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ORIGINAL RESEARCH article
Front. Mar. Sci.
Sec. Physical Oceanography
Volume 11 - 2024 |
doi: 10.3389/fmars.2024.1456207
This article is part of the Research Topic Antarctic Krill and Interactions in the East Antarctic Ecosystem View all 10 articles
Observed water-mass characteristics and circulation off Prydz Bay, East Antarctica
Provisionally accepted- 1 Institute for Marine and Antarctic Studies, University of Tasmania, Hobart, Australia
- 2 Australian Antarctic Program Partnership (AAPP), Hobart, Australia
- 3 Commonwealth Scientific and Industrial Research Organisation (CSIRO), Environment, Hobart, Australia
- 4 Norwegian Research Institute (NORCE), Bergen, Hordaland, Norway
- 5 Australian Research Council Centre of Excellence for Climate Extremes, Hobart, Australia
- 6 GLOBE Institute, Faculty of Health and Medical Sciences, University of Copenhagen, Copenhagen, Denmark
- 7 Monterey Bay Aquarium Research Institute (MBARI), Moss Landing, California, United States
- 8 Australian Antarctic Division, Hobart, Tasmania, Australia
Circulation and water masses in the greater Prydz Bay region were surveyed in the austral summer 2021 (January-March) during the 'Trends in Euphausiids off Mawson, Predators and Oceanography' (TEMPO) experiment, and are described in this paper. The Southern Antarctic Circumpolar Current Front is found in the northern part of the survey area, generally near 63-64 • S, whereas the Southern Boundary Front is located between 64 and 65.5 • S. The westward flowing Antarctic Slope Front (ASF) is found in the southern part of the survey area near the continental slope on most transects. Highest concentrations of oxygen (> 300 µmol kg -1 ) are found in shelf waters at stations in Prydz Bay, south of 67 • S along 75 • E, whereas the lowest oxygen values are found in the Circumpolar Deep Water layer, with an average of roughly 215 µmol kg -1 . North of the northern extension of the ASF, surface mixed layers are between 20 and 60 m deep. Mixed layers tend to deepen slightly in the northern part of the survey, generally increasing north of 64 • S where the ocean has been ice-free the longest. We find evidence of upwelling of waters into the surface layers, based on temperature anomaly, particularly strong along 80 • E. Enhanced variability of biogeochemical properties -nutrients, DIC, DO -in the AASW layer is driven by a combination of sea-ice and biological processes. Antarctic Bottom Water, defined as water with neutral density > 28.3 kg m 3 , was sampled at all the offshore full-depth stations, with a colder/fresher variety along western transects and a warmer/saltier variety in the east. Newly formed Antarctic Bottom Water -the coldest, freshest, and most recently ventilated -is mostly found in the deep ocean along 65 • E, in the base of the Daly Canyon.
Keywords: Southern ocean fronts, Antarctic margin, Prydz Bay Grye, water masses, Antarctic Bottom Water, carbon cycling, summer stratification, upwelling
Received: 01 Jul 2024; Accepted: 23 Aug 2024.
Copyright: © 2024 Foppert, Bestley, Shadwick, Klocker, Vives, Liniger and Westwood. This is an open-access article distributed under the terms of the Creative Commons Attribution License (CC BY). The use, distribution or reproduction in other forums is permitted, provided the original author(s) or licensor are credited and that the original publication in this journal is cited, in accordance with accepted academic practice. No use, distribution or reproduction is permitted which does not comply with these terms.
* Correspondence:
Annie Foppert, Institute for Marine and Antarctic Studies, University of Tasmania, Hobart, Australia
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