Evidence of diurnal shelf waves in satellite-tracked drifter trajectories off the Kuril Islands

Satellite-tracked surface drifters deployed in September 1993 in the vicini ty of the Kuril-Kamchatka Trench were advected onto the Pacific continental shelf of the Kuril Islands where they encountered strong (40-50 cm s(-1)) diurnal tidal currents. One of the drifters subsequently passed through Fri z Strait into the Sea of Okhotsk. experiencing intense (>100 cm s(-1)) diur nal currents in the strait and strong (35-40 cm s(-1)) diurnal currents ove r the Okhotsk shelf of the Kuril Islands. The across-shelf structure of the diurnal tidal currents is shown to be consistent with that of free. topogr aphically trapped subinertial waves propagating along the continental margi n of the islands. Of the three continental shelf wave models considered (a barotropic model with zero mean flow, a barotropic model with nonzero along shore mean flow, and a baroclinic model based on the observed density struc ture), only the baroclinic model accurately explains the main features of t he diurnal currents for the Pacific and Okhotsk shelves. Both first and sec ond mode waves contribute to the diurnal currents.