P18 Implementation and initial application of a new chemistry-aerosol option in WRF/Chem (CB05-MADE/VBS SOA) for simulation of aerosol indirect effects

Wang, Kai, Khairunnisa Yahya, and Yang Zhang, North Carolina State University

WRF/Chem v3.4.1 offers a number of chemistry and aerosol options in simulating regional air quality and its feedbacks into meteorology. Three options include an advanced secondary organic aerosol (SOA) module based on the Volatility Basis Set (VBS) approach: RACM-MADE/VBS, MOZART-MOSAIC/VBS, and SAPRC99-MOSAIC/VBS. None of these options enable the simulation of aerosol indirect effects. In this work, a new chemistry-aerosol option is developed in WRF/Chem v3.4.1 to enhance its capability in simulating aerosol indirect effects with the advanced VBS SOA. The 2005 Carbon Bond mechanism (CB05) that is widely used for regional/urban atmospheric chemistry modeling has been incorporated into WRF/Chem and coupled with the existing aerosol module MADE and the VBS SOA module (referred to as CB05-MADE/VBS) in WRF/Chem. This new chemistry-aerosol option has been linked with existing model treatments for various feedback processes to simulate chemistry-aerosol-radiation-cloud feedbacks such as aerosol semi-direct effects on photolysis rates of major gases, aerosol indirect effects on cloud droplet numbers, and cloud effects on shortwave radiation. This new option is also being linked with the cloud chemistry module in the convective cloud parameterization. WRF/Chem with the CB05-MADE/VBS is being applied to the continental U.S. for the July 2006 episode as part of the Air Quality Model Evaluation International Initiative (AQMEII) phase II model intercomparison that focuses on online-coupled models. The anthropogenic emissions are based on the 2008 National Emission Inventory. The meteorology-dependent emissions such as biogenic emissions, sea-salt emissions, and dust emissions are based on online modules. The predictions of meteorology, chemical concentrations, and dry and wet deposition fluxes are being evaluated with available surface and satellite data. The impacts of updated model treatments on meteorology and air quality as well as their interplay will be investigated through sensitivity simulations.