Antarctic Circumpolar Transport and the Southern Mode: a model investigation of interannual to decadal time scales

Hughes, CW ORCID: 0000-0002-9355-0233, Williams, J ORCID: 0000-0002-8421-4481, Coward, AC and de Cuevas, BA (2013) Antarctic Circumpolar Transport and the Southern Mode: a model investigation of interannual to decadal time scales Ocean Science, 10 (6). pp. 2085-2107. ISSN 1812-0784

Text 2014-Hughes_et_al_OSci_Southern_Mode.pdf - Published version Download (3MB) | Preview

Abstract

Abstract. It is well-established that, at periods shorter than a year, variations in Antarctic Circumpolar Transport are reflected in a barotropic mode, known as the Southern Mode, in which sea level and bottom pressure varies coherently around Antarctica. Here, we use two multidecadal ocean model runs to investigate the behaviour of the Southern Mode at time scales on which density changes become important, leading to a baroclinic component to the adjustment. We find that the concept of a Southern Mode in bottom pressure remains valid, and remains a direct measure of the circumpolar transport, with changes at the northern boundary playing only a small role even on decadal time scales. However, at periods longer than about 5 yr, density changes start to play a role, leading to a surface intensification of the vertical profile of the transport. We also find that barotropic currents on the continental slope account for a significant fraction of the variability, and produce surface intensification in the meridional-integral flow. The role of density variations results in a sea level signal which, although reflecting transport changes at all time scales, has a ratio of sea level to transport which becomes larger at longer time scales. This means that any long-term transport monitoring strategy based on present measurement systems must involve multiplying the observed quantity by a factor which depends on frequency.

Item Type:	Article
Uncontrolled Keywords:	37 Earth Sciences, 3708 Oceanography
Depositing User:	Symplectic Admin
Date Deposited:	15 Feb 2021 08:59
Last Modified:	06 Dec 2025 05:17
DOI:	10.5194/osd-10-2085-2013
Related Websites:	Publisher
URI:	https://livrepository.liverpool.ac.uk/id/eprint/3115575
Disclaimer:	The University of Liverpool is not responsible for content contained on other websites from links within repository metadata. Please contact us if you notice anything that appears incorrect or inappropriate.