Effects of Bottom Topography and Density Stratification on Variations of Western Boundary Currents Caused by Periodic Change in Wind Stress

Abstract

Variations of the western boundary currents induced by a periodic change in windstress are studied in a two-layer model with a continental slope along the western boundary.The variation of the total transport of the western boundary current over the continental slopeshows a considerable phase lag with the wind stress and a decrease in amplitude comparedwith for the flat bottom ocean, though the interior barotropic response is to adjust almostinstantaneously to the wind stress. The total transport variation of the western boundarycurrent is well approximated by the upper layer transport variation. That is, almost completeseparation of the upper- and lower-layer flows takes place over the slope, and only the upperlayer flow contributes to the change in total transport of the western boundary current.Contributions of the interior barotropic and baroclinic responses to the upper layer transportvariation depend on the forcing period. With decrease in the forcing period, the barotropicresponse becomes relatively important for determining the upper layer transport variationalthough the amplitude of the variation is smaller.