ABSCISSA

The source of sea-salt aerosols in the Polar Regions appears to be linked to sea ice surfaces, but exact details are unclear. Defining the sources is important given the critical roles that aerosol plays in the atmosphere. For example, they contribute to the partitioning of how much sun light is scattered back to space and how much reaches the Earth surface; they affect the formation of clouds; and they host and enhance important chemical reactions.

When they are deposited on the polar ice sheets they leave a record of past conditions that can be accessed by drilling ice cores, and that holds the potential to enable reconstruction of sea ice extent in the past. It is therefore important to understand the sources of polar sea salt aerosol and to be able to predict how they may vary with, and feedback to, climate.

It was recently proposed that the main source of this polar sea-salt aerosol was the sublimation of salty blowing snow. To test this idea BAS carried out measurements in the Antarctic during a wintertime cruise in the Weddell Sea (June – August 2013). The Norwegian N-ICE 2015 ice drift expedition provided a unique opportunity to repeat the experiments in the sea ice zone of the high Arctic in winter time, where conditions are quite different compared to the Southern hemisphere. We will use the new data to derive physically-based parameterisations of sea-salt aerosol production, and use them in numerical models to test how important this source is for the Arctic and Antarctic regions.