An Updated Aerosol Simulation in the Community Earth System Model (v2.1.3): Dust and Marine Aerosol Emissions and Secondary Organic Aerosol Formation

Aerosols constitute important substance components of the Earth’s atmosphere and have a profound influence on climate dynamics, radiative properties, and biogeochemical processes. Here we introduce updated emission schemes for dust, sea-salt, and marine primary organic aerosols (MPOA), as well as augment secondary organic aerosol (SOA) formation pathways within the Community Earth System Model (CESM; version 2.1.3). The modified dust emission scheme shifts the original hotspot-like dust emission to a more continuous distribution, improving the dust aerosol optical depth (DAOD) simulations at stations in North Africa and Central Asia. This update also reduces dust residence time from 4.1 days to 1.6 days, enhancing concentration simulations downwind of dust source regions. For sea-salt emissions, we incorporate an updated sea surface temperature (SST) modulation and introduce a relative-humidity-dependent correction factor for sea-salt particle size with SST having a significantly larger impact on sea-salt emissions (16.1%) compared to the minor effect of humidity (-0.3%). We then extend to incorporate emissions of marine primary organic aerosols (MPOA) as externally mixed with sea-salt aerosols, coupled offline with ocean component Parallel Ocean Program (POP2). The results underscore the substantial influence of phytoplankton diversity on MPOA emissions, with 148% variability simulated among different phytoplankton types, highlighting the role of biological variability in aerosol modeling. Furthermore, we refine the model’s chemical mechanisms by including the irreversible aqueous uptake of dicarbonyl compounds as a new pathway for SOA formation, contributing an additional 37% to surface SOA concentrations. These improvements enrich the capability of the CESM to use intricate linkage between different components of the Earth system, thereby enabling a more comprehensive description of natural aerosol emissions, chemical processes, and their impacts.