本研究使用一個南海區域的數值模式（South China Sea model）模擬向西移動的中尺度渦漩行為、冬季之南海暖流（South China Sea Warm Current）及颱風造成的海表面溫降，並解釋這些現象的動力過程與形成機制。由南海模式之海表面高度距平值顯示，起源於呂宋海峽附近之中尺度渦漩脫離後會向西移動，進而影響南海北部的水文及環流。此渦漩脫離的週期在冬天較短為40~50天，夏天較長為80~120天，此與黑潮入侵之季節性變化有關。南海模式也能成功地模擬出南海暖流。經由多個數值試驗得知，黑潮的存在並不會影響南海暖流的形成與否。冬季時東北季風的間歇性減弱（wind relexation），才是南海暖流產生的主要原因。也就是說，東北季風時期，海水會在東京灣（Gulf of Tonkin）岸邊堆積，使得海平面升高，待東北季風減弱後，海水回流進而形成南海暖流。我們也利用模式重新確認了暖流的發源處是在東京灣，而非過去所認為的海南島東南方。南海模式亦成功模擬了2000年夏季啟德颱風（Kai-Tak）在南海北部所造成的強烈海表面溫降。並利用數值試驗得知：湧升及垂直混合機制各自所占的表面降溫比例分別為62%與31%。啟德颱風能夠造成如此強烈之表面溫降原因為：一、颱風來臨前有異常淺的溫躍層存在，所以次表層的冷水較容易被帶到表面；二、颱風本身之移動速率較慢，因此由颱風引起之湧升效應更為強烈。

Based on a well-validated South China Sea (SCS) model, the characteristics of the westward-propagating mesoscale eddies, the formation mechanism of the South China Sea Warm Current (SCSWC), and the interplay between the upper ocean and typhoon Kai-Tak (2000) are studied. By virtue of a sequence of numerical experiments, the physical processes of those phenomena are further interpreted.
On the basis of the model simulation, the sea surface height anomaly demonstrates that westward-propagating eddies originating in the vicinity of the Luzon Strait can modulate the hydrography and circulation in the northern SCS. The eddy shedding periods in December and August are around 40~50 days and 80~120 days, respectively. The seasonal variability of the Kuroshio intrusion results in more eddies in winter than in summer.
Concerning the physical and geographical origins of the SCSWC, model experiments consistently point to the wind relaxation as the dominant mechanism. The Kuroshio intrusion also helps, but is not chiefly responsible. Tracing the SCSWC to the source, we identify the elevated sea level in the Gulf of Tonkin, induced by the northeast monsoon, as the ultimate driving force. The presence of Hainan Island bears little importance in generating the SCSWC.
An unusually drastic surface cooling induced by typhoon Kai-Tak (2000) in the northern SCS is well reproduced by the model. In the case of Kai-Tak, numerical experiments demonstrate that upwelling and entrainment (vertical mixing) respectively account for 62% and 31% of the sea surface temperature drop. The conditions for Kai-Tak are the anomalously shallow thermocline in 2000 that allows subsurface cooler water to be more easily brought up to the surface, and strong wind-induced upwelling by a slow-moving storm.

Archiving, Validation, and Interpretation of Satellite Data in Oceanography (AVISO), 1992: AVISO User Handbook: Merged TOPEX/Poseidon Products, Rep. AVI-NT-02-202-CN, ed. 2.1, Cent. D’Etudes Spatiales, Toulous, France.
Bender, M. A., Ginis, I., Kurihara, Y., 1993: Numerical simulations of tropical cyclone-ocean interaction with a high-resolution coupled model. Journal of Geophysical Research, 98 (D12), 23245-23263, doi: 10.1029/93JD02370.
Blumberg, A. F. and G. L. Mellor, 1987: A description of a three-dimensional coastal ocean circulation model. In: Heaps, N.S. (Ed.), Coastal and Estuarine Sciences 4: Three Dimensional Coastal Models. AGU, Washington, DC, 1-16 pp.
Caruso, M. J., G. G. Gawarkiewicz, R. C. Beardsley, 2006: Interannual variability of the Kuroshio intrusion in the South China Sea. Journal of Oceanography, 62, 559-575, doi: 10.1007/s10872-006-0076-0.
Centurioni L. R., P. P. Niiler and D.-K. Lee, 2004: Observations of inflow of Philippine Sea Water into the South China Sea through the Luzon Strait. Journal of Physical Oceanography 34, 113-121, doi: 10.1175/1520-0485(2004)034<0113:OOIOPS>2.0.CO;2.
Chao, S.-Y., P.-T. Shaw, and J. Wang, 1995: Wind relaxation as a possible cause of the South China Sea Warm Current. Journal of Oceanography, 51, 111-132, doi: 10.1007/BF02235940.
Chen, C.-C., F.-K. Shiah, S.-W. Chung, K.-K. Liu, 2006: Winter phytoplankton blooms in the shallow mixed layer of the South China Sea enhanced by upwelling. Journal of Marine Systems, 59, 97-110, doi: 10.1016/j.jmarsys.2005.09.002.
Chern, C.-S. and J. Wang, 2003: Numerical study of the upper-layer circulation in the South China Sea. Journal of Oceanography, 59, 11-24, doi: 10.1023/A:1022899920215.
Chiang, T.-L., C.-R. Wu, and S.-Y. Chao, 2008: Physical and geographical origins of the South China Sea Warm Current. Journal Geophysical Research, 113, C08028, doi: 10.1029/2008JC004794.
Chu, P. C., Veneziano, J. M., Fan, C., Carron, M. J., and Liu, W. T., 2000: Response of the South China Sea to Tropical Cyclone Ernie 1996. Journal of Geophysical Research, 105 (C6), 13991-14009, doi: 10.1029/2000JC900035.
Conkright, M. E., R. A. Locarnini, H. E. Garcia, T. D. O’Brien, T. P. Boyer, C. Stephens, J. I. Antonov, 2002: World Ocean Atlas 2001: Objective Analyses, Data Statistics, and Figures, CD-ROM Documentation. National Oceanographic Data Center, Silver Spring, MD, 17 pp.
Farris, A., and M. Wimbush, 1996: Wind-induced intrusion into the South China Sea. Journal of Oceanography 52, 771-784, doi: 10.1007/BF02239465.
Flather, R. A., 1976: A tidal model of the northwest European continental shelf. Memories de la Society Royal des Sciences de Liege 6 (10), 141-164.
Geisler, J. E., 1970: Linear theory of the response of a two-layer ocean to a moving hurricane. Geophysical Fluid Dynamics, 1, 249-272, doi: 10.1080/03091927009365774.
Guan, B., 1978: The warm current in the South China Sea - a current flowing against the wind in winter in the open sea off Guangdong province. Oceanologia et Limnologia Sinica, 9 (2), 117-127. (in Chinese with English abstract).
Guan, B., 1985: Some features of the temporal and spatial distributions of the “counter-wind” current in northern South China Sea in winter. Oceanologia et Limnologia Sinica, 16 (6), 429-438. (in Chinese with English abstract).
Hsin, Y.-C., C.-R. Wu, and P.-T. Shaw, 2008: Spatial and temporal variations of the Kuroshio east of Taiwan, 1982-2005: A numerical study. Journal of Geophysical Research, 113, C04002, doi: 10.1029/2007JC004485.
Ho, C.-R., Q. Zheng, Y. S. Soong, N.-J. Kuo, and J.-H. Hu, 2000: Seasonal variability of sea surface height in the South China Sea observed with TOPEX/Poseidon altimeter data. Journal of Geophysical Research, 105 (C6), 13981-13990, doi: 10.1029/2000JC900001.
Hsueh, Y., and L. Zhong, 2004: A pressure-driven South China Sea Warm Current. Journal of Geophysical Research, 109, C09014, doi: 10.1029/2004JC002374.
Hwang C., C.-R. Wu, and R. Kao, 2004: TOPEX/Poseidon observations of mesoscale eddies over the Subtropical Counter Current: kinematic characteristics of an anticyclonic eddy and a cyclonic eddy. Journal of Geophysical Research 109, C08013, doi: 10.1029/2003JC002026.
Jia, Y., Q. Liu, and W. Liu, 2005: Primary study of the mechanism of eddy shedding from the Kuroshio bend in Luzon Strait. Journal of Oceanography, 61, 1017-1027, doi: 10.1007/s10872-006-0018-x.
Jiang, X. P., Z. Zhong, J, J. Jiang, 2009: Upper ocean response of the South China Sea to Typhoon Krovanh (2003). Dynamics of Atmospheres and Oceans, 47 (1-3), 165-175, doi: 10.1016/j.dynatmoce.2008.09.005.
Kuo N.-J., Q. Zheng, and C.-R. Ho, 2000: Satellite observation of upwelling along the western coast of the South China Sea. Remote Sensing of Environment, 74, 463-470, doi: 10.1016/S0034-4257(00)00138-3.
Large, W. G. and S. Pond, 1981: Open ocean momentum flux measurements in moderate to strong winds. Journal Physical Oceanography, 11, 324-336. doi: 10.1175/1520-0485(1981)011<0324:OOMFMI>2.0.CO;2.
Li, L., W. D. Nowlin, and S. Jilan, 1998: Anticyclonic rings from the Kuroshio in the South China Sea. Deep-Sea Research 45, 1469-1482, doi: 10.1016/S0967-0637(98)00026-0.
Liang, W.-D, 2002: Study of upper ocean thermal and current variation in the South China Sea. Ph. D. dissertation, National Taiwan University, 125 pp.
Liang, W.-D., Y. J. Yang, T. Y. Tang, and W.-S. Chuang, 2008: Kuroshio in the Luzon Strait. Journal of Geophysical Research, 113, C08048, doi: 10.1029/2007JC004609.
Liang, W.-D., Tang, T. Y., Yang, Y. J., Ko, M. T., Chuang, W.-S., 2003. Upper-ocean current around Taiwan. Deep-Sea Research II 50, 1085-1105, doi: 10.1016/S0967-0645(03)00011-0.
Lin, I-I, W. T. Liu, C.-C. Wu, J. C. H. Chiang, and C.-R. Sui, 2003a: Satellite observations of modulation of surface winds by typhoon-induced upper ocean cooling. Geophysical Research Letters, 30 (3), 1131, doi: 10.1029/2002GL015674.
Lin, I-I, W. T. Liu, C.-C. Wu, G. T. F. Wong, C. Hu, Z. Chen, W.-D. Liang, Y. Yang, and K.-K. Liu, 2003b: New evidence for enhanced ocean primary production triggered by tropical cyclone. Geophysical Research Letters, 30 (13), 1718, doi: 10.1029/2003GL017141.
Liu, Q., C. Sun, and X. Jiang, 2009: Formation of spring warm water southwest of the Philippine Islands: winter monsoon wake effects. Dynamics of Atmospheres and Oceans, 47, 154-164, doi: 10.1016/j.dynatmoce.2008.08.003.
Mellor, G. L., 2004: Users guide for a three-dimensional, primitive equation, numerical ocean model. Program in Atmospheric and Oceanic Sciences. Princeton University, 56 pp.
Mellor, G. L., and T. Yamada, 1982: Development of a turbulence closure model for geophysical fluid problems. Review of Geophysics and Space Physics 20, 851-875, doi: 10.1029/RG020i004p00851.
Metzger, E. J., 2003: Upper ocean sensitivity to wind forcing in the South China Sea. Journal of Oceanography, 59, 783-798, doi: 10.1023/B:JOCE.0000009570.41358.c5.
Metzger, E. J., and H. E. Hurlburt, 2001: The nondeterministic nature of Kuroshio penetration and eddy shedding in the South China Sea. Journal of Physical Oceanography 31, 1712-1732, doi: 10.1175/1520-0485(2001)031<1712:TNNOKP>2.0.CO;2.
Milliff, R. F., W.G. Large, J. Morzel, G. Danabasoglu, and T. M. Chin, 1999: Ocean general circulation model sensitivity to forcing from scatterometer winds. Journal of Geophysical Research 104, 11337-11358, doi: 10.1029/1998JC900045.
Nitani H., 1972: Beginning of the Kuroshio, In: Stommel, H., Yoshida, K. (Eds.), Kuroshio, Physical Aspects of the Japan Current. University of Washington Press, Washington DC, 129-163 pp.
Oey, L.-Y., T. Ezer, D.-P. Wang, S.-J. Fan, and X.-Q. Yin, 2006: Loop Current warming by Hurricane Wilma. Geophysical Research Letters, 33, L08613, doi: 10.1029/2006GL025873.
Oey, L.-Y., T. Ezer, D.-P. Wang, X.-Q. Yin, and S.-J. Fan, 2007: Hurricane-induced motions and interaction with ocean currents. Continental Shelf Research, 27, 1249-1263, doi: 10.1016/j.csr.2007.01.008.
Price, J. F., 1981: Upper ocean response to a Hurricane. Journal of Physical Oceanography, 11 (2), 153-175, doi: 10.1175/1520-0485(1981)011<0153:UORTAH>2.0.CO;2.
Qu, T. 2000: Upper-layer circulation in the South China Sea. Journal of Physical Oceanography 30, 1450-1460, doi: 10.1175/1520-0485(2000)030<1450:ULCITS>2.0.CO;2.
Qu, T., 2002: Evidence for water exchange between the South China Sea and the Pacific Ocean through the Luzon Strait. Acta Oceanol. Sinica, 21, 175-185.
Qu, T. and R. Lukas, 2003: The bifurcation of the North Equatorial Current in the Pacific. Journal of Physical Oceanography 33, 5-18, doi: 10.1175/1520-0485(2003)033<0005:TBOTNE>2.0.CO;2.
Qu. T., H. Mitsudera, and T. Yamagata, 2000: Intrusion of the North Pacific waters into the South China Sea. Journal of Geophysical Research, 105 (C3), 6415-6424, doi: 10.1029/1999JC00323.
Roemmich, D. and J. Gilson, 2001: Eddy transport of heat and thermocline waters in the North Pacific: A key to interannual/decadal climate variability. Journal of Physical Oceanography 31, 675-687, doi: 10.1175/1520-0485(2001)031<0675:ETOHAT>2.0.CO;2.
Sarpkaya, T. and M. Isaacson, 1981: Mechanics of wave forced on offshore structures. Van Nostrand Reinhold Company, New York.
Shaw, P.-T., 1991: The seasonal variation of the intrusion of the Philippine Sea water into the South China Sea. Journal of Geophysical Research 96, 821-827, doi: 10.1029/90JC02367.
Shaw, P.-T. and S.-Y. Chao, 1994: Surface circulation in the South China Sea. Deep-Sea Resarch I, 41 (11/12), 1663-1683, doi: 10.1016/0967-0637(94)90067-1.
Shaw, P.-T., S.-Y. Chao, K.-K. Liu, S.-C. Pai, and C.-T. Liu, 1996: Winter upwelling off Luzon in the northeastern South China Sea. Journal of Geophysical Research, 101 (C7), 16435-16448, doi: 10.1029/96JC01064.
Smagorinsky, J., 1963: General circulation experiments with the primitive equations. I. The basic experiments. Monthly Weather Review, 91, 99-164, doi: 10.1175/1520-0493(1963)091<0099:GCEWTP>2.3.CO;2.
Trenberth, K. E., 1989: Surface wind stress from global atmospheric analyses. Ocean ’89 Proceedings, 1, 254-259.
Wang D., H. Xu, J. Lin, and J. Hu, 2008: Anticyclonic eddies in the northeastern South China Sea during winter 2003/2004. Journal of Oceanography, 64, 925-935, doi: 10.1007/s10872-008-0076-3.
Wang G., J. SU, Y. Ding, and D. Chen, 2007: Tropical cyclone genesis over the South China Sea. Journal of Marine System, 68, 318-326, doi: 10.1016/j.jmarsys.2006.12.002.
Wang L., C. J. Koblinsky, and S. Howden, 2000: Mesoscale variability in the South China Sea from the TOPEX/Poseidon altimetry data. Deep-Sea Research I, 47, 681-708, doi: 10.1016/S0967-0637(99)00068-0.
Wentz, F. J., C. Gentemann, D. Smith, and D. Chelton, 2000: Satellite measurements of sea surface temperature through clouds. Science, 288, 847-850, doi: 10.1126/science.288.5467.847.
Wu, C.-R. and C.-W. J. Chang, 2005: Interannual variability of the South China Sea in a data assimilation model. Geophysical Research Letters 32, L17611, doi: 10.1029/2005GL023798.
Wu, C.-R. and T.-L. Chiang, 2007: Mesoscale eddies in the northern South China Sea. Deep Sea Research II, 54, 1575-1588, doi: 10.1016/j.dsr2.2007.05.008.
Wu, C.-R. and Y.-C. Hsin, 2005: Volume transport through the Taiwan Strait: a numerical study. Terrestrial, Atmospheric and Oceanic Sciences 16, 2, 377-391.
Wu, C.-R., P.-T. Shaw, and S.-Y. Chao, 1998: Seasonal and interannual variations in the velocity field of the South China Sea. Journal of Oceanography, 54, 361-372, doi: 10.1007/BF02742620.
Wu, C.-R., P.-T. Shaw, and S.-Y. Chao, 1999: Assimilating altimetric data into a South China Sea. Journal of Geophysical Research, 104 (C12), 29987-30005, doi: 10.1029/1999JC900260.
Wu, C.-R., T. Y. Tang, and S. F. Lin, 2005: Intra-seasonal variation in the velocity field of the northeastern South China Sea. Continental Shelf Research 25, 2075-2083, doi: 10.1016/j.csr.2005.03.005.
Wu, C.-R., Y.-L. Chang, L.-Y. Oey, C.-W. J. Chang, and Y.-C. Hsin, 2008: Air-sea interaction between Tropical Cyclone Nari and Kuroshio. Geophysical Research Letters, 35, L12605, doi: 10.1029/2008GL033942.
Wyrtki, K., 1961: Physical oceanography of the southeast Asian waters. Scientific results of marine investigation of the South China Sea and the Gulf of Thailand 1959-1961. NAGA report Volume 2, Scripps Inst. Oceanography, La Jolla, California, 195pp.
Xiu, P., F. Chei, L. Shi, H. Xue, and Y. Chao, 2010: A census of eddy activities in the South China Sea during 1993-2007. Journal of Geophysical Reseatch, 115, C03012, doi: 10.1029/2009JC005657.
Xue, H., F. Chai, N. Pettigrew, D. Xu, M. Shi, and J. Xu, 2004: Kuroshio intrusion and the circulation in the South China Sea. Journal of Geophysical Research, 109, C02017, doi: 10.1029/2002JC001724.
Yang, K.-C., 2006: The non-persistent South China Sea Warm Current. Master dissertation, National Taiwan University, 48 pp.
Yang, J., D. Wu, and X. Lin, 2008: On the dynamics of the South China Sea Warm Current. Journal of Geophysical Research, 113, C08003, doi: 10.1029/2007JC004427.
Yaremchuk, M. and T. Qu, 2004: Seasonal variability of the large-scale currents near the coast of the Philippines. Journal of Physical Oceanography, 34, 844-855, doi: 10.1175/1520-0485(2004)034<0844:SVOTLC>2.0.CO;2.
Ye, L., 1994: On the mechanism of South China Sea warm Current and Kuroshio Branch in winter - Preliminary result of 3-D baroclinic experiments. Terrestrial, Atmospheric and Oceanic Sciences, 5(4), 597-610.
Yu, Z., S. Shen, J. P. McCreary, M. Yaremchuk, and R. Furue, 2007: South China Sea throughflow as evidenced by satellite images and numerical experiments. Geophysical Research Letters, 34, L01601, doi: 10.1029/2006GL028103.
Yuan, D., W. Han, and D. Hu, 2006: Surface Kuroshio path in the Luzon Strait area derived from satellite remote sensing data. Journal of Geophysical Research, 111, C11007, doi: 10.1029/2005JC003412.
Zheng, Z.-W., C.-R. Ho, and N.-J. Kuo, 2007: Geophysical Research Letters, 34, L11604, doi: 10.1029/2007GL030058.