A synthesis of existing and new observations of air-snowpack exchanges to assess the arctic tropospheric ozone budget.

Emphasis Area: Atmospheric Chemistry

Principal Investigator: R. Honrath

Sponsor: NSF

Funding Level: $504,000

Period: 2007-2011

Abstract:

Photochemical processes occurring within snowpacks result in simultaneous destruction of ozone and release of NOx and radical precursor compounds, with the result that snowpack photochemistry can simultaneously destroy ozone (within the snowpack) and cause the production of ozone (in the lower atmosphere above the snowpack). In addition, biological processes in non-polar snowpacks result in the release of NO and can destroy ozone. This project aims to close existing gaps in understanding of snowpack processes affecting ozone, including ozone uptake to snow and the role of biological activity below snowpacks, NOx release from snow, and boundary-layer ozone production resulting from snowpack emissions of ozone precursors. A two-pronged approach including field measurements and chemistry-climate simulations will be used. Air/snow exchange fluxes of NOx and ozone will be determined at three separate locations which span the range of snowpack environments: polar glacial (at Summit, Greenland), arctic non-glacial (at Toolik Lake, Alaska) and midlatitude (in northern Michigan or Wisconsin). New parameterizations of snowpack processes will be developed and incorporated into single column model versions of the global chemistry-climate models ECHAM4 and ECHAM5-MESSy. The expected outcome of this effort is the first assessment of the impact of snowpack photochemical processes upon the arctic and subarctic tropospheric ozone budget, and a modeling framework suitable for assessing the expected impact that climate change will exert upon the tropospheric ozone budget through changing snowcover and permafrost extent.

Primary collaborations: Detlev Helmig, Univ. Colorado (eddy correlation ozone flux and ozone gradient measurements and other activities), Laurens Ganzeveld, Univ. Wageningen, Netherlands (chemistry-climate model development and simulations).