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Direct observations of the A ntarctic S lope C urrent transport at 113°E
Author(s) -
PeñaMolino B.,
McCartney M. S.,
Rintoul S. R.
Publication year - 2016
Publication title -
journal of geophysical research: oceans
Language(s) - English
Resource type - Journals
eISSN - 2169-9291
pISSN - 2169-9275
DOI - 10.1002/2015jc011594
Subject(s) - ocean gyre , geostrophic wind , geology , barotropic fluid , continental shelf , current (fluid) , flow (mathematics) , geostrophic current , front (military) , oceanography , altimeter , current meter , geodesy , subtropics , physics , fishery , biology , mechanics
The Antarctic Slope Current (ASC), defined here as the region of westward flow along the continental slope off Antarctica, forms the southern limb of the subpolar gyres. It regulates the exchange of water across the shelf break and provides a path for interbasin westward transport. Despite its significance, the ASC remains largely unobserved around most of the Antarctic continent. Here we present direct velocity observations from a 17 month current meter moored array deployed across the continental slope between the 1000 and the 4200 m isobaths, in the southeastern Indian Ocean near 113°E. The observed time‐mean flow consists of a surface‐intensified jet associated with the Antarctic Slope Front (ASF) and a broader bottom‐intensified westward flow that extends out to approximately the 4000 m isobath and is strongest along the upper slope. The time‐mean transport of the ASC is −29.2 Sv. Fluctuations in the transport are large, typically exceeding the mean by a factor of 2. They are mainly due to changes in the northward extent of the current over the lower slope. However, seasonal changes in the wind also drive variations in the transport of the ASF and the flow in the upper slope. Both mean and variability are largely barotropic, thus invisible to traditional geostrophic methods.