Influence of oceanic mesoscale eddy on the atmospheric boundary layer based on an idealized model

Abstract

Often, numerical models rely on parameterization schemes to represent currently unresolved or insufficiently understood phenomena.The influence of ocean mesoscale eddies on the overlying atmosphere is such a phenomenon. Using the Weather Research and Forecasting (WRF) model, the Regional Ocean Modeling System (ROMS) and the Coupled Ocean-Atmosphere-Wave-Sediment Transport (COAWST) modelling system, this study investigates the influence of idealized oceanic mesoscale eddies on the atmospheric boundary layer (ABL). The idealized model is horizontally homogeneous and set on an f-plane at 35°N. The cyclonic (anticyclonic) eddy causes sea level pressure (SLP) to increase (decrease) and reduces (increases) latent and sensible heat fluxes, surface winds, marine ABL, and atmospheric precipitable water in the coupled and uncoupled cases. Moreover, a momentum budget analysis of the model output shows that the pressure gradient term is the primary contributor to atmospheric momentum balance. Additionally, it should be noted that the SLP adjustment mechanism is important when advection is weak. Comparing the uncoupled and coupled WRF cases, the eddy's effect on atmospheric parameters is more intense in the uncoupled than in the coupled case, which can increase precipitation by 50% and wind speed and heat flux by 20–30%. These results may be potentially important for future parameterizations of mesoscale air-sea interaction processes in numerical model development.