On the Structure of Transient Upwelling Events

Abstract

Abstract Nearshore transcends, following the development of transient coastal upwelling, characteristically show “intermediate” density fluid occupying the immediate nearshore band. Large cross-shore particle excursions during the development of upwelling may be inferred from be-fore and after transects, and the movement of surface layers seaward, intermediate density fluid shoreward through a distance of the order of kilometers, and the bottom layers also shoreward by a 1esser amount. Some inevitable vertical Mixing together with the large cross-shore displacements results in efficient cross-shore mass exchange. The main dynamical features of similar events may be investigated by means of three-layer models. Linear theory is conveniently discussed first, the conclusions of which are easily generalized to multilayer models, Finite-amplitude (i.e., “full”) upwelling is then considered using a potential-vorticity conserving impulsive model. The results show that the wind “peels” off the surface layer over w...