| Autor: |
Cheng, Yu‐Hsin1 (AUTHOR) yhcheng@email.ntou.edu.tw, Chang, Ming‐Huei2 (AUTHOR), Yang, Yiing Jang2 (AUTHOR), Jan, Sen2 (AUTHOR), Ramp, Steven R.3 (AUTHOR), Davis, Kristen A.4 (AUTHOR), Reeder, D. Benjamin5 (AUTHOR) |
| Předmět: |
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| Zdroj: |
Journal of Geophysical Research. Oceans. Aug2024, Vol. 129 Issue 8, p1-18. 18p. |
| Abstrakt: |
Understanding of internal solitary wave (ISW) behavior has been limited due to sparse observations. We used high‐resolution Himawari‐8 satellite imagery and mooring observations to reveal the two‐dimensional (x–y) propagation process of ISWs in the South China Sea as they westward propagate onto the Dongsha plateau and encounter Dongsha Atoll. The 2D depiction of wave speed distribution, derived from detected wave crest positions every 10 min, shows the wave speeds range from 3 m s−1 to 1 m s−1 and have a tight correspondence to the local water depth. The correlation coefficient between the wave speeds and the Dubreil–Jacotin–Long (DJL) solutions is around 0.7, with a root mean squared value of 0.26 m s−1, and the representative available potential energy for this region is considered to be 130 MJ m−1. However, diffusions of wave speed in the ISW's lateral direction, particularly around abrupt topography, contribute to occurrences of outliers. Pairs of incident and reflected waves are well recognized east of Dongsha Atoll. The incident wave packet is known to be classified into a‐type and b‐type waves. The reflected waves associated with the b‐wave, identifiable as mode‐1 depression ISWs, are traced back to their generation site at depths of 100–200 m. In contrast, the reflected waves of the a‐wave remain elusive in shallower waters (<300 m), likely due to interference from their longer incident counterparts. The reflected wave, however, is slower and decelerates toward deeper water, deviating from the DJL prediction. These comprehensive observations can help refine models for improved accuracy. Plain Language Summary: Internal solitary waves (ISWs) in the South China Sea that propagate westward onto the Dongsha plateau and encounter Dongsha Atoll are traced. Wave speed varies from 3 m s−1 to 1 m s−1 and corresponds well to the local water depth. The variation of wave speed with depth shows an agreement with the solutions of a standard model (0.7 correlation coefficient), except in regions around abrupt topography. As the wave passes over a seamount, discrepancies in wave speed across the wave's lateral direction can contribute to occurrences of outliers. The incident wave and its reflected counterpart are well recognized semidiurnally to the east of Dongsha Atoll. However, when overlapping with the prior incident wave group, the reflected waves are unclear and difficult to distinguish. The reflected waves can be identified as waves causing isotherms to dip downward and creating a trough‐like depression in the water column. Their propagation speed is generally slower than its incident counterpart. The horizontal 2D depiction of wave speed distribution revisits the process from westward propagating ISWs to their reflected counterpart and improves understanding of reflected waves. Key Points: The spatial evolution of wave speeds with high spatiotemporal resolution mostly agrees with the Dubreil–Jacotin–Long modelAround abrupt topography, the wave's horizontal 2D distribution reveals the lateral diffusion of wave speeds along the wave crestInternal solitary waves propagating westward are observed to reflect off topography around the Dongsha Plateau by both satellite and mooring [ABSTRACT FROM AUTHOR] |
| Databáze: |
GreenFILE |
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