Tidally Generated Internal Waves in the Vilkitsky Strait, Arctic Ocean

Abstract In this study, we describe in situ measurements of internal waves (IWs) in the Vilkitsky Strait, which connects the Kara and Laptev Seas in the Arctic Ocean. The measurements were conducted at three moorings over three weeks in autumn 2019 and demonstrated the presence of highly intense IWs. Although the study region is located poleward of the M 2 critical latitude (74.5°N) for linear IWs, the measurements revealed the presence of semidiurnal ITWs with periods near 12.4 hr. The vertical displacements of isotherms caused by semidiurnal internal tides reached 10–17 m. In the coastal zone, the shape of ITWs differs significantly from a sinusoidal form due to pronounced nonlinear effects at shallow depths. Field observations clearly show the generation of high‐frequency IWs during the propagation of internal tides, as confirmed by the spectral analysis of temperature and isotherm displacement data. Joint analysis of in situ and synthetic aperture radar satellite observations reveals the regular occurrence of intense nonlinear high‐frequency IWs with phase velocities of 0.5–1.5 m/s, ranked wavelengths of 100–600 m, periods of 5–120 min, and amplitudes of 4–20 m. The predominant propagation direction of nonlinear IWs is along the strait aligned with the tidal currents. However, satellite data also indicate the occurrence of cross‐strait propagating IWs, potentially implying various source regions and mechanisms of their generation in the strait. Additionally, an episode of the second mode IWs was identified.