Spatial and Subannual Variability of the Antarctic Slope Current in an Eddying Ocean–Sea Ice Model
- 1 March 2022
- journal article
- research article
- Published by American Meteorological Society in Journal of Physical Oceanography
- Vol. 52 (3), 347-361
- https://doi.org/10.1175/jpo-d-21-0143.1
Abstract
The Antarctic Slope Current (ASC) circumnavigates the Antarctic continent following the continental slope and separating the waters on the continental shelf from the deeper offshore Southern Ocean. Water mass exchanges across the continental slope are critical for the global climate as they impact the global overturning circulation and the mass balance of the Antarctic ice sheet via basal melting. Despite the ASC’s global importance, little is known about its spatial and subannual variability, as direct measurements of the velocity field are sparse. Here, we describe the ASC in a global eddying ocean–sea ice model and reveal its large-scale spatial variability by characterizing the continental slope using three regimes: the surface-intensified ASC, the bottom-intensified ASC, and the reversed ASC. Each ASC regime corresponds to a distinct classification of the density field as previously introduced in the literature, suggesting that the velocity and density fields are governed by the same leading-order dynamics around the Antarctic continental slope. Only the surface-intensified ASC regime has a strong seasonality. However, large temporal variability at a range of other time scales occurs across all regimes, including frequent reversals of the current. We anticipate our description of the ASC’s spatial and subannual variability will be helpful to guide future studies of the ASC aiming to advance our understanding of the region’s response to a changing climate. The Antarctic Slope Current (ASC) circumnavigates the Antarctic continent following the continental slope and separating the waters on the continental shelf from the deeper offshore Southern Ocean. Water mass exchanges across the continental slope are critical for the global climate as they impact the global overturning circulation and the mass balance of the Antarctic ice sheet via basal melting. Despite the ASC’s global importance, little is known about its spatial and subannual variability, as direct measurements of the velocity field are sparse. Here, we describe the ASC in a global eddying ocean–sea ice model and reveal its large-scale spatial variability by characterizing the continental slope using three regimes: the surface-intensified ASC, the bottom-intensified ASC, and the reversed ASC. Each ASC regime corresponds to a distinct classification of the density field as previously introduced in the literature, suggesting that the velocity and density fields are governed by the same leading-order dynamics around the Antarctic continental slope. Only the surface-intensified ASC regime has a strong seasonality. However, large temporal variability at a range of other time scales occurs across all regimes, including frequent reversals of the current. We anticipate our description of the ASC’s spatial and subannual variability will be helpful to guide future studies of the ASC aiming to advance our understanding of the region’s response to a changing climate.Keywords
Funding Information
- Australian Research Council, Discovery Project (DP190100494)
- Australian Research Council, DECRA Fellowship (DE170100184)
- Australian Research Council, Discovery Project (DP190100494.)
- Australian Research Council, Discovery Project (DP190100494.)
This publication has 36 references indexed in Scilit:
- On the Role of Coastal Troughs in the Circulation of Warm Circumpolar Deep Water on Antarctic ShelvesJournal of Physical Oceanography, 2013
- Sensitivity of Circumpolar Deep Water Transport and Ice Shelf Basal Melt along the West Antarctic Peninsula to Changes in the WindsJournal of Climate, 2012
- Two years of oceanic observations below the Fimbul Ice Shelf, AntarcticaGeophysical Research Letters, 2012
- Modelling the seasonal variability of the Antarctic Slope CurrentOcean Science, 2011
- Observations of the Antarctic Slope Undercurrent in the southeastern Weddell SeaGeophysical Research Letters, 2010
- Seasonal variability of the Antarctic Coastal Current and its driving mechanisms in the Weddell SeaDeep Sea Research Part I: Oceanographic Research Papers, 2009
- A model for the structure of the Antarctic Slope FrontDeep Sea Research Part II: Topical Studies in Oceanography, 2009
- Western Ross Sea continental slope gravity currentsDeep Sea Research Part II: Topical Studies in Oceanography, 2009
- Bottom water production and its links with the thermohaline circulationAntarctic Science, 2004
- On the nature and significance of the Antarctic Slope FrontMarine Chemistry, 1991