XBT Analysis - Antarctic Circumpolar Current variability at ~0°E

The Antarctic Circumpolar Current (ACC) is a major conduit for interoceanic exchange of heat and salt. The variability of this current is largely determined by the individual behavior of the ACC fronts, from which the Subantarctic Front (SAF) and the Antarctic Polar Front (APF) are the main contributors. The importance of monitoring the ACC variability resides in that this current plays an important role on processes of global relevance, such as in the rate of water mass formation, and in the Meridional Overturning Circulation.

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The Subantartic Front and Antarctic Polar Front

Location of the AX25 realizations, which were used to compute the variability of the ACC fronts at 0°E, overlaid on the (left) Mean Dynamic Topography, and (right) Mean Geostrophic Velocity from the MDT_CNES-CLS09 climatology. The mean location of the Subantarctic Front (SAF), and of the Antarctic Polar Front (APF) are highlighted.

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Baroclinic velocity and Frontal transports variability

(reference level = 800m)

(upper-left) Mean baroclinic geostrophic velocity above 800 m computed using 15 AX25 realizations, and its (upper-right) standard deviation. The eastward flow associated with the Subantarctic Front (SAF) and Antarctic Polar Front (APF) are highlighted. (lower) Time-series for the integrated SAF and APF volume transport accross AX25 (1 Sv = 106m3s-1). The reference level adopted is at 800 m.

The temperature variability accross the Brazil Current front at 34°S can be found here>>

The XBT data along AX25 can be obtained here>>

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References

Domingues, R., G. J. Goni, S. Swart, and D. Dong, 2014. Atmospherically forced variability of the Antarctic Circumpolar Current south of Africa between 1993 - 2010, J. Geophys. Res. Doi: 10.1016/j.csr.2013.12.009. [PDF]

Swart, S., S. Speich, I.J. Ansorge, G.J. Goni, S. Gladyshev, and J.R.E. Lutjeharms, 2008: Transport and variability of the Antarctic Circumpolar Current south of Africa. J. Geophys. Res., 113(C9):C09014, doi:10.1029/2007JC004223. [PDF]

Ansorge I., S. Speich, J. Lutjeharms, G. Goni, C. Rautenback, P. Froneman and S. Garzoli, 2005: Monitoring the oceanic flow between Africa and Antarctica: Report of the first Good Hope cruise. South African. J. Sci., 101(3-4):29-35. [PDF]

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Acknowledgments

The Mean Dynamic Topography and Mean Geostrophic Velocity fields are from the MDT_CNES-CLS09 climatology produced by CLS Space Oceanography Division and distributed by AVISO, with support from CNES.