Enhanced Organic Aerosol from Sea-spray Mitigates Global Warming (Code for simulation)

These are the model code to support our research article Enhanced Organic Aerosol from Sea-spray Mitigates Global Warming. Sea-spray primary organic aerosol (SSPOA), produced by ocean biological activity, is a key natural aerosol source that regulates marine cloud properties and climate cooling, yet its feedback is not explicitly represented in most Earth-system models. In this case, we advance a fully coupled CESM2 model by incorporating explicit SSPOA emissions, enabling paired present-day and future simulations to quantify its global climate effects. These files include four tar archive files: the model Code and Sourcemods without the SSPOA component, and the model Code and Sourcemods with the SSPOA component. We modified CESM2.1.3 to explicitly represent sea-spray primary organic aerosol (SSPOA) linked to ocean biological activity. The ocean component was extended to export surface chlorophyll from POP through the coupler, while CAM was modified to receive, store, diagnose, and optionally read/interpolate this sea-surface chlorophyll field. This chlorophyll information was passed into the sea-salt emission scheme to calculate marine organic matter aerosol emissions using chlorophyll- and wind-dependent parameterizations, with new marine organic aerosol tracers (mom_a1, mom_a2, and mom_a4) added to the modal aerosol framework. Corresponding changes were made to aerosol species registration, molecular properties, optical calculations, burden and AOD diagnostics, and history output, enabling SSPOA to affect aerosol mass, number, water uptake, optical depth, and cloud–radiation interactions. Additional code was also introduced to calculate marine isoprene emissions from biological and sea-surface microlayer processes using chlorophyll, shortwave radiation, wind speed, and sea surface temperature; however, this module was not activated in the experiments analyzed here and did not contribute to the simulated SSPOA climate effects.