Transverse structure of turbulence in a rotating gravity current

Abstract

Synoptic, high‐resolution, measurements of turbulent kinetic energy dissipation, current velocity and water column stratification across a fast (up to 0.7 m s −1 ) oceanic saline gravity current are presented. Our data provide, for the first time, a detailed two‐dimensional picture of the turbulence structure inside a gravity current. Strong boundary‐layer and interfacial turbulence can be distinguished from a quiet core, and a strong asymmetry of mixing near the outer edges of the gravity current is apparent. This asymmetry is mirrored by the computed entrainment velocities, varying approximately by a factor of 5 across the gravity current. It is argued that the asymmetry is due to rotational effects that can be clearly identified also in the velocity and density fields.