A snapshot of turbulence in the Northeastern Magellan Strait
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Date
2024
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Abstract
First-ever measurements of the turbulent kinetic energy (TKE) dissipation rate in the northeastern Strait of Magellan (Seg-unda Angostura region) taken in March 2019 are reported here. At the time of microstructure measurements, the magnitude of the reversing tidal current ranged between 0.8 and 1.2 ms(-1). The probability distribution of the TKE dissipation rate in the water interior above the bottom boundary layer was lognormal with a high median value epsilon(MS)(med) = 1.2x10(-6) Wkg(-1). Strong vertical shear, (1-2)x10(-2) s(-1), in the weakly stratified water interior ensued a sub-critical gradient Richardson number Ri < 10(-1) - 10(-2). In the bottom boundary layer (BBL), the vertical shear and the TKE dissipation rate both decreased exponentially with the distance from the seafloor xi, leading to a turbulent regime with an eddy viscosity K-M similar to 10(-3) m(2)/s, which varied with time and location, while being independent of the vertical coordinate in the upper part of BBL (for xi > similar to 2 meters above the bottom).
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Keywords
Strait of Magellan, Segunda Angostura, Tidal Currents, Turbulence, BBL