Observational Evidence of Surface Wave‐Generated Strong Ocean Turbulence. Issue 2 (27th January 2020)

• Record Type: Journal Article
• Authors: Ma, Hongyu; Dai, Dejun; Guo, Jingsong; Qiao, Fangli
• Is Part Of: Journal of geophysical research. Volume 125:Issue 2(2020)
• Page Start: n/a
• Page End: n/a
• Publication Date: 2020-01-27
• Subjects: Oceanography -- Periodicals; 551.4605
• DOI: 10.1029/2019JC015657
• Languages: English
• ISSNs: 2169-9275

Abstract

Abstract: By using an acoustic Doppler velocimeter mounted on the seabed of the continental shelf of the northern South China Sea, high frequency velocity fluctuations were measured for 4.5 days. The turbulent kinetic energy dissipation rate was estimated. During the observation, the strong ocean response to Typhoon Rammasun was recorded to compare the turbulent characteristics before and during the typhoon. The results show that the turbulence near the seabed is mainly generated by the tidal current shear and exhibits a quarter diurnal variation during the period before the typhoon. During the typhoon period, the dissipation rate ε dramatically increased from 1 × 10 −6 to 1 × 10 −2 m 2 s −3 within a short time, and the significant wave height and the surface wave orbital velocity showed the same tendency. This finding suggests that the turbulence is dominantly generated by the surface waves near the seabed. Plain Language Summary: Under typhoon conditions, the turbulence characteristic at the bottom boundary layer of the continental shelf is not clear. Therefore, the field observation was carried out, and the results show that the turbulence kinetic energy dissipation rate increases 4 orders under Typhoon Rammasun. This strong turbulence is dominantly generated by the surface waves near the seabed. Understanding the turbulence characteristics is important for studying turbulent mixing, turbulence parameterization, pollutant dispersion, sediment dynamics, and biological activities. Key Points: The strong turbulence was measured with ADV on the continental shelf of the northern South China Sea during Typhoon Rammasun in 2014 The turbulent kinetic energy dissipation rate increases 4 orders of magnitude under typhoon condition Sea surface waves play a key role in the generation of strong turbulence in the wave bottom boundary layer