 
Summary: Scattering of barotropic Rossby waves by the
Antarctic Circumpolar Current
G. W. Owen,1
A. J. Willmott,2
and I. D. Abrahams3
Received 20 April 2005; revised 30 April 2006; accepted 13 July 2006; published 27 December 2006.
[1] This study examines the interactions between barotropic Rossby waves and a zonal
current, with particular reference to the Antarctic Circumpolar Current (ACC). In the high
latitude of the Southern Ocean, the effect, which provides the restoring mechanism for
Rossby waves, is relatively weak, resulting in barotropic waves that are extremely long,
with periods of the order of 1 week or longer. We model the interactions between the
current and the waves using the linearized potential vorticity (PV) equation with the
inclusion of background PV terms corresponding to a barotropic zonal flow of finite
width. An analytical solution is found for the simplest, piecewiselinear flow and
numerical solutions obtained for more realistic, smoothly varying flows. The results show
that, in general, the long waves are not appreciably modified or reflected by the shear flow,
except in the case where the wave is incident at an oblique angle. Wave reflection is also
more pronounced for shorter waves, such as Rossby waves having eastward group
velocity or the case where the wave frequency is just below the cutoff frequency.
Citation: Owen, G. W., A. J. Willmott, and I. D. Abrahams (2006), Scattering of barotropic Rossby waves by the Antarctic
