Analysis of the role of sea ice and frost flowers as a source of salt aerosol
Final Report Abstract
The joint project 'Sea ice Atmosphere Lagrangian Transport of SALT' aimed to investigate the processes linked to the generation of sea salt aerosol (SSA) from sea salt on ice - its generation, transport, and impact on atmospheric chemistry. Until end of 1980s it was believed that open ocean is the only source of SSA. Accordingly the SSA signature found in ice core data was interpreted by meridional transport from open ocean. However, recent findings have shown that the seasonality of SSA at the antarctic coastal stations can not be explained by long range transport from the open ocean source. Furthermore, the SSA samples collected at the coastal stations of Antarctica have shown sulfate depletion with respect to sodium. From this observation originated the hypothesis of a sea ice source of salt aerosols. One main aim of the SALT project was to understand the sea salt aerosol generation process in terms of sea ice characteristics and meteorological parameters. For this purpose a Lagrangian backward trajectory model based on sea ice remote sensing data and atmospheric reanalysis data was developed. The SSA concentration measured at Neumayer, Syowa and Dumont d'Urville was simulated considering the emission, dry deposition and transport of SSA in the atmospheric boundary layer. The size distribution was assumed as bimodal with one accumulation and one coarse mode. After a validation with the well-known source function for open water the model was used to test two different hypothesis for the aerosol generation. Neither the "blowing snow hypothesis" (Yang et aJ., 2008) nor the "frost flower hypothesis" (Kaleschke et al., 2004) could successfully explain the observed variability. However, large uncertainties about the wet deposition rate, the sea salt aerosol size distribution and the variability of the atmospheric boundary layer prevent definite conclusions.
Publications
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(2009), A three dimensional model study on the production of BrO and Arctic boundary layer ozone depletion, J. Geophys. Res.
Zhao, T. L., S.L. Gong, J. W. Bottenheim, J. C. McConnell, R. Sander, L. Kaleschke, A. Richter, A. Kerkweg, K. Toyota, and L. A. Barrie
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(2009), Comprehensive isotopic composition of atmospheric nitrate in the Atlantic Ocean boundary layer from 65S to 79N, J. Geophys. Res.
Morin, S., J. Savarino, M. Frey, F. Domine, H.-W. Jacobi, L. Kaleschke, and J. M. F. Martins
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(2010), Evidence of reactive iodine chemistry in the Arctic boundary layer, J. Geophys. Res.,115, D20303
Mahajan, A. S., M. Shaw, H. Oetjen, K. E. Hornsby, L. J. Carpenter, L. Kaleschke, X. Tian-Kunze, J. D. Lee, S. J. Moller, P. Edwards, R. Commane, T. Ingham, D. E. Heard, and J. M. C. Plane
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(2010), Satellite observations of long range transport of a large BrO plume in the Arctic, Atmos. Chem. Phys., 10, 6515-6526
Begoin, M., Richter, A., Weber, M., Kaleschke, L., Tian-Kunze, X., Stohl, A., Theys, N., and Burrows, J. P.
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(2011), Continuous 25-yr aerosol records at coastal Antarctica-I: inter-annual variability of ionic compounds and links to climate indices. Tellus B
Weller, R., D. Wagenbach, M. Legrand, C. Elsässer, X. Tian Kunze and G. König-Langlo
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Field and satellite observations of the formation and distribution of Arctic atmospheric bromine above a rejuvenated sea ice cover. Journal of Geophysical Research Atmospheres, 117, Issue D17, 2012
Son V. Nghiem, Ignatius G. Rigor, Andreas Richter, John P. Burrows, Paul B. Shepson, Jan Bottenheim, David G. Barber, Alexandra Steffen, Jeff Latonas, Feiyue Wang, Gary Stern, Pablo Clemente-Colón, Seelye Martin, Dorothy K. Hall, Lars Kaleschke, Philip Tackett, Gregory Neumann, Matthew G. Asplin
