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This article discusses the importance of lateral friction within the Western Boundary Layer (WBL) and its impact on wind stress curl. The study explores the role of nonlinear terms and the dominance of viscous terms in the boundary layer. It also examines the existence of inertial-vicious boundary layers in specific oceanic regions and the broadening effect of friction on the boundary layer. The solutions presented in the paper require consideration of the changing Coriolis parameter with latitude.
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Stommel Model: Munk Model
Munk model Lateral friction becomes important in WBL. Within the boundary layer, let , we have , Wind stress curl is the same as in the interior, becomes negligible in the boundary layer. For the lowest order, . If we let , we have . And for , . . The general solution is Since , C1=C2=0.
Total solution Using the no-slip boundary condition at x=0, .to , Western boundary current
Are nonlinear terms negligible? Given The cross-stream distance from boundary to maximum velocity is The ratio between the nonlinear and dominant viscous terms is where The continuity relation is also used: Using U=O(2 cm/s), ß=O(10-13 cm-1 s-1), AH=4106 cm2/s, we have R=4. i.e., the nonlinear terms neglected are larger than the retained viscous terms, which causes an internal inconsistency within the frictional boundary layer.
Inertial Boundary Layer If >>S and M, Given a boundary layer exists in the west where Re-scaling with , we have Conservation of potential vorticity. or
Inertial Currents with Small Friction In the presence of a small lateral friction, we can derive the perturbation equation as which makes the boundary layer possible only in the western ocean. Moreover, it can be shown that a inertial-vicious boundary layer can be generated in the northern part of the basin where characterized by a standing Rossby wave.
Assume the simple balance A parcel coming into the boundary layer has The effect of friction is reduced and the boundary layer is broadened.
Bryan (1963) integrates the vorticity equation with nonlinear term and lateral friction. The Reynolds number is define as And I/M ranges from 0.56 for Re=5 to 1.29 for Re=60. Number of undulation Increases to compensate for countercurrent
(2x10-28) Veronis (1966), nonlinear Stommel Model Both the Sverdrup and western boundary layer solutions require: 0 (f changes with latitude) Relative vorticity is small compared to f. When f, the circulation pattern becomes more symmetric with wind vorticity input balanced by frictional effect throughout the whole basin