Bounding the contribution of open leads to sea spray aerosol emissions in the high Arctic

In the Arctic ocean, open leads have the ability to release sea spray into the atmosphere. However, the magnitude and seasonality of this flux are relatively unknown, which is a limitation to our understanding of the polar climate. Most atmospheric models do not include sea spray from leads, because of the lack of existing parameterization. In this work we propose a parameterization for sea spray fluxes from open leads in the Arctic, which leverages aerosol flux measurements from a past campaign combined with the latest generation of sea ice modeling.

Based on our parameterization, the annual total emitted mass of sea salt from open leads, [0.1–1.5] Tg/yr, is comparable to emissions from blowing snow and to the transported mass of sea salt from open ocean coming from the lower latitudes. Furthermore, the seasonality of open lead and blowing snow sea salt emissions have opposite phases, and their spatial distribution across the Arctic is also different. Therefore, we find that including both open lead and blowing snow sea salt fluxes can improve the reproduction of the annual cycle of sea salt aerosol atmospheric concentration at high latitude stations.

Using sea ice concentration fields from the neXtSimv2 sea ice model and implementing our parameterization in the WRF-Chem chemistry-transport model, we evaluate the impacts of open lead emissions on sea salt concentrations and clouds in the high Arctic.