Sea-level rise poses severe threats to coastal and low-lying regions around the world, by exacerbating coastal erosion and flooding. Adequate sea-level projections over the next decades are important for both decision making and for the development of successful adaptation strategies in these coastal and low-lying regions to climate change. ocean components of climate models used in the most recent sea-level projections do not explicitly resolve ocean mesoscale processes. Only a few effects of these mesoscale processes are represented in these models, which leads to errors in the simulated properties of the ocean circulation that affect sea-level projections. Using the Caribbean Sea as an example region, we demonstrate a strong dependence of future sea-level change on ocean model resolution in simulations with a global climate model. the results indicate that, at least for the Caribbean Sea, adequate regional projections of sea-level change can only be obtained with ocean models which capture mesoscale processes. The ongoing increase of global sea level threatens both coastal and low-lying regions. The combination of future sea-level rise with increasing storm occurrence and intensity may exacerbate beach erosion 1. This can have severe consequences for areas which are highly dependent on their beaches, either for flood safety or economically for local tourism 2,3. Higher sea levels can also lead to changes in coastal ecosystems, and permanent submergence of land and human settlements 4. For making adequate decisions on the development of successful adaptation strategies to sea-level rise, skillful projections over the next decades are crucially important 5. By decomposing the components contributing to the satellite-observed global mean sea-level (GMSL) rise between 1993 and 2014, it was shown that the dominant contributor to GMSL is thermal expansion of the ocean 6. Over the same period, the contribution of mass loss of both glaciers and large ice sheets to GMSL rise became more important over time 6,7. On a regional scale, sea-level rise may deviate from GMSL rise 8 and can be caused by other processes than thermal expansion. For example, the dominant contributor to sea-level rise in the Caribbean is thermal expansion (40% = 0.8 mm year −1) while east of the Caribbean 9 this is ocean mass redistribution (50% = 1.7 mm year −1). Regional sea-level change induced by variations in the gravitational contribution due to large ice sheets and glacial isostatic adjustment is very homogeneous over these two regions 9. Hence, the difference in magnitude of sea-level rise in the different regions is caused by ocean sterodynamic effects (i.e. mass redistribution and thermal expansion) 10. Ocean volume conserving climate models, such as those used in the sixth coupled model inter-comparison projects (CMIP) of the Intergovernmental Panel on Climate Change (IPCC) Assessment Report, provide projections of the dynamic sea level (DSL) and sterodynamic sea level (SDSL) 22. Due to their low spatial resolution, the ocean component ...

Ice induced variability of tides in the Canadian Arctic Archipelago, including Baffin Bay and Hudson Strait/Hudson Bay system, was studied by means of a new high resolution tidal model. Here we show that the seasonal variations of the tidal constants are significant in the major part of the domain. Month to month changes of the tidal phases can reach 180 degrees due to changes in the number and positions of the amphidromic points, whereas the amplitude variations are especially large in the near resonant basins. We also show that the tidal seasonality has undergone dramatic changes in the past decades due the decaying extent of the Arctic sea ice. These seasonal/decadal scale changes not only vary tidal dissipation on the shelf, but also impact tides in the adjacent open ocean and, therefore, cannot be neglected.

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In this paper, we focus on a conservative momentum advection discretisation in the presence of zlayers. While in the 2D case conservation of momentum is achieved automatically for an Eulerian advection scheme, special attention is required in the multi-layer case. We show here that an artificial vertical structure of the flow can be introduced solely by the presence of the z-layers, which we refer to as the staircase problem. To avoid this staircase problem, the z-layers have to be remapped in a specific way. The remapping procedure also deals with the case of an uneven number of layers adjacent to a column side, thus allowing one to simulate flooding and drying phenomena in a 3D model.

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