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- Title
Seasonal West‐East Seesaw of M<sub>2</sub> Internal Tides From the Luzon Strait.
- Authors
Zhao, Zhongxiang; Qiu, Bo
- Abstract
Satellite altimetry sea surface height (SSH) measurements from 1993 to 2017 are used to investigate the seasonal variability of mode‐1 M2 internal tides from the Luzon Strait. The 25 years of SSH data are divided into four seasonal subsets, from which four seasonal internal tide models are constructed following the same mapping procedure. Climatological seasonal hydrography in the World Ocean Atlas 2013 is used to calculate two seasonally variable parameters required in the mapping procedure: Wavelength and the transfer function from the SSH amplitude to depth‐integrated energy flux. The M2 internal tides from the Luzon Strait are extracted using propagation direction determined in plane wave analysis. The satellite results show that the westward and eastward M2 internal tides both demonstrate significant seasonal variation. The westward and eastward internal tides seesaw seasonally: The westward internal tides strengthen (weaken) in summer and fall (winter and spring); while the eastward internal tides strengthen (weaken) in winter and spring (summer and fall). We suggest that the seasonal seesaw is mainly determined by ocean stratification and the Kuroshio Current; however, further studies are needed to quantify their relative contributions. Plain Language Summary: The generation, propagation, and dissipation of internal tides are affected by a variety of ocean dynamic processes, such that internal tides are subject to temporal variation over timescales from days to decades. A knowledge of their temporal variation is key to advance our understanding of their lifecycle in various ocean environments, their contribution to ocean mixing, and their response to global ocean warming. Two fundamental questions are still poorly understood: How internal tides vary over various timescales? What are the driving mechanisms? Satellite altimetry offers a unique tool for observing internal tides on a global scale from space. Internal tides in different propagation directions in a complex multi‐wave field can be separated by plane wave analysis. This paper reveals that M2 internal tides from the Luzon Strait demonstrate significant seasonal variation and that they are likely modulated by ocean stratification and the Kuroshio Current. This work paves a path to address the above two fundamental scientific questions. Key Points: Seasonal mode‐1 M2 internal tides from the Luzon Strait are observed using seasonally subsetted satellite altimetry data from 1993 to 2017Westward and eastward M2 internal tides from the Luzon Strait both demonstrate significant seasonal variationThe westward internal tides strengthen (weaken) in summer and fall (winter and spring); the opposite is true for the eastward internal tides
- Subjects
SEASONS; SPRING; OCEANIC mixing; STRAITS; HYDROGRAPHY; WAVE analysis
- Publication
Journal of Geophysical Research. Oceans, 2023, Vol 128, Issue 3, p1
- ISSN
2169-9275
- Publication type
Article
- DOI
10.1029/2022JC019281