First Evidence of Coherent Bands of Strong Turbulent Layers Associated with High-Wavenumber Internal-Wave Shear in the Upstream Kuroshio
| Autor: | Takahiro Tanaka, Ryuichiro Inoue, Hirohiko Nakamura, Toru Yamashiro, Eisuke Tsutsumi, Daisuke Hasegawa, Takeyoshi Nagai |
|---|---|
| Rok vydání: | 2017 |
| Předmět: |
geography
Multidisciplinary geography.geographical_feature_category 010504 meteorology & atmospheric sciences 010505 oceanography Turbulence Continental shelf Internal tide lcsh:R lcsh:Medicine Geophysics Internal wave 01 natural sciences Article Eddy diffusion Physics::Fluid Dynamics Turbulence kinetic energy Physics::Space Physics Wavenumber lcsh:Q lcsh:Science Thermocline Geology 0105 earth and related environmental sciences |
| Zdroj: | Scientific Reports, Vol 7, Iss 1, Pp 1-14 (2017) Scientific Reports |
| ISSN: | 2045-2322 |
| Popis: | The upstream Kuroshio flows through Okinawa Trough and the Tokara island chain, the region near the continental shelf of the East China Sea and shallow seamounts, where the Kuroshio can induce strong mixing over the shallow topography. Also, tidal currents over the rough topography may produce internal tides, and associated turbulence. The previous observations show energetic high vertical wavenumber near-inertial wave shear in the Kuroshio thermocline, which implies strong turbulent mixing. However, direct turbulence measurements in this region are very scarce. Using high lateral resolution (1–2 km) direct turbulence measurements, we show here, for the first time, that strong turbulent layers form spatially coherent banded structures with lateral scales of >O(10 km), associated with bands of near-inertial wave/diurnal internal tide shear of high vertical wavenumber in the upstream Kuroshio. The turbulent kinetic energy dissipation rates within these turbulent layers are >O(10−7 W kg−1), and estimated vertical eddy diffusivity shows >O(10−4 m2 s−1) on average. These results suggest that the high vertical wavenumber near-inertial waves propagating in the upstream Kuroshio could have large impacts on the watermass modifications, momentum mixing, nutrient supply, and associated biogeochemical responses in its downstream. |
| Databáze: | OpenAIRE |
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