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Impacts of Sea Ice Leads on Sea Salt Aerosols in the Arctic: Results from Chemical Transport Modeling

Event Type
1310 Yeh Center
Sep 25, 2023   12:00 - 12:50 pm  
PhD Candidate Erin Emme (Advisor: Assistant Prof. Hannah Horowitz)
Originating Calendar
CEE Seminars and Conferences

Tropospheric aerosols, such as sea salt aerosol, have the potential to alter Arctic climate through aerosol direct and indirect radiative effects. However, the exact sources and processes contributing to cold season sea salt aerosol in polar regions are still under debate, preventing the improvement of polar aerosol and climate models. While the open ocean is the major accepted source of sea salt aerosols, studies suggest that open leads in sea ice could play a dominant role. Climate change has impacted the Arctic by decreasing sea ice extent and sea ice thickness, which can increase the frequency of leads. Here, we combine satellite datasets and the 3-D atmospheric chemistry transport model GEOS-Chem to investigate the pan-Arctic emissions of sea salt aerosols from open leads. Sea salt aerosol emissions from leads are calculated in GEOS-Chem using the same parameterization as open ocean emissions, scaled by the areal fraction of open leads, using the Harmonized Emissions Component (HEMCO) at the native resolution of MERRA-2 (0.5°x0.625°). Daily lead area fraction is determined from AMSR-E satellite data, for the months of November to April in years 2002 to 2008. We perform two GEOS-Chem full chemistry simulations at the highest global resolution (2°x2.5°): one with sea salt aerosol emissions for the default, open ocean + blowing snow only emissions, and the default plus lead-based emissions. HEMCO ensures the emissions at the lower resolution needed for the full chemistry simulation are of consistent magnitude with the emissions calculated at the native MERRA-2 resolution. For both cases, we simulate sea salt aerosol concentrations which we evaluate against observations and assess the impacts of additional SSA emissions on atmospheric chemistry. This includes analysis of the change in atmospheric concentrations of bromine atom (Br) and ozone.

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