Evidence of enhanced turbulent dissipation in the frontogenetic Kuroshio Front thermocline

Takeyoshi Nagai; Amit Tandon; Hidekatsu Yamazaki; Mark J Doubell

doi:10.1029/2009GL038832

Evidence of enhanced turbulent dissipation in the frontogenetic Kuroshio Front thermocline

Takeyoshi Nagai, Amit Tandon, Hidekatsu Yamazaki, Mark J Doubell

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Abstract

Enhanced turbulent dissipation, O(10^-8- 10^-7) Wkg^-1 in the thermocline on the cyclonic side of the Kuroshio Front was observed during a period of frontogenesis, using a microstructure profiler, XBT and ADCP along 143°E across the Kuroshio Front in August 2008. The eddy diffusivity corresponding to the mixing below the central jet is estimated to be O(10^-4-10^-3) m² s^-1. The strong turbulent mixing we observed in the Kuroshio is in sharp contrast to previous field measurements which found that small scale diapycnal mixing in western boundary currents remains at levels typically measured in the open ocean thermocline. The turbulence in the Kuroshio is attributed to frontogenesis arising out of an estimated confluence rate of O(10^-5 ) s ^-1 based on satellite altimeters, suggesting the ubiquity of a forward energy cascade from mesoscale to microscale turbulence near ocean fronts as indicated by recent theoretical studies.

Original language	English
Article number	L12609
Number of pages	6
Journal	Geophysical Research Letters
Volume	36
Issue number	12
DOIs	https://doi.org/10.1029/2009GL038832
Publication status	Published - Jun 2009
Externally published	Yes

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title = "Evidence of enhanced turbulent dissipation in the frontogenetic Kuroshio Front thermocline",

abstract = "Enhanced turbulent dissipation, O(10-8- 10-7) Wkg-1 in the thermocline on the cyclonic side of the Kuroshio Front was observed during a period of frontogenesis, using a microstructure profiler, XBT and ADCP along 143°E across the Kuroshio Front in August 2008. The eddy diffusivity corresponding to the mixing below the central jet is estimated to be O(10-4-10-3) m2 s-1. The strong turbulent mixing we observed in the Kuroshio is in sharp contrast to previous field measurements which found that small scale diapycnal mixing in western boundary currents remains at levels typically measured in the open ocean thermocline. The turbulence in the Kuroshio is attributed to frontogenesis arising out of an estimated confluence rate of O(10-5 ) s -1 based on satellite altimeters, suggesting the ubiquity of a forward energy cascade from mesoscale to microscale turbulence near ocean fronts as indicated by recent theoretical studies.",

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AU - Nagai, Takeyoshi

AU - Tandon, Amit

AU - Yamazaki, Hidekatsu

AU - Doubell, Mark J

PY - 2009/6

Y1 - 2009/6

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AB - Enhanced turbulent dissipation, O(10-8- 10-7) Wkg-1 in the thermocline on the cyclonic side of the Kuroshio Front was observed during a period of frontogenesis, using a microstructure profiler, XBT and ADCP along 143°E across the Kuroshio Front in August 2008. The eddy diffusivity corresponding to the mixing below the central jet is estimated to be O(10-4-10-3) m2 s-1. The strong turbulent mixing we observed in the Kuroshio is in sharp contrast to previous field measurements which found that small scale diapycnal mixing in western boundary currents remains at levels typically measured in the open ocean thermocline. The turbulence in the Kuroshio is attributed to frontogenesis arising out of an estimated confluence rate of O(10-5 ) s -1 based on satellite altimeters, suggesting the ubiquity of a forward energy cascade from mesoscale to microscale turbulence near ocean fronts as indicated by recent theoretical studies.

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Evidence of enhanced turbulent dissipation in the frontogenetic Kuroshio Front thermocline

Abstract

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