Publication Date:
2023-07-11
Description:
Recent theoretical studies〈sup〉 〈/sup〉have hypothesized that deep-ocean upwelling may be primarily sustained by mixing processes within a thin bottom boundary layer (BBL) adjacent to the seafloor. However, this proposition appears at odds with several decades of observations of ocean turbulence, which suggest a pervasive intensification of mixing with depth conducive to deep-ocean downwelling. Here, we reconcile such intensification with the newly-proposed paradigm of BBL-focussed upwelling in the context of a typical continental-slope canyon, in which very rapid upwelling is observed. We show that upwelling along the canyon stems from episodic cells of convective turbulent mixing up to 250 m in height, generated by tidal currents sweeping up- and down-canyon. As drag against the seabed decelerates the currents’ base, their upper layers convey dense waters over slower-flowing lighter waters below, causing the dense waters to convectively mix, lighten and upwell. We discuss how this upwelling mechanism is likely to be of wider representativeness, lending support to the view that deep-ocean upwelling may predominantly occur along the ocean’s sloping boundaries.
Language:
English
Type:
info:eu-repo/semantics/conferenceObject
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