Wintertime Arctic Ocean sea water properties and primary marine aerosol concentrations
1Department of Applied Environmental Science, Stockholm University, 11418 Stockholm, Sweden
2Department of Meteorology and Bert Bolin Centre for Climate Research, Stockholm University, 11418 Stockholm, Sweden
3Department of Earth Sciences, Uppsala University, 752 36 Uppsala, Sweden
4Meteorological Institute, Climate Change Unit, 00101 Helsinki, Finland
5Department of Physics, University of Helsinki, 00014 Helsinki, Finland
6TNO B&O, NL-3508 TA Utrecht, The Netherlands
Abstract. Sea spray aerosols are an important part of the climate system through their direct and indirect effects. Due to the diminishing sea ice, the Arctic Ocean is one of the most rapidly changing sea spray aerosol source areas. However, the influence of these changes on primary particle production is not known.
In laboratory experiments we examined the influence of Arctic Ocean water temperature, salinity and oxygen saturation on primary particle concentration characteristics. Sea water temperature was identified as the most important of these parameters. A strong decrease in sea spray aerosol production with increasing water temperature was observed for water temperatures between −1 °C and 9 °C. Aerosol number concentrations decreased from at least 1400 cm−3 to 350 cm−3. In general, the aerosol number size distribution exhibited a robust shape with one mode close to Dp 0.2 μm with approximately 45% of particles at smaller sizes. Changes in sea water temperature did not result in pronounced change of the shape of the aerosol size distribution, only in the magnitude of the concentrations. Our experiments indicate that changes in aerosol emissions are most likely linked to changes of the physical properties of sea water at low temperatures. The observed strong dependence of sea spray aerosol concentrations on sea water temperature, with a large fraction of the emitted particles in the typical cloud condensation nuclei size range, provide strong arguments for a more careful consideration of this effect in climate models.