Impacts of Anthropogenic Pollution on Convective Clouds and Precipitation in Downwind Pristine Environment

Clouds and precipitation over the Amazon region could have very large susceptibility to aerosols: warm cloud base and humid conditions that might lead to strong thermodynamic invigoration by aerosols. Measurements obtained from GoAmazon2014 IOP field campaign suggest that anthropogenic pollution from the mega-city Manaus in Amazonia significantly impacts aerosol properties including number, composition and size distribution in the downwind areas of Manaus. The changes of aerosol properties would impact cloud properties, convection, and precipitation. In this study, we conduct simulations for such an observed case – March 17, 2014 using the improved chemistry version of the Weather Research Forecasting model (WRF-Chem) coupled with a spectral-bin cloud microphysics to explore how the Manaus plumes modify aerosol properties in the downwind areas and how the changes of aerosol properties impact convection, clouds and precipitation in the influenced area. We evaluate our model simulations with observations from radar and aircraft measurements in addition to the precipitation data from rain gauges and TRMM.  We investigate in detail how aerosols change convective dynamics, thermodynamics, and microphysics and what is the significance of the impact of anthropogenic pollution.