The adjustment of a shelfbreak jet to cross-shelf topography

A rigid-lid, finite-difference numerical model is used to study the adjustm ent of inviscid, along-shelf, barotropic shelfbreak jets to cross-shelf, ch annel topography. The channel is embedded in the shelf topography perpendic ularly to the shelfbreak, the shelfbreak jet flows with the direction of pr opagation of long-wavelength, topographic Rossby waves, and the coast is su fficiently distant so as not to affect the flow. Three models are used that vary the strength of the channel topography S = rootf Delta hD/Uh, where f is the Coriolis parameter, Deltah is the difference between the shelf dept h and the channel depth, D is the width of the slope into the channel, U is the maximum speed of the jet at the inflow, and h is the depth of the shel f. Estimation of the path of the jet from the inflow parameters and the geo metry of the channel is possible in some cases. Generally, for large S the Row follows the topography of the channel and for small S the flow crosses the channel. The motivation for this study is the episodic flow of Scotian Shelf water from the Scotian Shelf across the Northeast Channel to Georges Bank. The steady, inviscid, non-linear, barotropic dynamics studied here do not allow such a flow for a channel of similar dimensions to the Northeast Channel and for flow speeds within the oceanographic range. Other factors such as stratification, wind stress and time variability need to be introdu ced to account for this phenomenon. (C) 2000 Elsevier Science Ltd. All righ ts reserved.