Propagation and dissipation of tidal internal waves in the North Pacific on the basis of the MEGAPOLYGON data, an experiment with 170 moored buoys

In 1987 the Shirshov Institute of Oceanology conducted a large scale experiment “MEGAPOLYGON” in the North Pacific, north of the Kuroshio. A cluster of 177 moored buoys was set for two months in the region between 38°-42° N and 152°-158° E. The moorings were set at a distance of 24 miles. The current meters were set at 120 m and 1200 m levels. The time sampling was 30 minutes. The period of the measurements in August September, 1987 is characterized by the influence of powerful meteorological typhoons which strongly affected the surface floats of the moorings. This led to the displacement and drift of several moorings and to the failure of the records in the instruments. This region is also an area of intensive fishery, and unfortunately some of the moorings were entangled in the fishing nets, which caused displacement and losses of the moorings. The main objective of the experiment was to study synoptic and mesoscale eddies and rings of the Kuroshio. At the same time, the cluster provides good opportunities to study tidal internal waves with a spatial scale of the order of hundred kilometers. The spatial location of moorings with current meters in the cluster forms a good antenna to study tidal internal waves and their variability. The main source for the generation of tidal internal waves in the North Pacific is the Emperor Ridge. Tidal internal waves are generated due to the interaction of the barotropic tide with the bottom topography over the slopes of the ridge d