92nd American Meteorological Society Annual Meeting (January 22-26, 2012)

Tuesday, 24 January 2012: 8:30 AM
Transport and Deposition of Reactive Nitrogen Species in Rocky Mountain National Park
Room 342 (New Orleans Convention Center )
Jeffrey L. Collett Jr., Colorado State University, Fort Collins, CO; and K. B. Benedict, C. M. Carrico, S. Raja, F. M. Schwandner, M. Schurman, D. Day, E. Levin, A. P. Sullivan, T. Lee, A. J. Prenni, S. M. Kreidenweis, W. C. Malm, and B. A. Schichtel

Increases in reactive nitrogen deposition are a growing concern in the western United States. The Rocky Mountain Airborne Nitrogen and Sulfur (RoMANS) study was conducted to improve our understanding of the sources and transport of airborne nitrogen and sulfur species within Rocky Mountain National Park (RMNP) as well as their deposition pathways. Two initial field campaigns were conducted, in spring and summer 2006, to characterize pollutant transport and deposition during seasons with historically high nitrogen inputs. A year-long field campaign in 2008-09 provided a more comprehensive look at seasonal wet and dry deposition budgets and transport patterns. Measurements at the RoMANS core study site included wet deposition fluxes (nitrate, ammonium, organic nitrogen) as well as concentrations of key particle (ammonium, nitrate) and trace gas (ammonia, nitric acid, NOx, and NOy) species. Reactive nitrogen species concentrations and deposition fluxes in the park are typically low in winter, reflecting relative isolation of this high elevation region from major emission sources. Deposition increases in spring and summer, reflecting increased precipitation and more direct transport from important source regions, including urban and agricultural regions. Wet deposition of ammonium and nitrate are the most important contributors to nitrogen deposition, followed by wet deposition of organic nitrogen and dry deposition of gaseous ammonia. Dry deposition of gaseous nitric acid and other NOy species are somewhat less important, while dry deposition of particulate nitrate and ammonium make only minor contributions to the total reactive nitrogen deposition budget. Because the park is located west (typically upwind) of the nearest large urban and agricultural source regions, even short periods of transport from the east (associated, for example, with low pressure passage), sometimes accompanied by heavy precipitation, make a disproportionate contribution to RMNP reactive nitrogen deposition budgets.

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