Optimal multiparameter analysis of source water distributions in the Southern Drake Passage

TitleOptimal multiparameter analysis of source water distributions in the Southern Drake Passage
Publication TypeJournal Article
Year of Publication2013
AuthorsFrants M., Gille ST, Hewes C.D, Holm-Hansen O., Kahru M, Lombrozo A., Measures C.I, Mitchell B.G, Wang HL, Zhou M.
JournalDeep-Sea Research Part Ii-Topical Studies in Oceanography
Date Published2013/06
Type of ArticleArticle
ISBN Number0967-0645
Accession NumberWOS:000320142000004
KeywordsAntarctic Peninsula; Bransfield strait; circulation; drake passage; indian-ocean; Iron; masses; OMP analysis; Ona Basin; phytoplankton bloom; sea; Southern Ocean; thermocline; weddell-scotia confluence

In order to evaluate the effects of horizontal advection on iron supply in the vicinity of the Shackleton Transverse Ridge (SIR) in the southern Drake Passage, the water composition in the region is estimated along the isopycnal containing the subsurface iron peak. Optimal Multiparameter (OMP) analysis of temperature, salinity, oxygen and nutrient data is used to estimate the water composition at CID stations sampled in summer 2004 and winter 2006. The highest iron concentrations in the Ona Basin are found below the mixed layer, both in summer and in winter. The water composition derived from the OMP analysis is consistent with a scenario in which iron-rich shelf waters from the South Shetland Islands and the Antarctic Peninsula are advected northward on the eastern side of the SIR, where they interact with the low-iron waters of the Antarctic Circumpolar Current (ACC) in the Ona Basin. The shelf waters and the ACC waters appear to interact through a stirring process without fully mixing, resulting in a filamented distribution that has also been inferred from the satellite data. To the west of the STR, the shelf waters are primarily confined to the continental shelf, and do not extend northwards. This source of water distribution is consistent with the idea that iron enters the Ona Basin from the continental shelf through advection along an isopycnal, resulting in an iron concentration peak occurring below the winter mixed layer in the Ona Basin. (c) 2012 Elsevier Ltd. All rights reserved.