Indirect radiative forcing of climate due to aerosols over the continental United States simulated by the two-way coupled WRF-CMAQ model

In this study, we first implemented indirect aerosol radiative forcing in the two-way coupled WRF3.3-CMAQ5.0 modeling system by including parameterizations for both cloud droplet and ice number concentrations calculated from the CMAQ-predicted aerosol particles The resulting cloud droplet and ice number concentrations are provided to the Morrison cloud microphysics scheme, which includes a two-moment treatment of cloud water (mass and number) and cloud ice (mass and number), to estimate aerosol effects on cloud and ice optical depth and microphysical process rates for indirect aerosol radiative forcing (including first, second and glaciations indirect aerosol forcing). The cloud drop effective radius and cloud ice effective radius from the output of the Morrison cloud microphysics scheme are used in the RRTMG and CAM radiation schemes affecting the radiation fields. Evaluations of model performance on shortwave cloud forcing (SWCF), longwave cloud forcing (LWCF), cloud optical depth, cloud fraction, cloud effective radius, and PM2.5 are carried out over the continental U.S during the summer of 2006 by comparing to satellite observation data such as CERES and MODIS and field experimental data such as 2006 TexAQS/GoMACCS.