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- Title
The potential role of thermohaline–shear instability in turbulence production in the Bering Sea and the subarctic North Pacific.
- Authors
Tanaka, Mamoru; Yoshida, Jiro; Lee, Keunjong; Goto, Yasutaka; Tanaka, Takahiro; Ueno, Hiromichi; Onishi, Hiroji; Yasuda, Ichiro
- Abstract
A recent linear stability analysis and a numerical simulation suggest that diffusive convection (DC), a regime of the double-diffusive convection, plays a potential role in onset of thermohaline–shear instability, implying that DC could contribute to turbulence production in the oceans. However, an existence of such a thermohaline–shear instability has not been examined in real oceans. We examine if this newly proposed instability mechanism exists in the subarctic North Pacific by analyzing our fine- and micro-scale turbulence measurement data. Vertical inversions were cautiously detected in seawater density profiles and used as a proxy for instability events for gradient Richardson number larger than the critical value of 1/4. We found that a portion of inversions were associated with active DC. Such DC-related inversions exhibited elevated levels of turbulent kinetic energy dissipation rate even for gradient Richardson number largely exceeding 1/4. Our estimate suggested that the thermohaline–shear instability contributes to roughly only 10% of the dissipation of turbulent kinetic energy in the diffusively convective layer in our observation site.
- Subjects
RICHARDSON number; TURBULENCE; ENERGY dissipation; KINETIC energy; OCEAN turbulence
- Publication
Journal of Oceanography, 2021, Vol 77, Issue 3, p431
- ISSN
0916-8370
- Publication type
Article
- DOI
10.1007/s10872-021-00602-9