A41K-0228
The impact of ClNO2 production on tropospheric nitrogen oxides and oxidants in a global model
Thursday, 17 December 2015
Poster Hall (Moscone South)
Steven S Brown1, Alfonso Saiz-Lopez2, J F Lamarque3, Douglas E Kinnison3, Felipe Lopez-Hilfiker4, Joel A Thornton5, Lyatt Jaegle6, Dorothy L Fibiger7 and Erin E. McDuffie8, (1)NOAA Boulder, Boulder, CO, United States, (2)Spanish National Research Council, Zaragoza, Spain, (3)NCAR, Boulder, CO, United States, (4)University of Washington Seattle Campus, Seattle, WA, United States, (5)Univ Washington - Seattle, Seattle, WA, United States, (6)Univ Washington, Seattle, WA, United States, (7)National Science Foundation, Atmospheric and Geospace Sciences Postdoctoral Fellow, Arlington, VA, United States, (8)University of Colorado at Boulder, Boulder, CO, United States
Abstract:
Heterogeneous uptake of dinitrogen pentoxide, N2O5, to aerosol is one of the most important reactions controlling the global budget of nitrogen oxides, with subsequent impacts on oxidants such as ozone and hydroxyl radical. Nearly all global chemical models assume that this uptake proceeds through hydrolysis to produce nitric acid, effectively a terminal sink for nitrogen oxides. However, recent field studies have shown that the yield of nitryl chloride, ClNO2, from N2O5 uptake is significant in many locations. Because ClNO2 photolyzes subsequent to its nighttime production to recycle NO2 and produce atomic chlorine, a potent oxidant, the impact of heterogeneous N2O5 uptake and the role of ClNO2 on the scale and distribution of oxidants need to be re-assessed. Here we present simulations using CAM-Chem incorporating halogen chemistry (tropospheric and stratospheric, including geographic and time varying VSLs precursor emissions) along with different assumptions for the magnitude and spatial distribution of ClNO2 yields from N2O5. The model shows the largest effects of ClNO2 production on tropospheric ozone during northern hemisphere late winter and early spring. Simulations are compared to observations from recent field campaigns, including ClNO2 and N2O5 from the Wintertime INvestigation of Transport, Emissions and Reactivity (WINTER) study on the NSF / NCAR C-130 aircraft on the U.S. East Coast in February and March of 2015.
