Effects of sea spray on large-scale climatic features over the Southern Ocean

Abstract

<p>The Southern Ocean, characterized by strong westerly winds and a rough sea state, exhibits the most pronounced<br />sea spray effects. Sea spray ejected by ocean surface waves enhances heat and water exchange at the air–sea interface.<br />However, this process has not been considered in current climate models, and the influence of sea spray on the<br />coupled air–sea system remains largely unknown. This study incorporated a parameterization of the sea spray influence on<br />latent and sensible heat fluxes into the First Institute of Oceanography Earth System Model version 2.0 (FIO-ESM v2.0), a<br />climate model coupled with an ocean surface waves component. The results indicate that the spray-mediated enthalpy flux<br />accounted for over 20%–50% of the total value. Sea spray promoted ocean evaporation and heat transport, resulting in air<br />and ocean surface cooling and strengthened westerly winds. Furthermore, a moist and stable atmosphere favored an<br />increase in cloud fraction over the Southern Ocean, particularly low-level clouds. Increased clouds reflected downward<br />shortwave radiation and reduced solar radiation absorption at the surface. At present, the climate models participating in<br />phase 6 of the Coupled Model Intercomparison Project (CMIP6) still suffer notable deficiencies in reasonably reproducing<br />the climatological features of the Southern Ocean, including warm SST and underestimated clouds biases with more<br />absorbed shortwave radiation. Our results suggest that consideration of sea spray effects is a feasible solution to mitigate<br />these common biases and enhance the confidence in simulations and predictions with climate models.</p>