Observed Bottom Intensified Diurnal Currents on the Upper Continental Slope North of Svalbard

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Abstract In the Arctic Ocean, dissipation is generally weak except for some hot spots on the continental slope or along the edge of the Yermak Plateau where observations suggest that tidal currents are the main source of dissipation. In this study, we analyze observations collected between September 2017 and November 2019 from a mooring deployed on the sea floor at a depth of 500 m on the upper slope north of Svalbard, as part of the INTAROS project. Thanks to a 2‐year long time series of current and hydrographic properties, we report periods of amplification of the cross‐slope bottom velocity at the diurnal frequency. The amplification occurs mainly in late fall‐early winter and in summer and can be accompanied by diurnal variations of the temperature and salinity, while the diurnal signal vanishes in late winter‐early spring. Experiments with Brink’s (2006, https://github.com/KenCTW/BaroclWaves ) simplified model suggest that the observed ambient stratification and the bottom topography of the region together create favorable conditions for the resonance of coastal trapped waves generated by the diurnal tides. However, such conditions are not present throughout the year; the combined effects of weakened stratification and strong mean along‐slope current in late winter prevent the occurrence of such a resonance. The stratification between 250 and 500 m appears instrumental to bottom intensification of the cross‐slope current during specific periods. However, it was not possible to identify signatures of enhanced dissipation associated with such bottom‐intensified diurnal currents.

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