Barotropic Tide in the Northeast South China Sea

Beardsley, Robert C.; Duda, Timothy F.; Lynch, James F.; Irish, James D.; Ramp, S.R.; Chiu, Ching‐Sang; Tang, Tie-Qiao; Yang, Yaming; Fang, Guohong

doi:10.1109/joe.2004.833226

Cited by 46 publications

(32 citation statements)

References 13 publications

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“…The barotropic M2 and S2 current ellipses turned clockwise in the onshelf direction, with a clear onshelf increase in current amplitude. The M2 and S2 transport ellipses also showed this clockwise veering, but with little change in amplitude, suggesting that the flow was approximately nondivergent in the direction of the ellipse orientation [20]. The M2 energy flux vector was generally closely aligned with the transport major axis and within 6% of its maximum value, a result of the small phase lag between high water and maximum transport.…”

Section: Summary Of Physical Oceanography Resultsmentioning

confidence: 87%

“…The tides in the area were mixed, with the O1 and K1 tidal currents dominant over the upper slope and the M2 tidal current becoming dominant over the shelf [20]. The tidal currents were elliptical at all sites, with clockwise turning with time with the possible exception of O1 and K1 constituents over the slope where the semi-minor axes were poorly resolved.…”

Section: Summary Of Physical Oceanography Resultsmentioning

confidence: 94%

“…The O1 and K1 current amplitudes tended to increase slightly northward toward the shelf break and then decrease toward shallower water over the shelf. The O1 and K1 transports decreased monotonically northward by a factor of 2 due to the sharp decrease in water depth from the deepest slope site to the shallowest shelf site [20]. The O1 and K1 energy fluxes were directed roughly westward over the slope and eastward over the midshelf.…”

Section: Summary Of Physical Oceanography Resultsmentioning

confidence: 96%

See 2 more Smart Citations

Research Highlights From the Asian Seas International Acoustics Experiment in the South China Sea

Lynch

Ramp²,

Chiu³

et al. 2004

IEEE J. Oceanic Eng.

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Section: Summary Of Physical Oceanography Resultsmentioning

confidence: 87%

Section: Summary Of Physical Oceanography Resultsmentioning

confidence: 94%

Section: Summary Of Physical Oceanography Resultsmentioning

confidence: 96%

See 1 more Smart Citation

Research Highlights From the Asian Seas International Acoustics Experiment in the South China Sea

Lynch

Ramp²,

Chiu³

et al. 2004

IEEE J. Oceanic Eng.

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“…Statistically speaking, the current magnitudes in the tidal band ranged from 40 to 60 cm s across the entire array with standard deviations from 15 to 22 cm s , much stronger than the mean currents yet much weaker than the internal waves. The tides are the subject of two related manuscripts in this volume on the barotropic [41] and baroclinic [2] tides. Noteworthy here is the relationship between the internal tide (period 12-24 h) and the observed large amplitude internal waves (period minutes to 2 h).…”

Section: A Oceanographic Contextmentioning

confidence: 99%

Internal Solitons in the Northeastern South China Sea Part I: Sources and Deep Water Propagation

Ramp

Tang²,

Duda³

et al. 2004

IEEE J. Oceanic Eng.

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344

321

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Abstract-A moored array of current, temperature, conductivity, and pressure sensors was deployed across the Chinese continental shelf and slope in support of the Asian Seas International Acoustics Experiment. The goal of the observations was to quantify the water column variability in order to understand the along-and across-shore low-frequency acoustic propagation in shallow water. The moorings were deployed from April 21-May 19, 2001 and sampled at 1-5 min intervals to capture the full range of temporal variability without aliasing the internal wave field. The dominant oceanographic signal by far was in fact the highly nonlinear internal waves (or solitons) which were generated near the Batan Islands in the Luzon Strait and propagated 485 km across deep water to the observation region. Dubbed trans-basin waves, to distinguish them from other, smaller nonlinear waves generated locally near the shelf break, these waves had amplitudes ranging from 29 to greater than 140 m and were among the largest such waves ever observed in the world's oceans. The waves arrived at the most offshore mooring in two clusters lasting 7-8 days each separated by five days when no waves were observed. Within each cluster, two types of waves arrived which have been named type-a and type-b. The type-a waves had greater amplitude than the type-b waves and arrived with remarkable regularity at the same time each day, 24 h apart. The type-b waves were weaker than the type-a waves, arrived an hour later each day, and generally consisted of a single soliton growing out of the center of the wave packet. Comparison with modeled barotropic tides from the generation region revealed that: 1) The two clusters were generated around the time of the spring tides in the Luzon strait; and 2) The type-a waves were generated on the strong side of the diurnal inequality while the type-b waves were generated on the weaker beat. The position of the Kuroshio intrusion into the Luzon Strait may modulate the strength of the waves being produced. As the waves shoaled, the huge lead solitons first split into two solitons then merged together into a broad region of thermocline depression at depths less than 120 m. Elevation waves sprang up behind them as they continued to propagate onshore. The elevation waves also grew out of regions where the locally-generated internal tide forced the main thermocline down near the bottom. The "critical T. Y. Tang is with the Institute of Oceanography, National Taiwan University, Taipei, ROC.H. point" where the upper and lower layers were equal was a good indicator of when the depression or elevation waves would form, however this was not a static point, but rather varied in both space and time according to the presence or absence of the internal tides and the incoming trans-basin waves themselves.

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“…1) extending from the inner shelf to the continental slope with the water depth increasing seaward from station S2 (approximately 70 m) toward station S7 (approximately 350 m) from April to May 2001. The data were examined by Beardsley et al (2004), Duda et al (2004), and many others studying barotropic and baroclinic tides as well as the characteristics of internal solitary waves. Moreover, the data facilitate the study of the spatial structure of subtidal currents on the shelf and shelf break.…”

Section: Fieldworkmentioning

confidence: 99%

Subtidal current structure and variability of the continental shelf and slope of the northern South China Sea

Tai¹,

Yang²,

Gawarkiewicz³

2017

Terr. Atmos. Ocean. Sci.

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The spatial structures and temporal variations in subtidal currents in the northern South China Sea (SCS) are quantified in this study using 20-day to 9-month measurements from eight acoustic Doppler current profiler moorings deployed on the shelf and slope. The moored observations demonstrated that subtidal currents varied considerably with no persistent current feature on the shelf or slope. In winter, transient northeastward subtidal flows appeared sporadically but only when the wind stress was lower than 1 dyne cm -2 . The potential transient along-shelf flow formation mechanisms during winter are attributed to the variation in cross-shelf and alongshelf sea levels. The variation in cross-shelf sea level is due to Ekman transports varying over a period of 100 h. The variation in cross-shelf sea level gradient induced by the wind generates an along-shelf geostrophic current. When the sea level gradient anomaly is negative (i.e., sea level anomaly increased seaward), a transient shelf current appears, whereas the opposite phenomenon occurs as the sea level anomaly decreases seaward. The variation in the along-shelf sea level is due to the along-shelf sea level setup or set down as a result of shelf water accumulation or reduction near Hainan Island over a period of approximately 400 h. Other possible factors affecting subtidal currents include fresh water inputs from the Taiwan Strait, typhoons and eddies in the northern SCS.

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Barotropic Tide in the Northeast South China Sea

Cited by 46 publications

References 13 publications

Research Highlights From the Asian Seas International Acoustics Experiment in the South China Sea

Research Highlights From the Asian Seas International Acoustics Experiment in the South China Sea

Internal Solitons in the Northeastern South China Sea Part I: Sources and Deep Water Propagation

Subtidal current structure and variability of the continental shelf and slope of the northern South China Sea

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