An updated aerosol simulation in the Community Earth System Model (v2.1.3): dust and marine aerosol emissions and secondary organic aerosol formation

Abstract. 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 develop updated emission schemes for dust, sea-salt, and marine primary organic aerosols (MPOA) and augment formation reactions for secondary organic aerosol (SOA) by introducing updated parameterizations within the Community Earth System Model (CESM; version 2.1.3). The modified 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. Also, it results in shorter dust residence time, necessary for enhancing concentration simulations downwind of dust source regions. Modifications in the sea-salt emission scheme include an update to sea surface temperature (SST) modulation and the introduction of a relative-humidity-dependent correction factor for sea-salt particle size. The effect of SST is much more significant compared to that of relative humidity. 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 influence of phytoplankton species on modeling MPOA emissions is profound, highlighting the significance of biological diversity in shaping aerosol emissions. In addition to these emission scheme improvements, we also refine the chemical mechanisms in the model. The irreversible aqueous uptake of dicarbonyl compounds is added as a new pathway for the SOA formation in the model. These improvements enrich the capability of the CESM by using ESM’s intricate linkage between different spheres of the Earth system, thereby enabling a more comprehensive description of natural aerosol emission and chemical processes and their impacts.