Abstract
We consider results from two 27-year-long simulation pairs derived using two different ocean models. We focus on the Skagerrak/North Sea area. Each pair consists of the two terrain-following coordinate models ROMS and MIPOM. The first pair utilizes an eddy-permitting grid, that is, a grid in which the Rossby radius is barely resolved. The second pair utilizes an eddy-resolving grid in which the Rossby radius is truly resolved. The goal is to compare the quality of the two models and the two pairs. To this end we derive statistical properties such as probability density functions and compare them with similar statistics derived from observations. Thereby we obtain insight into whether a truly eddy-resolving model is required to realistically capture the mesoscale statistics. We find that eddy resolution is critical to get the mesoscale statistics correct, in particular, the strength of the current jets. Our results also indicate that the improvement gained by employing the eddy-resolving grid is mostly due to a better resolved topography. In particular, we find that this is the case in areas exhibiting prominent topographic features, such as the deep Norwegian Trench cutting into the heart of the northern North Sea/Skagerrak area. The results also highlight the advantage of first performing quality assurance investigations when implementing a new model for a new area.
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Notes
The Northern Seas encompass the Norwegian, Greenland and Iceland Seas and the adjacent Arctic and Barents Seas
r = |h(i − 1) − h(i)| / |h(i − 1) + h(i)| where h is the topography and the indices i indicate a model grid point.
As noted by Røed and Albretsen (2007) the most important fresh water source for the Norwegian Coastal Current is water originating from the Baltic Sea.
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Acknowledgements
The Torungen-Hirtshals section data was kindly made available to us by Lars Johan Naustvoll at the Institute of Marine Research Flødevigen, Arendal, Norway. Other hydrographic profile data used was made available to us through the International Council for the Exploration of the Sea (ICES) Oceanographic database. The current measurements were provided by the Norwegian Marine Data Centre, Institute of Marine Research, Bergen, Norway. We would hereby like to thank all the various contributors to these databases for allowing us to use their data. We would also like to thank two anonymous reviewers for comments that helped to improve the readability. This research was supported by the Research Council of Norway through the SKAGCOD Project No. 178322/S40 and the Norwegian Meteorological Institute. Computer time on the IBM p575+ (njord) and the Sun X2200 (titan) at the Norwegian Metacenter for Computational Science was granted by the Research Council of Norway.
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Albretsen, J., Røed, L.P. Decadal long simulations of mesoscale structures in the northern North Sea/Skagerrak using two ocean models. Ocean Dynamics 60, 933–955 (2010). https://doi.org/10.1007/s10236-010-0296-0
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DOI: https://doi.org/10.1007/s10236-010-0296-0