Mobile version

Turning around in the Lofoten eddy

Image of the Month - June 2016

Nine monthly averages of Absolute Dynamic Topography in the western Lofoten Basin. The change in color represents the seasonal variation. Each mean field has a maximum near 70°N 3°E and for each the mean position of the Lofoten Basin Eddy according to the RAFOS float is indicated by the green dot. The bathymetric contour is the 3250 m, where the Lofoten Basin eddy seems to be trapped. (Credits IMR / NOAA/NESDIS)
Map of the Nordic Seas showing the two principal pathways of warm Atlantic water (black arrows), bathymetry (blue contours with a spacing of 500 m), mean dynamic topography (shading), and salinity at 300 m depth from the high-resolution World Ocean Atlas 2013 (black contours). The Nordic Seas include the Iceland Sea, the Greenland Sea, and the Norwegian Sea with its two sub-basins the Norwegian Basin and Lofoten Basin with the large horizontal extent of Atlantic water. The Lofoten Basin deepens from east to west and exceeds 3000 m in the western half. The anticyclonic Lofoten Basin Eddy resides in the deeper parts of the basin. (Credits IMR / NOAA/NESDIS)

The Lofoten basin in the Nordic Seas is a crucial component of the Atlantic thermohaline circulation. It is fed by warm and salty North Atlantic Waters from the inner branch of the Norwegian Atlantic current. This branch goes unstable where the escarpment in bathymetry becomes exceptionally steep off the Lofoten Islands. This leads to frequent shedding of anticyclonic eddies, which then drift westward towards the interior of the Lofoten basin where they maintain the deep Atlantic Water layer structure. These eddies feed a strong anticyclonic eddy residing in the deepest part of the basin.

The anticyclonic Lofoten Basin eddy wanders about in a topographically limited region. Five surveys of the Lofoten Basin Eddy clearly reveal a well-defined coherent structure with an anticyclonically rotating core. The first nine months of a underwater float trajectory, while it was still trapped in the eddy, reveal a stably rotating core with no disruption in its orbital motion. It indicates that the core of the Lofoten Basin Eddy remains quite stable, almost immune or isolated from its interactions with the surrounding waters.

Both historical hydrographic data and altimetry now reveal that the Lofoten Basin eddy is a stable, persistent feature of the Lofoten Basin and has, quite possibly, existed for millennia. Thus, despite its small size, it plays a key role in the circulation of the Nordic Seas.

Altimetry enables to look back at phenomena for nearly 25 years now. With in situ comparisons, long-term monitoring, the ocean features are better and better known. With Jason-3 and Sentinel-3, the uninterrupted series is being continued, and new results will come from these long observations.

See also:

References:

    • H. Søiland, L. Chafik, T. Rossby, 2016: On the long-term stability of the Lofoten Basin Eddy, submitted to J. Geophys. Res.
    EnglishFrançaisEspañol
    Rss feedsContactSitemapPartnersFAQGlossaryLexiconMobile
    You must enable cookies in your browser preferences to save the modifications
    You are using an older version of Internet Explorer, please update to take full advantage of Aviso+ features

    Customize the home page

    View all widgets
    Reduce display
    Public profile
    User profile

    Select/Deselect widgets

    Discover AVISO+

    Customizable home, reading tools, products search guide, etc.. Discover step by step the features of the new site AVISO+.

    Customizable homepage

    The new home page is composed of blocks called "widgets".

    Rearrange the blocks with a "Click & Drop".

    Hide a widget with the cross at the top right. Reset or add a widget with the "wrench" icon. The "User" and "Public" profiles offer a predefined organization.

    All the modifications are automatically saved as cookies on your machine so as to enable you to have your own specific AVISO+.

    Reading tools

    Ease your reading by choosing the page background colour (black/white) and/or by modifying the font size.

    Browsing menu and breadcrum trail

    To ease your browsing through AVISO+, you can use at any time the main banner items with the interactive submenus or use the browsing menu on the left side of the screen (it is open by default). For more readiness of the page contents, you can fold and unfold the browsing menu by clicking on the tab. At any time you can know where you are thanks to the browsing menu or the breadcrum at the top of the page.

    Products search guide

    The first submenu of the "Data" banner item leads you to a new search form enabling you to find quickier the product that suits your needs. The list of results is updated according to your selection criteria.

    AVISO+ Multimedia

    The first submenu of the "Multimedia" banner item leads you to AVISO+ collections of images and videos linked to altimetry and its applications. Have a nice visit!