Tuning standalone setup of Limfjord with CMEMS boundary conditions

Coastal zones experience huge variability due to combined influence of processes in ocean, atmosphere and land. At the same time, coastal areas are important for economic, social and environmental interests such as shipping, aquaculture and mussel fisheries. Nissum Broad and Lem Vig situated in Limfjord constitute one of the finest Flatoyster environments in Europe. The FORCOAST project of Limfjord area as part of Horizon 2020 research and innovation program is dealing with Copernicus-based downstream information services incorporating CMEMS products, local monitoring data and advanced modelling. Within the FORCOAST project, downstram application for the coastal areas and estuaries of the Limfjord are developed. In this study, the Limfjord domain in about 185m horizontal resolution with wet boundaries at Baltic Sea and the North Sea is considered. Sea level and inflows in Limfjord are largely dependent on boundary conditions at North sea and Baltic sea. Therefore, a tuning of boundary conditions of standalone setup is performed by linear scaling of boundary values. The applied ocean model is the HBM model (HIROMB-BOOS Model) which is also well suited for seemless nesting at various scales enabling to model the transition from the basin-scales to coastal- and estuary-scales. Therefore, the results of standalone setup are compared with two-way nested CMEMS Baltic Monitoring Forecasting Centre set-up with included Limfjord domain. The results show that both tuned standalone setup and nested setups are able to provide high quality sea level forecast for storm surge warning, temperature, salinity and currents. The model is able to handle the shallow thermoclines in summer as well as the strong tidal and wind driven transport through narrow straits in autumn and winter. Tuning of standalone setup enables to reach comparable performance in sea level and thermodynamics as of two-way nested setup at much lower computational cost.