The North Atlantic subpolar circulation in an eddy-resolving global ocean model

The subpolar North Atlantic represents a key region for global climate, but most numerical models still have well-described limitations in correctly simulating the local circulation patterns. Here, we present the analysis of a 30-year run with a global eddy-resolving (1/12°) version of the NEMO ocea...

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Bibliographic Details
Published in:Journal of marine systems 2015-02, Vol.142, p.126-143
Main Authors: Marzocchi, Alice, Hirschi, Joël J.-M., Holliday, N. Penny, Cunningham, Stuart A., Blaker, Adam T., Coward, Andrew C.
Format: Article
Language:English
Subjects:
Circulation
Computer simulation
Density
Eddy-resolving
Gyres
Labrador
Marine
Mathematical models
NEMO
North Atlantic
Ocean modelling
Ocean models
Physical oceanography
Subpolar gyre warming
Winter
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Summary:The subpolar North Atlantic represents a key region for global climate, but most numerical models still have well-described limitations in correctly simulating the local circulation patterns. Here, we present the analysis of a 30-year run with a global eddy-resolving (1/12°) version of the NEMO ocean model. Compared to the 1° and 1/4° equivalent versions, this simulation more realistically represents the shape of the Subpolar Gyre, the position of the North Atlantic Current, and the Gulf Stream separation. Other key improvements are found in the representation of boundary currents, multi-year variability of temperature and depth of winter mixing in the Labrador Sea, and the transport of overflows at the Greenland–Scotland Ridge. However, the salinity, stratification and mean depth of winter mixing in the Labrador Sea, and the density and depth of overflow water south of the sill, still present challenges to the model. This simulation also provides further insight into the spatio-temporal development of the warming event observed in the Subpolar Gyre in the mid 1990s, which appears to coincide with a phase of increased eddy activity in the southernmost part of the gyre. This may have provided a gateway through which heat would have propagated into the gyre's interior. •We analyse the performance of a 1/12° ocean model in the subpolar North Atlantic.•Results are presented and validated against observations in the Subpolar Gyre.•This model shows significant improvements from its coarser resolution versions.•This simulation provides insight into the mid 1990s Subpolar Gyre warming event.
ISSN:0924-7963
1879-1573
DOI:10.1016/j.jmarsys.2014.10.007