Atmosphere-Snowpack Ozone Exchanges at Summit, Greenland and Their Role in the Polar Tropospheric Ozone Budget

Model sensitivity studies and prior field observations have shown that surface ozone fluxes over snow are an important process affecting tropospheric ozone levels in the Arctic. Yet measurements of ozone deposition velocities reported in the literature are highly variable, and the processes and chemical mechanisms impacting ozone behavior within and above the snowpack are not well understood. In order to address these deficiencies, a study with continuous, year-round measurements of ozone exchange between the atmosphere and the snowpack began at Summit, Greenland in June 2008. These observations include eddy-covariance ozone fluxes, ozone measurements in interstitial air at depths down to 3 meters below the snow surface, as well as intermittent measurements of near surface ozone profiles using an automated moving-inlet platform. Measurements of nitrogen oxides above and below the snow are also being made to investigate the connections between ozone and oxidized nitrogen species. A suite of near surface and boundary layer meteorological observations are employed in order to relate the chemical surface exchanges to boundary layer and synoptic transport of chemical species. This unique set of year-round measurements allows us to move toward an improved description of the seasonality and dependencies of surface ozone exchange over polar snow. The field observations are incorporated into the ECHAM chemical climate model. The goal of the modeling work is to assess how anticipated changes in snow chemical and physical properties from anthropogenic inputs and climate change will feedback on the ozone budget in the polar boundary layer, the free troposphere as well as ozone exchange between the Arctic and lower latitudes.