Meridional displacement of the Antarctic Circumpolar Current

• Published in: Philosophical Transactions of the Royal Society A: Mathematical, Physical and Engineering Sciences
• Main Author: Gille, Sarah T.
• Format: Article in Journal/Newspaper
• Language: English
• Published: The Royal Society 2014
• Subjects: Antarctic; Southern Ocean; The Antarctic; Antarc*
• Online Access: http://dx.doi.org/10.1098/rsta.2013.0273; https://royalsocietypublishing.org/doi/pdf/10.1098/rsta.2013.0273; https://royalsocietypublishing.org/doi/full-xml/10.1098/rsta.2013.0273

Observed long-term warming trends in the Southern Ocean have been interpreted as a sign of increased poleward eddy heat transport or of a poleward displacement of the entire Antarctic Circumpolar Current (ACC) frontal system. The two-decade-long record from satellite altimetry is an important source of information for evaluating the mechanisms governing these trends. While several recent studies have used sea surface height contours to index ACC frontal displacements, here altimeter data are instead used to track the latitude of mean ACC transport. Altimetric height contours indicate a poleward trend, regardless of whether they are associated with ACC fronts. The zonally averaged transport latitude index shows no long-term trend, implying that ACC meridional shifts determined from sea surface height might be associated with large-scale changes in sea surface height more than with localized shifts in frontal positions. The transport latitude index is weakly sensitive to the Southern Annular Mode, but is uncorrelated with El Niño/Southern Oscillation.