Observations of high-frequency internal wave near submesoscale fronts

This study focuses on the phenomena of internal wave generation associated with submesoscale frontal features, which may be significant for energy transfers in the upper ocean. A marine X-band radar observed a series of organized bands, with an interval of ~150 m, near a submesoscale front (SF) in the northern Gulf of Mexico. The bands were observed, via continuous 1-minute averaged radar intensity images, to propagate towards the SF at 0.30 m/s. The celerity and spacing of the bands is consistent with the surface expression of high-frequency internal waves (HIW) and the conditions under which they were observed exclude the possibility that they were signatures of Langmuir circulation cells or atmospheric rolls. A second order KdV model based on the environmental parameters, agrees with the observed HIW speed. In addition, vertical profiles of potential vorticity indicate that the dynamic conditions near the front were conducive to inertial and symmetric instabilities.