Aachal successfully defended her MS Thesis on October 3. Her Thesis “Projecting Future Arctic Tropospheric Ozone and Mercury” studied how warming temperatures and falling sea ice concentrations in the Arctic affect atmospheric chemistry and transport. She modified the GEOS-Chem model to simulate present-day and future (2040s) conditions and added model diagnostics to understand the causes of those changes.
Aachal’s results predict that reactive halogen concentrations are likely to decrease in the boundary layer, leading to increased near-surface ozone and reduced mercury deposition to the surface. The halogen changes are due to a complex interplay of surface sources and heterogeneous atmospheric chemistry. Decreases in sea ice reduce the halogen sources from snowpack photochemistry and blowing snow, while the increase in open water increases sea salt aerosol production, with reductions being more important overall.