a1 Earth and Space Science Division, Jet Propulsion Laboratory, California Institute of Technology, Pasadena, CA 91109, USA
a2 Computation and Neural Systems, California Institute of Technology, 1200 East California Boulevard, Pasadena, CA 91125, USA
a3 Environmental Science and Engineering, California Institute of Technology, 1200 East California Boulevard, Pasadena, CA 91125, USA
a4 School of Chemistry, University of Bristol, Cantock's Close, Bristol BS8 ITS, UK
It is well established that the reaction of HO2 with NO plays a central role in atmospheric chemistry, by way of OH/HO2 recycling and reduction of ozone depletion by HOx cycles in the stratosphere and through ozone production in the troposphere. Utilizing a photochemical box model, we investigate the impact of the recently observed HNO3 production channel (HO2+NO → HNO3) on NOx (NO + NO2), HOx (OH + HO2), HNO3, and O3 concentrations in the boundary layer at the South Pole, Antarctica. Our simulations exemplify decreases in peak O3, NO, NO2, and OH and an increase in HNO3. Also, mean OH is in better agreement with observations, while worsening the agreement with O3, HO2, and HNO3 concentrations observed at the South Pole. The reduced concentrations of NOx are consistent with expected decreases in atmospheric NOx lifetime as a result of increased sequestration of NOx into HNO3. Although we show that the inclusion of the novel HNO3 production channel brings better agreement of OH with field measurements, the modelled ozone and HNO3 are worsened, and the changes in NOx lifetime imply that snowpack NOx emissions and snowpack nitrate recycling must be re-evaluated.
(Received April 06 2011)
(Accepted December 22 2011)
(Online publication March 06 2012)