Simulating Deposition with a Regional Air Quality Model for the Rocky Mountain
Atmospheric Nitrogen and Sulfur Study (ROMANS)

Michael G. Barna
Air Resources Division, National Park Service, Fort Collins, CO

Marco A. Rodriguez
CIRA, Colorado State University, Fort Collins, CO

Kristi A. Gebhart, Bret A. Schichtel
Air Resources Division, National Park Service, Fort Collins, CO

William C. Malm
National Park Service, CIRA/CSU, Fort Collins, CO

Increased deposition to fragile ecosystems is anticipated as the population along Colorado’s Front Range continues to grow. In particular, there is concern with regard to nitrogen deposition at high elevation ecosystems. The Rocky Mountain Atmospheric Nitrogen and Sulfur Study (ROMANS) are currently underway, and are designed to investigate the pollutant sources that are contributing to nitrogen deposition at Rocky Mountain National Park (RMNP). A regional-scale air quality, CAMx (“Community Air Quality Model with Extensions”) is being used to simulate wet and dry deposition at RMNP during April and July, 2006. The model domain consists of a continental-scale 36 km domain, with nested 12 km and 4 km domains to address transport within the complex terrain of the Rocky Mountains. Wind fields and other meteorological inputs were provided by MM5 (Mesoscale Model, version 5), with available surface and sounder measurements incorporated into the observational data assimilation scheme. A detailed emission inventory, developed by the Western Regional Air Partnership for 2002, was updated for this study. In addition to the base emissions simulation, a series of conserved tracer simulations are being evaluated to bound the absolute contributions of numerous nitrogen sources within Colorado and beyond.