A Strong Internal Solitary Wave with Extreme Velocity Captured Northeast of Dong-Sha Atoll in the Northern South China Sea

Abstract

Internal solitary waves (ISWs) in the South China Sea (SCS) have received considerable attention. This paper reports on a strong ISW captured northeast of Dong-Sha Atoll on 22 May 2011 by shipboard Acoustic Doppler Current Profiler (ADCP), which had the largest velocity among the ISWs so far reported in the global ocean. The peak westward velocity (u) was 2.94 m/s, and the peak downward velocity (w) was 0.63 m/s, indicating a first baroclinic mode depression wave. The amplitude of ISW inferred from ADCP backscatter was about 97 m. 2.2 h later, a trailing wave was captured with a peak westward velocity and downward velocity of 2.24 m/s and 0.42 m/s, respectively, surprisingly large for a trailing wave, suggesting that the ISW is type-A wave. The estimated baroclinic current induced by the leading ISW was much larger than the barotropic current. The Korteweg-De Vries (KdV) theoretical phase speed and the phase speed inferred from the satellite images were 1.76 m/s and 1.59 m/s, respectively. The peak horizontal velocity exceeded the phase speed, suggesting the ISW was close to or already in the process of breaking and may have formed a trapped core.

A Preliminary Study of Suspended Matters Variation Associated with Hypoxia and Shoaling Internal Tides on the Continental Shelf of the Northern Andaman Sea

“…At the same time, the temperature at a depth of 113 m increased sharply by 0.9 • C (Figure 3b), indicating downward movement of warm water in the upper layer. Both the distribution of the MVBS and temperature had a spike-like pattern, in accordance with the characteristics of internal solitary waves [51]. In terms of vertical transport depth, internal solitary waves exhibit greater strength compared to internal tides.…”

“…In linear internal tides, horizontal velocities are typically an order of magnitude larger than vertical velocities. However, during the nonlinear evolution of internal tides, vertical velocities can significantly increase, reaching magnitudes comparable to horizontal velocities [51]. Therefore, the first mode in the EOF primarily reflected the vertical velocities excited during the nonlinear evolution of internal tides.…”

Water Exchange Due to Wind and Waves in a Monsoon Prevailing Tropical Atoll

“…In this study, I use Dongsha Atoll as an example to study the tide-, wind-, and wavedriven exchange processes between the lagoon and the open ocean. Many studies about Dongsha Atoll have focused on topics of internal waves and their implications ( [19][20][21][22][23][24]); however, to my best knowledge, there is no model study about the circulations inside the Dongsha Atoll. A current-wave coupled model, COAWST, which is widely used in studies about current-wave interactions in several regions (e.g., [25][26][27]; see Section 2.2 for details of the model) with realistic atoll bathymetry, atmospheric, and oceanic conditions, was built, and numerical experiments were conducted to investigate the processes of water exchange in the Dongsha Atoll.…”

Noise of Internal Solitary Waves Measured by Mooring-Mounted Hydrophone Array in the South China Sea

“…As such, recent years have seen growing attention paid to ISWs in the South China Sea. Xu and Chen reported a strong ISW in the northeast of Dong-sha Atoll, which had a velocity of 2.94 m/s, the largest among the ISWs in global oceans [9]. Cai et al summarized the generation and evolution of ISWs in the South China Sea [10].…”