Royal Netherlands Institute for Sea Research
Royal Netherlands
Institute for Sea Research

Regional Ocean Modeling System

At NIOZ, we use hydrodynamic models to study sea-level change. In particular, we are using the Regional Ocean Modeling System (ROMS), which is a free-surface, primitive equations ocean model with terrain-following coordinates (Shchepetkin & McWillams, 2005). In simple words, ROMS is a software package that can be used to solve the equations of motions for the ocean.

A regional configuration of ROMS for the Northwestern European Shelf. Figure: Tim Hermans

Regional configuration

Together with Dewi Le Bars at the KNMI, we have developed a regional configuration of ROMS for the Northwestern European Shelf and the surrounding ocean with a resolution of 1/8 by 1/8°. This region includes shallow marginal seas such as the North Sea, Celtic Sea and Irish Sea. By providing the model with lateral ocean boundary conditions and atmospheric surface forcing, it is possible to simulate the state of the ocean forward in time.

The simulation gives us information about the changes in the ocean’s temperature, salinity and currents, but also the height of the sea surface. This allows us to understand better how the sea level will change in the future, but also how the sea level has changed in the past. Currently, we are using ROMS to explain the drivers of the interannual sea-level variability on the Northwestern European Shelf that has been observed with satellite altimetry over the past 25 years.


Shchepetkin, A. F., & McWillams, J. C. (2005). The regional oceanic modeling system (ROMS): a split-explicit, free-surface, topography-following-coordinate oceanic model. Ocean Modelling, 9, 347–404.