A regional coupled ocean-atmosphere-wave model (SHYFEM-WRF-WW3) for intense meteo-marine events in the Mediterranean Sea

We are developing a new regional coupled ocean-atmosphere-wave model to study the air-sea interaction during intense meteo-marine events such as mesoscale cyclones and tropical-like cyclones. The coupled model is based on the following open-source community model components: (1) an ocean component with the SHYFEM finite element coastal ocean model, (2) a wave component with the unstructured WW3 spectral wave model, (3) an atmospheric component with the Weather Research and Forecasting model (WRF). The wave and the ocean components are hard-coupled and run on the same triangular grid. The resulting ocean-wave and atmosphere components are coupled through the Earth System Modelling Framework library (ESMF), an integrated coupling framework which leads to very clean, abstract and efficient coupled models. The implemented coupler can handle explicit and semi-implicit coupled time-stepping schemes. With this instrument we study the interaction of tropical cyclone-like vortices with the sea. We show with simplified experiments how this feedback affects the trajectories and the intensity of the vortex as well as the sea-surface temperature and the ocean circulations. We show our model scales well compared to the baseline (uncoupled) runs of the single components. It can be thus applied to large scale configurations with high resolution. We focus on a series of storm events that occurred on the Mediterranean Sea: storm Vaja in 2018, Medicane Ianos in 2020 and a mesoscale cyclone in the northern Adriatic Sea occurred in 2019.  The results derived from the coupled model are compared with those from the simulations using either only the ocean or the atmospheric model, with external forcing (uncoupled). The comparisons made against observational data show that the coupled model outperforms the uncoupled one.