A Coupled Model Study on the Formation and Dissipation of Sea Fogs

Abstract

This study examined the impact of air?sea coupling using a coupled atmosphere?ocean modeling system consisting of the Coupled Ocean?Atmosphere Mesoscale Prediction System as the atmospheric component and the Regional Ocean Modeling System as the oceanic component. Numerical experiments for advection and steam fog events were carried out to clarify the modulation of the formation and dissipation of sea fogs by the air?sea temperature difference (air temperature minus sea surface temperature) and the atmospheric stability. The coupled simulation showed that advection fog is obviously controlled by low-level atmospheric stability and downward latent heat flux with oceanic cooling through air?sea coupling. In particular, air?sea coupling stabilizes the low-level atmosphere at the dissipation stage, and then suppresses vertical mixing, which retards the dissipation of advection fog. In the case of a steam fog event, the upward turbulent heat fluxes are increased significantly from the formation time to the mature time. A decrease in sea surface temperature cools the low-level atmosphere, which increases the condensation rate and low-level atmospheric stability, eventually retarding the dissipation of steam fog.