Chesapeake Bay Airshed Model (Bay Airshed Model)

Objective The Chesapeake Bay Airshed Model (Bay Airshed Model) provides estimates of nitrogen deposition resulting from changes in emission from utility, mobile, and industrial sources because of management actions or growth

Developer The Bay Airshed Model was developed by USEPA and the Chesapeake Bay Program Office by combining the Grimm and Lynch 2000; 2005 wet deposition regression model and a continental-scale air quality model of North America called the Community Multi-scale Air Quality Model (CMAQ).

Contact information Lewis Linker,, 410-267-5741, Chesapeake Bay Program Office, 410 Severn Ave., Suite 112, Annapolis, MD 21403.

Inputs Data from atmospheric deposition monitoring stations are used to inform the Bay Airshed Model of wet deposition during precipitation events (snow or rain) and of dry deposition through hourly emission estimates and meteorological data on a continental scale for continuous daily input.

Outputs The Bay Airshed Model is used to provide inputs of nitrogen from wet and dry atmospheric deposition to the Chesapeake Bay Watershed and Water Quality Models. The Bay Airshed Model is linked to the Bay Watershed Model through atmospheric deposition to land surfaces and free flowing streams and rivers, and to the Bay Water Quality model through direct atmospheric deposition to the tidal surface waters of the Chesapeake Bay.

User The Bay Airshed Model is used by USEPA and the Chesapeake Bay Program Office for the development and implementation of the Chesapeake Bay TMDL.

Scales of Relevance The CMAQ model uses a grid scale system on a continental/national level of approximately 36 km by 36 km. The Bay Airshed Model further refines this grid scale to a 12 km by 12 km grid for the Chesapeake Bay watershed.

Other The Bay Airshed Model incorporates CMAQ scenarios for management actions required by the Clean Air Act (CAA) for future emission reductions from national control programs on stationary and mobile sources.

Sponsors/funders USEPA and the Chesapeake Bay Program Office