Articles | Volume 7, issue 16
Atmos. Chem. Phys., 7, 4329–4373, 2007

Special issue: Air Ice Chemical Interactions (AICI)

Atmos. Chem. Phys., 7, 4329–4373, 2007
22 Aug 2007
22 Aug 2007

An overview of snow photochemistry: evidence, mechanisms and impacts

A. M. Grannas1, A. E. Jones2, J. Dibb3, M. Ammann4, C. Anastasio5, H. J. Beine6, M. Bergin7, J. Bottenheim8, C. S. Boxe9, G. Carver10, G. Chen11, J. H. Crawford11, F. Dominé12, M. M. Frey13,12, M. I. Guzmán14,9, D. E. Heard15, D. Helmig16, M. R. Hoffmann9, R. E. Honrath17, L. G. Huey18, M. Hutterli2, H. W. Jacobi19, P. Klán20, B. Lefer29, J. McConnell21, J. Plane15, R. Sander22, J. Savarino12, P. B. Shepson23, W. R. Simpson24, J. R. Sodeau25, R. von Glasow26,27, R. Weller19, E. W. Wolff2, and T. Zhu28 A. M. Grannas et al.
  • 1Department of Chemistry, Villanova University, Villanova, PA 19085, USA
  • 2British Antarctic Survey, Natural Environment Research Council, Cambridge, CB3 0ET, UK
  • 3Institute for the Study of Earth, Oceans and Space, University of New Hampshire, Durham, NH 03824, USA
  • 4Laboratory for Radio- and Environmental Chemistry, Paul Scherrer Institute, 5232 Villigen, Switzerland
  • 5Department of Land, Air {&} Water Resources, University of California at Davis, Davis, CA 95616, USA
  • 6Consiglio Nazionale delle Ricerche – Istituto Inquinamento Atmosferico (C.N.R. – I.I.A); Via Salaria Km 29,3; 00016 Monterotondo Scalo, Roma, Italy
  • 7School of Civil and Environmental Engineering and School of Earth and Atmospheric Sciences, Georgia Institute of Technology, Atlanta, GA 30332, USA
  • 8Air Quality Research Branch, Environment Canada, Downsview, Ontario, Canada
  • 9W. M. Keck Laboratories, California Institute of Technology, Pasadena, CA 91125, USA
  • 10Center for Atmospheric Sciences, Department of Chemistry, Cambridge University, Lensfield Road, Cambridge, UK
  • 11NASA Langley Research Center, Hampton, VA 23681, USA
  • 12Laboratoire de Glaciologie et Géophysique de l'Environnement,CNRS/Université Joseph Fourier-Grenoble, St Martin d'Hères Cedex, France
  • 13School of Engineering, University of California-Merced, Merced, CA 95343, USA
  • 14Currently at School of Engineering and Applied Sciences, Harvard University, Cambridge, Massachusetts, USA
  • 15School of Chemistry, University of Leeds, Leeds, LS2 9JT, UK
  • 16Institute of Arctic and Alpine Research, University of Colorado, Boulder, CO 80309, USA
  • 17Department of Civil and Environmental Engineering, Michigan Technological University, Houghton, MI 49931, USA
  • 18School of Earth and Atmospheric Sciences, Georgia Institute of Technology, Atlanta, GA 30033, USA
  • 19Alfred Wegener Institute for Polar and Marine Research, Bremerhaven, Germany
  • 20Masaryk University, Department of Chemistry, Brno, Czech Republic
  • 21Department of Earth and Space Science and Engineering, York University, Toronto, Ontario, Canada
  • 22Air Chemistry Department, Max-Planck Institute of Chemistry, P.O. Box 3060, 55020 Mainz, Germany
  • 23Dept. of Chemistry and Department of Earth and Atmospheric Sciences, Purdue Univ., West Lafayette, IN 47907, USA
  • 24Department of Chemistry and Geophysical Institute, University of Alaska Fairbanks, Fairbanks, AK 99775-6160, USA
  • 25Department of Chemistry, University College Cork, Cork, Ireland
  • 26Institute of Environmental Physics, University of Heidelberg, Heidelberg, Germany
  • 27School of Environmental Sciences, University of East Anglia, Norwich, UK
  • 28College of Environmental Sciences, Peking University, Beijing 100871, China
  • 29Department of Geosciences, University of Houston, TX 77204, USA

Abstract. It has been shown that sunlit snow and ice plays an important role in processing atmospheric species. Photochemical production of a variety of chemicals has recently been reported to occur in snow/ice and the release of these photochemically generated species may significantly impact the chemistry of the overlying atmosphere. Nitrogen oxide and oxidant precursor fluxes have been measured in a number of snow covered environments, where in some cases the emissions significantly impact the overlying boundary layer. For example, photochemical ozone production (such as that occurring in polluted mid-latitudes) of 3–4 ppbv/day has been observed at South Pole, due to high OH and NO levels present in a relatively shallow boundary layer. Field and laboratory experiments have determined that the origin of the observed NOx flux is the photochemistry of nitrate within the snowpack, however some details of the mechanism have not yet been elucidated. A variety of low molecular weight organic compounds have been shown to be emitted from sunlit snowpacks, the source of which has been proposed to be either direct or indirect photo-oxidation of natural organic materials present in the snow. Although myriad studies have observed active processing of species within irradiated snowpacks, the fundamental chemistry occurring remains poorly understood. Here we consider the nature of snow at a fundamental, physical level; photochemical processes within snow and the caveats needed for comparison to atmospheric photochemistry; our current understanding of nitrogen, oxidant, halogen and organic photochemistry within snow; the current limitations faced by the field and implications for the future.

Final-revised paper