P52 Multiscale application of the WRF-CMAQ coupled modeling system for the Mid-Atlantic 2011 DISCOVER-AQ campaign

Gilliam, Robert, Wyat Appel, Jonathan Pleim, and Rohit Mathur, United States Environmental Protection Agency

Over the last decade US EPA air quality modeling has transitioned from short term episodes over small regions of the US, to full annual CONUS simulations at 36 km and more recently 12 km grid scales. In many applications, however, finer scale simulations are necessary and as computer capabilities continue to increase it will become more standard to run on these finer grids rather than the coarser scales of the past. Thus, we demonstrate our current capability of retrospective modeling, both meteorology and air quality, in a complex urban-coastal environment at 12, 4 and 1 km grid scales using the coupled WRF-CMAQ system. The Mid-Atlantic US centered over Baltimore, MD was chosen because of the observation rich DISCOVER-AQ projected headed by NASA during the summer of 2011. We examine model performance at these various grid scales and for a number of options including data assimilation techniques, physics and initialization in an effort both improve our own modeling and to guide others working on similar problems.