SEDIMENT RESUSPENSION AND MIXING BY RESONANTLY GENERATED INTERNAL SOLITARY WAVES

The observation of internal solitary waves (ISWs) propagating upstream along a strongly stratified bottom layer on the California shelf is r eported. An increased concentration of particulates in the water colum n accompanies the passage of these ISW packets. The estimated local Ri chardson number in the bottom vicinity is around 1/4, and a vertical c oefficient of eddy diffusivity of order 10(-2) m(2) s(-1) is associate d with the upstream propagating leading ISW. The leading ISW gave rise to reversed flow in an 8-m layer above the bottom. It is argued that the upstream propagating ISWs were generated by resonant flow over bot tom topography. Internal waves generated in this way seem to be freque nt in the record of a month-long experiment. Model results suggest tha t the ISWs can carry up to 73% of such generated long wave energy. The ocean conditions at the site are similar to those of other coastal si tes, which suggests that the phenomenon described here may be common.