Observations of Irminger Sea Anticyclonic Eddies

Mesoscale anticyclonic eddies in the Irminger Sea are observed using a mooring and a glider. Between 2002 and 2009, the mooring observed 53 anticyclones. Using a kinematic model, objective estimates of eddy length scales and velocity structure are made for 16 eddies. Anticyclones had a mean core dia...

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Bibliographic Details
Published in:Journal of Physical Oceanography
Main Authors: Fan, Xue, Send, Uwe, Testor, Pierre, Karstensen, Johannes, Lherminier, Pascale
Format: Article in Journal/Newspaper
Language:English
Published: Amer Meteorological Soc 2013
Subjects:
North Atlantic Ocean
Eddies
Mesoscale processes
Greenland
Irminger Sea
Norwegian Sea
Reykjanes
Cape Farewell
East Greenland
Labrador Sea
North Atlantic
Online Access:https://archimer.ifremer.fr/doc/00137/24832/22921.pdf
https://doi.org/10.1175/JPO-D-11-0155.1
https://archimer.ifremer.fr/doc/00137/24832/
Description
Summary:Mesoscale anticyclonic eddies in the Irminger Sea are observed using a mooring and a glider. Between 2002 and 2009, the mooring observed 53 anticyclones. Using a kinematic model, objective estimates of eddy length scales and velocity structure are made for 16 eddies. Anticyclones had a mean core diameter of 12 km, and their mean peak observed azimuthal speed was 0.1 m s(-1). They had core salinities and potential temperatures of 34.91-34.98 and 4.488-5.34 degrees C, respectively, making them warm and salty features. These properties represent a typical salinity anomaly of 0.03 and a temperature anomaly of 0.28 degrees C from noneddy values. All eddies had small (<< 1) Rossby numbers. In 2006, the glider observed two anticyclones having diameters of about 20 km and peak azimuthal speeds of about 0.3 m s(-1). Similar salinity anomalies were detected throughout the Irminger Sea by floats profiling in anticyclones. Two formation regions for the eddies are identified: one to the west of the Reykjanes Ridge and the other off the East Greenland Irminger Current near Cape Farewell close to the mooring. Observations indicate that eddies formed in the former region are larger than eddies observed at the mooring. A clear increase in eddy salinity is observed between 2002 and 2009. The observed breakup of these eddies in winter implies that they are a source of salt for the central gyre. The anticyclones are similar to those found in both the Labrador Sea and Norwegian Sea, making them a ubiquitous feature of the subpolar North Atlantic basins.

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