NEMO v4.2 in regional climate modelling - towards climate projections for the German coasts

The “German Strategy for Adaption to Climate Change” (DAS) is the political framework to climate change adaption in Germany. The DAS core service “Climate and Water” provides monitoring and projection data to evaluate requirements for climate change adaption. Using the state of the art ocean model NEMO v4.2 a setup is developed to provide projection data for the target regions North Sea and Baltic Sea with focus on the German coastal region and its estuaries.

The setup includes the entire North-West-Shelf to take into account the impact of the North Atlantic weather systems on the dynamics of the seas and the cross-shelf transport. An adjusted bathymetry based on up-to-date measurements of the sea floor from the EMODNET network is introduced and studied with regard to its tidal behaviour, especially in the German Bight. The setup is also tested for its response on the use of different data sets of boundary data for tides, temperature and salinity, providing insights into the influence of temporal resolutions of boundary data on projection results.

Validation work is presented with focus on the sea level at the German coasts and water exchange between the North Sea and the Baltic Sea through the Danish Straits. Furthermore special attention is payed to the thermal stratification and to the seasonality and thickness of sea ice.

First results and a short overview on the coupling of NEMO to the atmospheric model ICON for the EURO-CORDEX domain will complete the presentation. An outlook on further development steps towards high-resolution nested grids and the utilisation of a wetting-and-drying scheme will be given.