Publication Date:
2022-05-25
Description:
Author Posting. © The Author(s), 2013. This is the author's version of the work. It is posted here by permission of Elsevier B.V. for personal use, not for redistribution. The definitive version was published in Deep Sea Research Part II: Topical Studies in Oceanography 90 (2013): 4-14, doi:10.1016/j.dsr2.2013.03.041.
Description:
An austral winter cruise in July-August 2006 was conducted to study the winter circulation and
iron delivery processes in the Southern Drake Passage and Bransfield Strait. Results from
current and hydrographic measurements revealed a circulation pattern similar to that of the
austral summer season observed in previous studies: The Shackleton Transverse Ridge (STR) in
the southern Drake Passage blocks a part of the eastward Antarctic Circumpolar Current (ACC)
which forces the ACC to detour southward, produces a Taylor Column over the STR, and forms
an ACC jet within the Shackleton Gap, a deep channel between the STR and the shelf of
Elephant Island. Observations show that to the west of the STR, the Upper Circumpolar Deep
Water (UCDW) intruded onto the shelf around the South Shetland Islands while to the east of the
STR, shelf waters were transported off the northern shelf of Elephant Island. Along a similar
west-east transect approximately 50 km off the shelf, the northward transport of shelf waters was
approximately 2.4 and 1.2 Sv in the austral winter and summer, respectively. The waters around
Elephant Island primarily consist of the UCDW that has been modified by local cooling and
freshening, unmodified UCDW that has recently intruded onto the shelf, and Bransfield Current
water that is a mixture of shelf and Bransfield Strait waters. Weddell Sea outflows were
observed which affect the hydrography and circulation in the Bransfield Strait and indirectly
affect the circulation patterns in the southern Drake Passage and around Elephant Island. Two
Fe enrichment and transport mechanisms are proposed that intrusions of the UCDW onto the
northern shelf region of the South Shetland Islands is considered as the results of Ekman
pumping due to prevailing westerly wind in the region while the offshelf transport of shelf
waters in the shelf region east of Elephant Island is due to acquisition of positive vorticity by
shelf waters from horizontal mixing with onshelf intruded ACC waters.
Description:
This project was supported by the National Science Foundation grant numbers OPP-0229966,
ANT-0444040 and ANT-0948378 to M. Zhou, OPP0230445, ANT0443403 and ANT-0948357
to C. Measures, ANT0443869 and ANT-0948442 to M. Charette, and OPP0230443,
ANT0444134 and ANT0948338 to B.G. Mitchell.
Keywords:
Southern Ocean
;
Drake Passage
;
Antarctic Circumpolar Current
;
Shelf waters
;
Mesoscale eddies
;
Mixing
;
Iron transport
Repository Name:
Woods Hole Open Access Server
Type:
Preprint
Format:
application/pdf
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