文档介绍:Deep-Sea Research1, Vol. 40, No. 11/12, pp. 2243-2257, 1993. 09674)637/93 $6./1(I +
Printed in Great Britain. © 1993 Pergamon Press Ltd
The/]-induced drift of separated boundary currents
DORON NOF*
(Received 26 October 1992; in revised form 15 April 1993; accepted 15 April 1993)
Abstract--Western boundary currents flow poleward from low latitudes until they ultimately
separate from the coast and turn eastward into the ocean interior. The separation is mainly due to
either: (i) the variation of the Coriolis parameter with latitude (8) which causes vanishing of the
near-wall depth; (ii) vanishing wind stress curl over the ocean interior which forces zero meridional
transport; or (iii) opposing currents that flow toward the equator and force the northward flowing
currents to turn offshore (AGRA and NOF, Deep Sea Research I, 40, 2259-2282). Here, we focus on
the third kind of separated currents and show that, due to fl, such separated currents migrate along
the wall. A nonlinear "reduced gravity" one-and-a-half layer model is used to compute the desired
migration speed. Solutions of the primitive equations are constructed analytically assuming that
the translation rate is steady. It is found that the migration rate along the wall is given by flRea
cosa/2 sinT, where R d is the Rossby radius, a an angle that measures the inclination of the joint
offshore currents relative to the north, and 7 is the angle between the axis of the joint offshore
currents and the wall. The migration meridional component can be either northward or southward
(depending on the inclination of the wall) but the zonal component is always westward. When the
separated joint offshore flow i