The effect of river discharge on the residual circulation in the Eastern Irish Sea

Abstract

A method is described for measuring horizontal density gradients using data from a current meter mooring which permits the density driven component to be isolated from the observed residual currents. An estuarine-like residual circulation, towards the coast near the bottom and to the right of the offshore direction near the surface, is a result of the river discharge induced horizontal density gradients near the centre of the Eastern Irish Sea. This indicates an intermediate situation between an estuary where friction is large and the open sea where the geostrophic effect is dominant. The above method may provide more appropriate values against which to compare theoretical and numerical models of the density driven residual circulation than the charts used up to now. In these charts, the density driven component is inextricably intermingled with the effects of other driving forces. The adjustment of complex numerical models that take account of several driving forces could also be considerably simplified.