Observation of Semi-diurnal Internal Tides and Near-inertial Waves at the Shelf Break of the East China Sea
1
조회
0
다운로드
1
인용
0
참고문헌
키워드
초록
Semi-diurnal internal tides and near-inertial waves are investigated using moored current meter measurements at four sites along the shelf break of the East China Sea during August 1987 and May-June 1988. Each mooring is equipped with four current meters spanning from near surface to near bottom. Spectral analyses of all current data reveal dominant spectra at the semi-diurnal frequency band, where the upper and lower current measurements show out-of-phase relationship between them with significant coherences. These are consistent with typical characteristics of the first-mode semi-diurnal internal tide. Strong intensification of the near-bottom baroclinic currents is observed only at one site, where the ratio of the bottom slope to the slope of the internal-wave characteristics at the semi-diurnal frequency is close to unity. An energetic near-inertial wave event is observed during the first half of May-June 1988 observation at two mooring sites. Rotary spectra reveal that the most dominant signal is clockwise rotating motion at the near-inertial frequency band. Upward phase and downward energy propagations, shown in time-depth contour plots of near-inertial bandpass filtered currents, are confirmed by cross correlations between the upper- and lower-layer current measurements. The upward-propagating phase speed is estimated to be about 0.13 cm s−1 at both sites. Significant coherences and in-phase relationships of near-inertial currents at the same or similar depths between the two sites are observed in spite of their long distance of about 110 km.
Abstract
Semi-diurnal internal tides and near-inertial waves are investigated using moored current meter measurements at four sites along the shelf break of the East China Sea during August 1987 and May-June 1988. Each mooring is equipped with four current meters spanning from near surface to near bottom. Spectral analyses of all current data reveal dominant spectra at the semi-diurnal frequency band, where the upper and lower current measurements show out-of-phase relationship between them with significant coherences. These are consistent with typical characteristics of the first-mode semi-diurnal internal tide. Strong intensification of the near-bottom baroclinic currents is observed only at one site, where the ratio of the bottom slope to the slope of the internal-wave characteristics at the semi-diurnal frequency is close to unity. An energetic near-inertial wave event is observed during the first half of May-June 1988 observation at two mooring sites. Rotary spectra reveal that the most dominant signal is clockwise rotating motion at the near-inertial frequency band. Upward phase and downward energy propagations, shown in time-depth contour plots of near-inertial bandpass filtered currents, are confirmed by cross correlations between the upper- and lower-layer current measurements. The upward-propagating phase speed is estimated to be about 0.13 cm s−1 at both sites. Significant coherences and in-phase relationships of near-inertial currents at the same or similar depths between the two sites are observed in spite of their long distance of about 110 km.
참고문헌 (31)
- Anderson I, "Near-inertial motions off the oregon coast", J Geophys Res, 88, pp.5960~5972 (1983)
- Baines PG, "On internal tide generation models", Deep- Sea Res, 29, pp.307~338 (1982)
- Baines PG, "Internal tides, internal waves, and near inertial motions in Baroclinic processes on continental shelves", pp.19~32 (1986), American Geophysical Union
- Chen C, "Near-inertial oscillations over the Texas-Louisiana shelf", J Geophys Res, 101, pp.3509~3524 (1996)
- Choi BH, "A tidal model of the Yellow Sea and the Eastern China Sea", pp.72~ (1980), KORDI
- Emery WJ, "Data analysis methods in physical oceanography, 2nd edn", pp.638~ (2001), Elsevier
- Gonella J, "Alocal study of inertial oscillations in the upper layers of the ocean", Deep-Sea Res, 18, pp.775~788 (1971)
- Guo BS, "Kuroshio warm filament and source of warm water of the Tsushima Current", Proceedings of Japan China joint symposium of the cooperative study on the Kuroshio, pp.112~127 (1989)
- Holloway PE, "Internal tides on the australian northwest shelf: a preliminary investigation", J Phys Oceanogr, 13, pp.1357~1370 (1983)
- Holloway PE, "On the semidiurnal internal tide at a shelf-break region on the australian northwest shelf", J Phys Oceanogr, 14, pp.1787~1799 (1984)
- Holloway PE, "A comparison of semidiurnal internal tides from different bathymetric locations on the australian northwest shelf", J Phys Oceanogr, 15, pp.240~251 (1985)
- Huthnance JM, "Tidal currents in the northwest African upwelling region", Deep-Sea Res, 29, pp.285~306 (1982)
- Jacobs GA, "Inertial oscillations in the Korea Strait", J Geophys Res, 106(26), pp.943~958 (2001)
- Ocean circulation and material flux of the East China Sea (2nd Year) -Eastern East China Sea, "KORDI", KORDI, 378~, pp.BSCN 00278-901-1 (1996)
- Kundu PK, "An analysisof inertial oscillations observed near oregon coast", J Phys Oceanogr, 6, pp.879~893 (1976)
- Kuroda Y, "Observation of internal tides in the East China Sea with an underwater sliding vehicle", J Geophys Res, 100, pp.10801~10816 (1995)
- Larsen LH, "East China Sea tide currents", Cont Shelf Res, 4, pp.77~103 (1985)
- Leaman KD, "Observations on the vertical polarization and energy flux of near-inertial waves", J Phys Oceanogr, 6, pp.894~908 (1976)
- Lie HJ, "Near-inertial current oscillations off the mideast coast of Korea", Prog Oceanogr, 21, pp.241~253 (1988)
- Lie HJ, "Recent advances in understanding the circulation and hydrography of the East China Sea", Fish Oceanogr, 11, pp.318~328 (2002)
- Matsuno TT, "Small scale internal waves and turbulent fluctuations near the continental shelf break in the East China Sea", J Oceanogr, 53, pp.259~269 (1997)
- Millot C, "Inertial oscillations on the continental shelf of the Gulf of lions: observations and theory", J Phys Oceanogr, 11, pp.639~657 (1981)
- Niwa Y, "Response of the deep ocean internal wave field to traveling midlatitude storms as observed in long-term current measurements", J Geophys Res, 104, pp.10981~10989 (1999)
- Niwa Y, "Three-dimensional numerical simulation of M2 internal tides in the East China Sea", J Geophys Res, 109, pp.C04027~ (2004)[DOI]
- Munk W, "Internal wave sand small-scale process in Evolution of Physical Oceanography", pp.264~291 (1981), MIT Press
- Park JH, "Near-inertial oscillations interacting with mesoscale circulation in the southwestern Japan", East Sea, 2005, pp.32, L10611~
- Park JH, "Internal tides in the southwestern Japan", East Sea, 2006, pp.36, 22~34
- Park JH, "Distribution of deep near-inertial waves observed in the Kuroshio extension", J Oceanogr, 66, pp.709~717 (2010)
- Phillips OM, "The dynamics of the upper ocean, 2nd edn", pp.344~, Cambridge University Press
- Pollard RT, "On the generation by winds of inertial waves in the ocean", Deep-Sea Res, 17, pp.795~812 (1970)
- Song W, "A study on the source of the Tsushima warm current water", Proceedings of Japan China joint symposium of the cooperative study on the Kuroshio, pp.99~111 (1989)