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Original Research Papers

Structure and variability of the Filchner overflow plume

Authors:

E. Darelius ,

Geophysical Institute, University of Bergen, Bergen; Bjerknes Centre for Climate Research, Bergen, NO
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L. H. Smedsrud,

Bjerknes Centre for Climate Research, Bergen, NO
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S. Østerhus,

Bjerknes Centre for Climate Research, Bergen, NO
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A. Foldvik,

Geophysical Institute, University of Bergen, Bergen, NO
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T. Gammelsrød

Geophysical Institute, University of Bergen, Bergen, NO
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Abstract

Properties of the dense ice shelf water plume emerging from the Filchner Depression in the southwestern Weddell Sea are described, using available current meter records and CTD stations. A mean hydrography, based on more than 300 CTD stations gathered over 25 yr points to a cold, relatively thin and vertically well-defined plume east of the two ridges cross-cutting the continental slope about 60 km from the Filchner sill, whereas the dense bottom layer is warmer, more stratified and much thicker west of these ridges. The data partly confirm the three major pathways suggested earlier and agree with recent theories on topographic steering by submarine ridges. A surprisingly high mesoscale variability in the overflow region is documented and discussed. The variability is to a large extent due to three distinct oscillations (with periods of about 35 h, 3 and 6 d) seen in both temperature and velocity records on the slope. The oscillations are episodic, barotropic and have a horizontal scale of ∼20–40 km across the slope. They are partly geographically separated, with the longer period being stronger on the lower part of the slope and the shorter on the upper part of the slope. Energy levels are lower west of the ridges, and in the Filchner Depression. The observations are discussed in relation to existing theories on eddies, commonly generated in plumes, and continental shelf waves.

How to Cite: Darelius, E., Smedsrud, L.H., Østerhus, S., Foldvik, A. and Gammelsrød, T., 2009. Structure and variability of the Filchner overflow plume. Tellus A: Dynamic Meteorology and Oceanography, 61(3), pp.446–464. DOI: http://doi.org/10.1111/j.1600-0870.2008.00391.x
  Published on 01 Jan 2009
 Accepted on 9 Dec 2008            Submitted on 24 Jul 2008

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