Atmosphere-Ocean Feedback From Wind-Driven Sea Spray Aerosol Production

Marine aerosol production is influenced by wind speed, particularly over the Southern Ocean which is the windiest region on Earth year-round. Using climate model simulations with artificially enhanced sea spray aerosol (SSA), we show that Southern Ocean wind speeds are sensitive to SSA via surface cooling resulting from enhanced aerosol concentrations. The near-surface westerly jet weakens, therefore reducing SSA production. Comparing coupled and atmosphere-only simulations indicates that SSA partially regulates its own production via a feedback between the atmosphere and ocean. The decrease in radiative forcing in the coupled model is approximately one-quarter of that simulated by the atmosphere-only model, and the extent of the feedback also depends on the SSA source function used. Our results highlight the importance of understanding SSA emissions and their parameterization in climate models. Including a temperature dependence in SSA parameterizations can play a large role in the climate feedback, but further investigation is needed.