Antarctic Circumpolar Current (ACC) By: Marie McCrary

ACC Circulation: Largest wind-driven current on Earth Driven by western wind Connects the Atlantic, Pacific and Indian Oceans Moves eastward at an average of 0.5 m/s 4 km depth, km wide Transport: 134 Sv ± 10% (1) 140 Sv (2) (1)Nowlin Jr., W. D., and J. M. Klinck (1986), The physics of the Antarctic Circumpolar Current, Rev. Geophys., 24(3), 469–491, doi: /RG024i003p /RG024i003p (2)Fyfe, J and Saenko (2005), Human – Induced Change in the Antarctic Circumpolar Current, Journal of Climate, Vol 18,

ACC Circulation: Flow is strongly influenced by bottom shelf topography Shallow water (Z decreases)  curves towards equator (f decreases) Deeper water (Z increases)  curves towards pole (f increases) Conservation of potential vorticity

Sub - Antarctic Front Polar Front Southern ACC Front Variability in transport along line of constant latitude extending from the Drake Passage (10 cm/s to 50 cm/s) 75% of total transport over 20% of the cross-section Fronts Associated with ACC: Although currents are slow, transport is much greater than western boundary currents due to width and depth.

Variability of ACC Transport: Maximum transport tends to occur late winter to early spring. The heavier line is smoothed, time-averaged transport. From Whitworth (1988).

Convergence and Divergence of Ekman Transports: Divergence Leads to Upwelling of Circumpolar Deep Water Convergence leads to Downwelling of Antarctic Intermediate Water

References: Knauss, J. A., Ed. (1997). Introduction to Physical Oceanography. Long Grove, IL, Waveland Press, Inc. Stewart, R. H. (2008). Introduction To Physical Oceanography, Department of Oceanography Texas A & M University. Nowlin Jr., W. D., and J. M. Klinck (1986), The physics of the Antarctic Circumpolar Current, Rev. Geophys., 24(3), 469–491, doi: /RG024i003p /RG024i003p Fyfe, J and Saenko (2005), Human – Induced Change in the Antarctic Circumpolar Current, Journal of Climate, Vol 18,