. Precipitation susceptibility relates a change in precipitation rate to a perturbation in cloud droplet number concentration and can be directly related to the power law forms. Precipitation susceptibility estimates were made for the first time for monsoon clouds over Indian region using High-Altitude surface and aircraft measurements of aerosol, cloud and precipitation during southwest monsoon seasons. A High-Altitude Cloud Physics Laboratory is established at Mahabaleshwar (17.9 N, 73.6 E, 1380 m above mean sea level), Western Ghats, India which is immersed in clouds most of the time during the monsoon season. Surface observations of rain intensity (R), cloud droplet number concentration (Nd), liquid water content (L) using an impact type disdrometer, cloud combination probe and a microwave radiometric profiler collected during Monsoon 2012 were analysed to understand the effect of aerosols on rain intensity and amount. Similarly, aircraft observations of cloud droplet number concentration and drizzle rate collected during Monsoon 2009 over a region in central India are analyzed. Data were grouped for different liquid water content bins and precipitation susceptibility is estimated as a slope of a linear fit between log R and log Nd. The patterns of precipitation susceptibility estimated from both the regions show similar variability with liquid water content regimes. Details on data, methodology and results will be presented.