Partition of energy Loss from the Barotropic Tide in Fjords

Abstract

As the barotropic tide propagates into and out of a fjord, it loses energy to friction, internal tides and high-frequency internal waves. Estimates of these losses for three British Columbia fjords, using current meter data, indicate that friction is negligible in two, but important in one inlet. The length and depth of the sill determines the importance of friction. When friction is not important, most of the energy lost goes into the internal tide but less than half of this energy propagates away from the sill. Simple models of the internal tide predict the correct energy transfer to satisfy an energy budget but do not agree with observations of the internal tidal energy flux away from the sill. Energy loss from the internal tide in or near the generation zone would account for the discrepancy. The energy flux of the high-frequency internal wave field is relatively small, about 2% of the energy lost.