Zimin A. V., Svergun E. I.
This paper discusses the results of observations of the height of short-period internal waves conducted in summer seasons of the years 2010—2017. The work was carried out in the Western Solovetskaya Salma, on the border of the Basin and the Gorlo Strait, in the Bay of Dvina in the White Sea; near Harlow Island, the island of Harlov, near Cape Teribersky in the Barents Sea; near Cape Svobodny, above the shelf break near the Kuril Basin in the Okhotsk Sea. The duration of measurements in each area varied from 25 to 80 hours. It is established that waves’ heights have everywhere the highest repeatability 1—3 meters. Intensive internal waves (higher than 10 meters) are regularly observed in the areas of Western Solovetskaya Salma in the White Sea and near cape Svobodny in the Okhotsk Sea. Estimates of the probability of occurrence of extreme internal waves, which can be observed once a month during the warm season, are made in the assumption of the steady-state of wave-forming factors. It is established that intensive internal waves can be observed in all seas, and in the White and the Okhotsk Seas the heights of extreme waves can exceed 15 meters once a month. For areas where waves with extreme heights were recorded, the calculation of the bottom flow velocity and variations of bottom pressure were made. It is found that the variations of bottom pressure caused by extreme internal waves varies from 120 to 380 Pa, and flow velocities induced by waves vary from 7 to 17 cm/s. Accordingly, variations of the bottom pressure will not have a significant impact on offshore structures, and flow associated with extreme internal waves are able to erode silt and sand soils. However, working together with tidal flows, such flows can contribute to significant transport of sediment, which can have an impact on the stability of underwater hydraulic structures.