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Advances in Meteorology
Volume 2014 (2014), Article ID 414015, 19 pages
Research Article

Meteorological and Back Trajectory Modeling for the Rocky Mountain Atmospheric Nitrogen and Sulfur Study II

1Air Resources Division, National Park Service, Fort Collins, CO 80523, USA
2Cooperative Institute for Research in the Atmosphere, Colorado State University, Fort Collins, CO 80523, USA
3AECOM, Inc., Fort Collins, CO 80525, USA
4Department of Atmospheric Science, Colorado State University, Fort Collins, CO 80523, USA

Received 17 January 2014; Accepted 28 March 2014; Published 8 May 2014

Academic Editor: Florinda Artuso

Copyright © 2014 Kristi A. Gebhart et al. This is an open access article distributed under the Creative Commons Attribution License, which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly cited.


The Rocky Mountain Atmospheric Nitrogen and Sulfur (RoMANS II) study with field operations during November 2008 through November 2009 was designed to evaluate the composition and sources of reactive nitrogen in Rocky Mountain National Park, Colorado, USA. As part of RoMANS II, a mesoscale meteorological model was utilized to provide input for back trajectory and chemical transport models. Evaluation of the model's ability to capture important transport patterns in this region of complex terrain is discussed. Previous source-receptor studies of nitrogen in this region are also reviewed. Finally, results of several back trajectory analyses for RoMANS II are presented. The trajectory mass balance (TrMB) model, a receptor-based linear regression technique, was used to estimate mean source attributions of airborne ammonia concentrations during RoMANS II. Though ammonia concentrations are usually higher when there is transport from the east, the TrMB model estimates that, on average, areas to the west contribute a larger mean fraction of the ammonia. Possible reasons for this are discussed and include the greater frequency of westerly versus easterly winds, the possibility that ammonia is transported long distances as ammonium nitrate, and the difficulty of correctly modeling the transport winds in this area.