Distinct Variability between Semidiurnal and Diurnal Internal Tides at the East China Sea Shelf
Breaking internal tides and induced mixing are critical to shelf dynamics, including heat and mass exchanges. Spatiotemporal variability of internal tides and modulation factors for the southern East China Sea shelf were examined based on a combination of a three-month mooring velocity and satellite...
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| Format: | Article |
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MDPI AG
2022-05-01
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| Series: | Remote Sensing |
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| Online Access: | https://www.mdpi.com/2072-4292/14/11/2570 |
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| author | Weidong Wang Robin Robertson Yang Wang Chen Zhao Zhanjiu Hao Baoshu Yin Zhenhua Xu |
| author_facet | Weidong Wang Robin Robertson Yang Wang Chen Zhao Zhanjiu Hao Baoshu Yin Zhenhua Xu |
| author_sort | Weidong Wang |
| collection | DOAJ |
| description | Breaking internal tides and induced mixing are critical to shelf dynamics, including heat and mass exchanges. Spatiotemporal variability of internal tides and modulation factors for the southern East China Sea shelf were examined based on a combination of a three-month mooring velocity and satellite altimeter data. Semidiurnal and diurnal internal tides exhibited distinct temporal trends, with the semidiurnal internal tides enhanced by an order of magnitude during the latter half of the record, while the diurnal internal tides followed quasi spring-neap cycles with a generally stable intensity except for two specific periods of strengthening. These internal tides probably originated remotely over the shelf-slope area northeast of Taiwan. Time-varying stratification was the most important factor for the internal tidal magnitude. In addition, varying background currents influenced the diurnal critical latitude band, which explains the slightly enhanced diurnal internal tides during the two periods. Although both semidiurnal and diurnal internal tides were mode-1 dominated, the semidiurnal internal tides were surface intensified while the diurnal tides were bottom intensified. The proportion of higher mode internal tides increased during robust eddy activities. Stronger background vertical shear corresponded to high-frequency events and energy transfers from tidal frequencies to high frequencies associated with turbulent mixing. |
| first_indexed | 2024-03-10T00:55:42Z |
| format | Article |
| id | doaj.art-55f64b202a31466bb4fce3afff218798 |
| institution | Directory Open Access Journal |
| issn | 2072-4292 |
| language | English |
| last_indexed | 2024-03-10T00:55:42Z |
| publishDate | 2022-05-01 |
| publisher | MDPI AG |
| record_format | Article |
| series | Remote Sensing |
| spelling | doaj.art-55f64b202a31466bb4fce3afff2187982023-11-23T14:43:51ZengMDPI AGRemote Sensing2072-42922022-05-011411257010.3390/rs14112570Distinct Variability between Semidiurnal and Diurnal Internal Tides at the East China Sea ShelfWeidong Wang0Robin Robertson1Yang Wang2Chen Zhao3Zhanjiu Hao4Baoshu Yin5Zhenhua Xu6CAS Key Laboratory of Ocean Circulation and Waves, Institute of Oceanology, Chinese Academy of Sciences, Qingdao 266071, ChinaChina-Asean College of Marine Science, Xiamen University Malaysia, Sepang 43900, MalaysiaCAS Key Laboratory of Ocean Circulation and Waves, Institute of Oceanology, Chinese Academy of Sciences, Qingdao 266071, ChinaCAS Key Laboratory of Ocean Circulation and Waves, Institute of Oceanology, Chinese Academy of Sciences, Qingdao 266071, ChinaCAS Key Laboratory of Ocean Circulation and Waves, Institute of Oceanology, Chinese Academy of Sciences, Qingdao 266071, ChinaCAS Key Laboratory of Ocean Circulation and Waves, Institute of Oceanology, Chinese Academy of Sciences, Qingdao 266071, ChinaCAS Key Laboratory of Ocean Circulation and Waves, Institute of Oceanology, Chinese Academy of Sciences, Qingdao 266071, ChinaBreaking internal tides and induced mixing are critical to shelf dynamics, including heat and mass exchanges. Spatiotemporal variability of internal tides and modulation factors for the southern East China Sea shelf were examined based on a combination of a three-month mooring velocity and satellite altimeter data. Semidiurnal and diurnal internal tides exhibited distinct temporal trends, with the semidiurnal internal tides enhanced by an order of magnitude during the latter half of the record, while the diurnal internal tides followed quasi spring-neap cycles with a generally stable intensity except for two specific periods of strengthening. These internal tides probably originated remotely over the shelf-slope area northeast of Taiwan. Time-varying stratification was the most important factor for the internal tidal magnitude. In addition, varying background currents influenced the diurnal critical latitude band, which explains the slightly enhanced diurnal internal tides during the two periods. Although both semidiurnal and diurnal internal tides were mode-1 dominated, the semidiurnal internal tides were surface intensified while the diurnal tides were bottom intensified. The proportion of higher mode internal tides increased during robust eddy activities. Stronger background vertical shear corresponded to high-frequency events and energy transfers from tidal frequencies to high frequencies associated with turbulent mixing.https://www.mdpi.com/2072-4292/14/11/2570internal tidesspatiotemporal variationEast China Seamodal structureenergy cascade |
| spellingShingle | Weidong Wang Robin Robertson Yang Wang Chen Zhao Zhanjiu Hao Baoshu Yin Zhenhua Xu Distinct Variability between Semidiurnal and Diurnal Internal Tides at the East China Sea Shelf Remote Sensing internal tides spatiotemporal variation East China Sea modal structure energy cascade |
| title | Distinct Variability between Semidiurnal and Diurnal Internal Tides at the East China Sea Shelf |
| title_full | Distinct Variability between Semidiurnal and Diurnal Internal Tides at the East China Sea Shelf |
| title_fullStr | Distinct Variability between Semidiurnal and Diurnal Internal Tides at the East China Sea Shelf |
| title_full_unstemmed | Distinct Variability between Semidiurnal and Diurnal Internal Tides at the East China Sea Shelf |
| title_short | Distinct Variability between Semidiurnal and Diurnal Internal Tides at the East China Sea Shelf |
| title_sort | distinct variability between semidiurnal and diurnal internal tides at the east china sea shelf |
| topic | internal tides spatiotemporal variation East China Sea modal structure energy cascade |
| url | https://www.mdpi.com/2072-4292/14/11/2570 |
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