He. Deswart et Jtf. Zimmerman, RECTIFICATION OF THE WIND-DRIVEN OCEAN CIRCULATION ON THE BETA-PLANE, Geophysical and astrophysical fluid dynamics, 71(1-4), 1993, pp. 17-41
A nonlinear Stommel model of the ocean circulation on the beta plane,
driven by a time periodic wind stress, is investigated in order to stu
dy symmetry properties of the observed time-mean ocean gyres. Due to t
he presence of vorticity advection terms the model will have a steady
or rectified response to fluctuating wind fields. In this paper a smal
l inverse Ekman number, ''the small beta regime'', is considered. It i
s demonstrated that for this case all qualitative features of the resi
dual circulation, obtained numerically by Veronis (1970), are reproduc
ed in an analytical way. They include the dipole character of the gyre
, its maximum symmetry breaking around the north-south axis for interm
ediate Reynolds numbers, measuring the ratio of vorticity forcing and
dissipation, and the maximum residual response for intermediate forcin
g frequencies.