Thermal Fronts Generated by Internal Waves Propagating Obliquely along the Continental Slope

Abstract

Rapid temperature falls occurring at semidiurnal periods are observed close to the bottom above the continental slope in the Bay of Biscay. Simultaneous current measurements reveal that the abrupt temperature decrease O(0.5 K) within one minute is associated with a brief downslope current, contrary to previous observations. It is suggested that the flow field associated with internal waves propagating obliquely downslope is responsible for advecting denser water higher on the slope than lighter fluid, resulting in a gravitationally unstable stratification. The collapse of this stratification is observed as a thermal front passing the moored instruments.