Quantifying mesoscale eddies in the Lofoten Basin

The Lofoten Basin is the most eddy rich region in the Norwegian Sea. In this paper, the characteristics of these eddies are investigated from a comprehensive database of nearly two decades of satellite altimeter data (1995–2013) together with Argo profiling floats and surface drifter data. An automa...

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Bibliographic Details
Published in:Journal of geophysical research. Oceans 2016-07, Vol.121 (7), p.4503-4521
Main Authors: Raj, R. P., Johannessen, J. A., Eldevik, T., Nilsen, J. E. Ø., Halo, I.
Format: Article
Language:English
Subjects:
Altimeters
Altimetry
Argo floats
Automation
Barotropic mode
Basins
Biomass
Brackish
Current rings
Drift
Drifters
Eddies
Energy
Energy conversion
Energy transfer
Floats
Geophysics
Lofoten Basin
Marine
Mesoscale eddies
Mesoscale phenomena
Norwegian Atlantic Slope Current
Ocean basins
Ocean circulation
Profiles
Profiling
Satellite altimetry
Satellites
Slope currents
Slopes
Spatial distribution
Surface drifters
Vertical profiles
Vortices
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Summary:The Lofoten Basin is the most eddy rich region in the Norwegian Sea. In this paper, the characteristics of these eddies are investigated from a comprehensive database of nearly two decades of satellite altimeter data (1995–2013) together with Argo profiling floats and surface drifter data. An automated method identified 1695/1666 individual anticyclonic/cyclonic eddies in the Lofoten Basin from more than 10,000 altimeter‐based eddy observations. The eddies are found to be predominantly generated and residing locally. The spatial distributions of lifetime, occurrence, generation sites, size, intensity, and drift of the eddies are studied in detail. The anticyclonic eddies in the Lofoten Basin are the most long‐lived eddies (>60 days), especially in the western part of the basin. We reveal two hotspots of eddy occurrence on either side of the Lofoten Basin. Furthermore, we infer a cyclonic drift of eddies in the western Lofoten Basin. Barotropic energy conversion rates reveals energy transfer from the slope current to the eddies during winter. An automated colocation of surface drifters trapped inside the altimeter‐based eddies are used to corroborate the orbital speed of the anticyclonic and cyclonic eddies. Moreover, the vertical structure of the altimeter‐based eddies is examined using colocated Argo profiling float profiles. Combination of altimetry, Argo floats, and surface drifter data is therefore considered to be a promising observation‐based approach for further studies of the role of eddies in transport of heat and biomass from the slope current to the Lofoten Basin. Key Points The mesoscale eddies in the Lofoten Basin are predominantly generated and residing locally The anticyclonic eddies are the most long‐lived eddies in the Lofoten Basin Energy is transferred from the slope current to the mesoscale eddies
ISSN:2169-9275
2169-9291
DOI:10.1002/2016JC011637