APPLICATION OF A TRANSIENT REDUCED GRAVITY PLUME MODEL TO THE DENMARKSTRAIT OVERFLOW

A hydrostatic, reduced gravity, two-dimensional primitive equation num erical model for the simulation of transient bottom arrested gravity p lumes was developed by adopting an algorithm from a wadden sea model ( a model that simulates the wetting and drying of mud flats, sand banks , etc.) with a movable lateral boundary. The vertically integrated non linear rotational model accounts for the dissipation of momentum due t o bottom friction and for the entrainment of water mass proper-ties fr om a spatially structured but stagnant ambient water body. It predicts the temporal and spatial evolution of the flow field and the water ma ss modification within a gravity plume that descends on an arbitrary t opography. Previous model investigations considered a laterally integr ated streamtube, whereas our model resolves the plume horizontally. In the streamtube approach it was assumed that the plume descends in a s tationary, almost geostrophic balance modified only by bottom drag and entrainment. The results of this model demonstrate that this balance may be disturbed whenever the plume encounters topographic disturbance s, which, for the initial intruding phase in particular, accounts for its highly translent character. The model results are in good agreemen t with theoretical and laboratory investigations and with observations , as is demonstrated by some basic test experiments. An application to the overflow of dense water through the Denmark Strait is presented.