D. P. Marshall, D. R. Munday, L. C. Allison, R. J. Hay and H. L. Johnson, Journal of Physical Oceanography, submitted.
A reduced-gravity model of the Antarctic Circumpolar Current is formulated to identify the contributions of wind-forcing, geostrophic eddies and Sverdrup balance in setting its lateral structure and strength. Buoyancy forcing is represented through prescribed outcropping at the southern boundary and geostrophic eddies through the Gent and McWilliams eddy parameterization. Our key findings are: (i) Sverdrup balance does not set the volume transport through the model Drake Passage. (ii) A substantial circumpolar current remains when the latitude of the wind jet is shifted north of the model Drake Passage, even by several thousand kilometers. (iii) The integral of the wind stress over the circumpolar contours is a useful predictor of the magnitude of the volume transport through the model Drake Passage, although it is necessary to correct for basin-wide zonal pressure gradients in order to obtain good quantitative agreement. The model bears many similarities to that developed by Adrian Gill for a barotropic ocean, but reinterpreted in terms of contemporary descriptions of ACC dynamics. Thus, we hope to restore Gill's model to its rightful place at the center-stage of theoretical understanding of the ACC.
This manuscript is available upon request.