The WRF_Chemistry Air Quality Model: Updates and Online/Offline Comparisons

This presentation will first describe the latest updates to the Weather Research and Forecasting (WRF) model as it is coupled to fully online chemistry. This model now includes many atmospheric chemistry routines covering biogenic emissions, deposition, photolysis, chemical mechanisms, and aerosols. Usually the chemistry and aerosol routines are solved in an “online” or “fully-coupled” fashion with the meteorological forecast model. In other words, the interactions and transport of meteorological, chemical, and aerosol species are calculated using the same physical parameterizations with no need to interpolate in time and/or space. However, the model can also be run using an offline method. This offline version still uses the same physics parameterization. Time averaged values of the meteorological fields are produced by the meteorological part of the model, and then interpolated in time to feed the chemical transport part of the model.

The presentation will cover the evaluation of the WRF/Chem model using a test bed dataset from the summer of 2004. In addition, we will show comparisons of the online simulation with offline simulations using different coupling intervals. The simulations were done with a 12-km horizontal resolution and coupling intervals of 60-, 30-, and 10-min. Averaged surface statistics as well as results from one case will be shown.