Sea Salt Aerosol above Arctic Sea Ice – sources, processes and climate impacts (SSAASI-CLIM)

Aerosol models for example do currently not capture aerosol maxima in the Arctic winter/spring observed at high latitudes. Recent field campaigns provide first evidence of a hypothesized source of SSA from salty blowing snow (BSn) above sea ice. During storms salty snow gets lofted into the air and undergoes sublimation to generate SSA. Additional but minor SSA sea ice sources are frost flowers and open leads. The impact on radiation and clouds of SSA from this new source of SSA above sea ice is not known. However, a quantitative understanding of natural aerosol processes and climate interactions is needed to provide a baseline against which to assess anthropogenic pollution reaching the Arctic and evaluate the success of mitigation measures. We therefore propose to determine the SSA source, fate and potential impact on Arctic climate associated with blowing snow above sea ice and other sea ice sources. To do this we seek funding to participate in the year-long Multidisciplinary drifting Observatory for the Study of Arctic Climate (MOSAiC) to observe aerosol processes in the central Arctic ocean throughout all seasons. Proposed measurements on the sea ice and on-board "FS Polarstern" include particle size and concentration (sub-micron to snow particle size), INP concentrations, and a range of chemical properties using aerosol filters. Sampling of snow on sea ice, brine, frost flowers will constrain the local source of SSA. Tethered balloon launches will yield information on the fate of particles formed near the sea ice surface as they get lofted to heights where clouds may form.