Sea Surface Temperature (SST) Dependence of Sea Salt (SS) Emissions - Physical Explanations and Implications for SS Mediated Climate Feedback

This study is motivated by the potential implications for climate feedbacks from sea salt aerosols (SSA), suggested by recent formulations of SS emission that consider the direct dependency of sea surface temperature (SST) on SS emission. This temperature dependency impacts the magnitude and scale of the potential negative radiative effect SSA has on the climate, which translates to reductions in global climate model (GCM) climate sensitivity. In GFDL's Earth System Model Version 4.1 (ESM-4), the inclusion of the SST dependency in SS emission results in lower climate sensitivity by producing a negative climate feedback of approximately -0.125 W m2 K-1 (Paulot et al. 2020). However, if SS emission does not directly depend on SST but rather on other factors which co-vary with SST, then the magnitude and nature of SSA-mediated climate feedbacks will differ. Analyzing the differences between observed and modeled SSA concentrations, we find that mechanisms other than intrinsic dependence of SS emissions on temperature are possible. Convective gustiness is a potential physical mechanism relevant for SSA production that covaries with temperature. If further analysis confirms convective gustiness can explain differences between observed and modeled SSA concentrations, it will be important to account for it in GCM SSA production parameterizations.