Structure and formation of anticyclonic eddies in the Iceland Basin
Bower, Amy S.
MetadataShow full item record
The Iceland Basin has the most energetic eddy activities in the subpolar North Atlantic. This study documents the structure for an anticyclonic eddy in the Iceland Basin using high‐resolution hydrographic and velocity observations. The eddy core waters have lens‐like structure with warm and salty features in the upper 1,000 m. The eddy distorts the density surface by doming the upper isopycnals and deepening the ones near the permanent pycnocline. The eddy has a diameter of about 120 km with substantial barotropic component in the velocity profiles. One branch of the North Atlantic Current in the central Iceland Basin is superimposed onto the eddy, leading to asymmetric velocity structure. Satellite maps show that eddy first shows up over the western slope of the Hatton Bank and moves westward to the central Iceland Basin. The waters enclosed in the eddy core share the same properties with Subpolar Mode Waters. Similar anticyclonic eddies are also found in high‐resolution numerical model simulations, which is used to explore eddy formation. The model results reveal that the potential vorticity gradient prior to the eddy event change signs in both horizontal and vertical directions. This potential vorticity gradient structure meets the necessary condition for the barotropic and baroclinic instabilities. Further calculation of the energy conversions suggests that eddies extract mean potential energy from the large‐scale isopycnal slope and gain the mean kinetic energy in the upper ocean. Therefore, both barotropic and baroclinic instabilities are involved to support the eddy growth.
Author Posting. © American Geophysical Union, 2018. This article is posted here by permission of [publisher] for personal use, not for redistribution. The definitive version was published in Journal of Geophysical Research: Oceans 123 (2018): 5341-5359, doi:10.1029/2018JC013886.
Suggested CitationJournal of Geophysical Research: Oceans 123 (2018): 5341-5359
Showing items related by title, author, creator and subject.
Ullgren, Jenny E.; Fer, Ilker; Darelius, Elin; Beaird, Nicholas (John Wiley & Sons, 2014-01-10)The narrow and deep Faroe Bank Channel (FBC) is an important pathway for cold, dense waters from the Nordic Seas to flow across the Iceland-Scotland ridge into the North Atlantic. The swift, turbulent FBC overflow is ...
Pickart, Robert S.; Spall, Michael A.; Torres, Daniel J.; Våge, Kjetil; Valdimarsson, Héðinn; Nobre, Carolina; Moore, G. W. K.; Jonsson, Steingrimur; Mastropole, Dana M. (Sears Foundation for Marine Research, 2017-09-01)Shipboard hydrographic and velocity sections are used to quantify aspects of the North Icelandic Jet (NIJ), which transports dense overflow water to Denmark Strait, and the North Icelandic Irminger Current (NIIC), which ...
Variability of the Iceland‐Scotland overflow water transport through the Charlie‐Gibbs fracture zone : results from an eddying simulation and observations Xu, Xiaobiao; Bower, Amy S.; Furey, Heather H.; Chassignet, Eric P. (John Wiley & Sons, 2018-08-20)Observations show that the westward transport of the Iceland‐Scotland overflow water (ISOW) through the Charlie‐Gibbs Fracture Zone (CGFZ) is highly variable. This study examines (a) where this variability comes from and ...