Southern Ocean fronts from the Greenwich meridian to Tasmania

Abstract

All available meridional sections have been analyzed to investigate the evolution of main fronts between 0 ø and 150øE. more complex in the African sector as the Agulhas Retroflection and the bottom topography force a more convoluted pattern. The Retroflection and associated Agulhas Front (AF) press the SSTF from 38 ø to 42ø-43øS. Strong interactions of the AF, SSTF, and SAF with topography shift the fronts but do not obliterate them. The AF can be traced reliably up to 52øE, sometimes up to 75øE. The SAF is deflected from 45 ø to 43øS by the Mid-Ocean Ridge and converges with the SSTF north of the Prince Edward Islands to form a combined SSTF/SAF. This front intensifies east of 50ø-52øE as a result of the confluence with the AF, and between 52 ø and 65øE a triple AF/SSTF/SAF ("the Crozet Front") is observed. The PF continues along 49 ø and 50øS between the Crozet Plateau and the Ob-Lena (Conrad) Rise, passing north of Kerguelen, nearly joining the triple Crozet Front. Downstream of the Kerguelen-Amsterdam Passage the canonical structure is being restored (SSTF, SAF, PF); however, the front parameters in the Australian sector are different from the African sector, largely because of strong air-sea interaction and cross-frontal exchanges in the Crozet-Kerguelen region. The SSTF, squeezed between the AF and SAF, loses characteristics to both. The SSTF/SAF interaction results in the Australian SAF being warmer and saltier downstream, while the SSTF becomes shallower and weaker. The Australian STF derives its characteristics mostly from the AF, thus bringing the modified Agulhas waters' to the Pacific Ocean. The newly def'med North Subtropical Front (NSTF) was distinguished in the Indian Ocean between 31ø and 38øS. The front marks the southern boundary of the subtropical salty, warm water pool of the central South Indian Ocean. The NSTF location is coincident with the position of the wind convergence between westerlies and easterlies, suggesting the possible wind-driven frontogenesis.

Polar stratification: A critical view from the Southern Ocean

“…In our study, we use contents of opal and biogenic barium (Ba bio ) and MAR Opal for a semi-quantitative Belkin and Gordon, 1996; thin line), the modern summer sea-ice coverage (light-grey shaded), and the sea-ice edges for modern winter (dashed line), LGM summer (bold line) and LGM winter (dotted line) according to Gersonde et al (2005). The area between the modern summer and winter sea-ice edges delineates the present seasonal ice zone (SIZ) and the area between the modern winter sea-ice edge and the APF delineates the modern permanent open-ocean zone (POOZ).…”

The US Southern Ocean Joint Global Ocean Flux Study: an introduction to AESOPS

“…The Southern Ocean is traditionally divided into concentric zones surrounding Antarctica. From north to south these are the Subantarctic Zone, lying between the Subtropical Front (STF) and the Subantarctic Front (SAF), the Polar Front Zone, located between the SAF and the Polar Front (PF), and the Antarctic Zone, encompassing all waters south of the PF (although some authors distinguish continental shelf waters as a separate zone; e.g., Nowlin and Klink, 1986;Patterson and Whitworth, 1990;Peterson and Strama, 1991;Orsi et al, 1995;Belkin and Gordon, 1996). The Seasonal Ice Zone (TreH guer and Jacques, 1992) overlaps the Antarctic Zone, and extends to ca.…”

Accumulation and uptake of anthropogenic CO2 in the Southern Ocean, south of Australia between 1968 and 1996

“…Dissolved oxygen was determined using (Figure 2a). Farther south, the subantarctic Front (SAF) is generally defined by the maximum temperature gradient in the range 3ø-8øC at 100-400 m depth [Belkin and Gordon, 1996]. The SAF is usually located at about 50ø-51øS along the SR3 line .…”