Analysis of satellite measurements of halogen oxides in the Antarctic: source regions, transport and comparison to model simulations

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Sea ice is a major source of atmospheric sea salt in Antarctica. This recent finding triggered a change in paradigm for the paleoclimatic interpretation of polar ice core records. Moreover, the release of reactive gas-phase halogens from the salty ice surface and of salt aerosol is of major importance for the tropospheric chemistry. The presence of reactive bromine in the polar troposphere causes the often complete depletion of ozone in the boundary layer, and a fast oxidation of other trace species such as mercury and the biologically produced dimethyl sulfide (DMS). An oxidation product of the latter, methanesulfonic acid (MSA), and sea salt concentration from ice core records have been used as proxies to infer information about the past sea ice extent. We propose to investigate the processes related to the salt aerosol generation on the sea ice surface, the atmospheric salt transport, the halogen release, and the impact on the tropospheric composition in a joint project. Here we describe one part of this project: the remote sensing of tropospheric BrO and the analysis of source regions and transport patterns. The analysis of the sea ice parameters from remote sensing data, the development of a sea ice aerosol model and the investigation of the major ions from Neumayer station aerosol filter measurements as well as from existing ice core and snow pit records is part of a joint proposal by the University of Hamburg. The lagrangian modeling of aerosol transport and halogen chemistry is part of a parallel proposal from the MPI Mainz. The proposed joint project is embedded in the International Polar Year IPY core project "Air Ice Chemical Interactions (AICI-IPY)".