Implementation of a two-way coupled atmosphere-ocean wave modeling system for assessing air-sea interaction over the Mediterranean Sea

It is generally accepted that the fluid layer surrounding Earth should be considered as a single system at short and longer spatiotemporal scales. The current knowledge on the complex mechanisms of atmosphere-ocean interactions is still insufficient. This translates to the simulation of atmosphere and ocean as a single fully coupled system constructing multi-scale, multi-model integrated modeling systems. In this study, a new two-way coupled atmosphere-ocean wave modeling system is introduced with overarching aim to thoroughly unveil the impact of waves on the sea surface roughness and the atmospheric properties. The newly developed system consists of the Weather Research Forecasting (WRF) model with Chemistry (WRF-Chem) and Hydrology (WRF-Hydro) as the atmospheric component and the Wave model (WAM) as the ocean wave component. WRF and WAM models are coupled using the OASIS Model Coupling Toolkit (OASIS3-MCT) that enables models to communicate and exchange the information required to refine their simulation results. CHAOS (Chemical Hydrological Atmospheric Ocean wave System) has been tested in a high-impact cyclonic system over the Mediterranean Sea employing one-way and two-way coupling simulations to assess the air-sea interactions, currently neglecting the chemical and hydrological capabilities. The encapsulation of the ocean waves in the atmospheric surface layer processes modifies the characteristics of atmospheric flow and determines the ocean wave generation. A remarkable finding is that the coupling of the two systems affects the air-sea momentum, enthalpy and moisture transfer determining the evolution of the cyclonic system. The interactions along the air-sea interface are also reflected in the vertical structure of troposphere and its properties. CHAOS in two-way coupling mode shows an overall improvement of the forecast skill up to 20% over the sea while positively affects the atmospheric predictability over the land.