WRF-CHEM modeling of tracers, photochemistry and organic aerosols: a focus on the CalNex and Uintah Basin field studies

Speaker: Ravan Ahmadov, NOAA ESRL CSD & CU CIRES

When: Wednesday, December 18, 2013, 3:30 p.m. Mountain Time
Location: Room 2A305, DSRC (NOAA Building), 325 Broadway, Boulder
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The state of the art fully coupled meteorology-chemistry model - Weather Research and Forecasting - Chemistry (WRF-CHEM) is a powerful modeling tool enabling researchers around the world to study air quality, atmospheric chemistry and meteorology-chemistry interactions from local to global scales. The WRF-CHEM model has been extensively applied to intensive field studies conducted by NOAA. In the first part of my presentation I will demonstrate results from the WRF-CHEM model with an updated secondary organic aerosol (SOA) scheme and evaluations focusing on aerosol composition during the CalNex 2010 field campaign. Evaluations of the model predicted meteorological and gas-phase species using the NOAA P3 aircraft and the CalTech surface observations will be presented as well. A number of sensitivity simulations were conducted in order to estimate the potential contribution of biogenic and different anthropogenic emission sources such as commercial cooking, diesel and gasoline vehicles to the OA burden over the Los Angeles basin. The role of the various SOA formation pathways - multigenerational volatile organic compound oxidation, semi- and intermediate volatile compounds in SOA modeling and the associated uncertainties will be discussed.

In the second part I will present some results from the WRF-CHEM modeling for the Uintah Basin Winter Ozone Studies in 2012 and 2013. For modeling purposes we have constructed a top-down emission inventory using the linear regression between the chemical species and methane (CH4) concentrations observed at a ground site. The simulations exhibit good agreement for CH4 and other chemical species compared to the observations. The model can reproduce elevated ozone (O3) events within the Uintah Basin. I will discuss major atmospheric transport and chemical processes contributing to high O3 mixing ratios over the basin. Also, model results using bottom-up emissions from the oil and gas wells based on the EPA NEI-2011 emission inventory will be presented.