• Bingham, F. M., and R. Lukas, 1994: The southward intrusion of North Pacific Intermediate Water along the Mindanao coast. J. Phys. Oceanogr.,24, 141–154.

  • ——, and ——, 1995: The distribution of intermediate water in the western equatorial Pacific during January–February 1986. Deep-Sea Res. I,42, 1545–1573.

  • Bretherton, F. P., R. E. Davis, and C. B. Fandry, 1976: A technique for objective analysis and design of oceanographic experiments applied to MODE-73. Deep-Sea Res. I,23, 559–582.

  • Fine, R. A., R. Lukas, F. M. Bingham, M. J. Warner, and R. H. Gammon, 1994: The western equatorial Pacific is a water mass crossroads. J. Geophys. Res.,99, 25 063–25 080.

  • Gu, D., and, S. G. H. Philander, 1997: Interdecadal climate fluctuations that depend on exchange between the Tropics and extratropics. Science,275, 805–807.

  • Hautala, S. L., J. S. Reid, and N. Bray, 1996: The distribution and mixing of Pacific water masses in the Indonesian Seas. J. Geophys. Res.,101, 12 353–12 373.

  • Hu, D., M. Cui, T. Qu, and Y. Li, 1991: A subsurface northward current off Mindanao identified by dynamic calculation. Oceanography of Asian Marginal Seas, K. Takanao, Ed., No. 54, Elsevier Oceanogr. Series, Elsevier, 359–365.

  • Kashino, Y., M. Aoyama, T. Kawano, N. Hendiarti, Syaefudin, Y. Anantasena, K. Muneyama, and H. Watanabe, 1996: The water masses between Mindanao and New Guinea. J. Geophys. Res.,101, 12 391–12 400.

  • Levitus, S., and T. P. Boyer, 1994a: World Ocean Atlas 1994. Vol. 4: Temperature. NOAA Atlas NESDIS 4, U.S. Department of Commerce, 117 pp.

  • ——, and ——, 1994b: World Ocean Atlas 1994. Vol. 3: Salinity. NOAA Atlas NESDIS 3, U.S. Department of Commerce, 99 pp.

  • ——, and ——, 1994c: World Ocean Atlas 1994. Vol. 2: Oxygen. NOAA Atlas NESDIS 2, U.S. Department of Commerce, 186 pp.

  • Lu, P., and J. P. McCreary, 1995: Influence of the ITCZ on the flow of thermocline water from the subtropical to the equatorial Pacific Ocean. J. Phys. Oceanogr.,25, 3076–3088.

  • Lukas, R., E. Firing, P. Hacker, P. L. Richardson, C. A. Collins, R. Fine, and R. Gammon, 1991: Observations of the Mindanao Current during the Western Equatorial Pacific Ocean Circulation Study (WEPOCS). J. Geophys. Res.,96, 7098–7104.

  • Luyten, J. R., J. Pedlosky, and H. Stommel, 1983: The ventilation thermocline. J. Phys. Oceanogr.,13, 292–309.

  • Masumoto, Y., and T. Yamagata, 1991: Response of the western tropical Pacific to the Asian winter monsoon: The generation of the Mindanao Dome. J. Phys. Oceanogr.,21, 1386–1398.

  • Masuzawa, J., 1972: Water characteristics of the North Pacific central region. Kuroshio: Physical Aspects of the Japan Current, H. Stommel and K. Yoshida, Eds., University of Washington Press, 95–127.

  • McCreary, J. P., and P. Lu, 1994: On the interaction between the subtropical and the equatorial oceans: The subtropical cell. J. Phys. Oceanogr.,24, 466–497.

  • Nitani, H., 1972: Beginning of the Kuroshio. Kuroshio: Physical Aspects of the Japan Current, H. Stommel and K. Yoshida, Eds. University of Washington Press, 129–163.

  • Qiu, B., 1995: Why is the spreading of the North Pacific Intermediate Water confined on density surfaces around σθ = 26.8? J. Phys. Oceanogr.,25, 168–180.

  • ——, and R. Lukas, 1996: Seasonal and interannual variability of the North Equatorial Current, the Mindanao Current and the Kuroshio along the Pacific western boundary. J. Geophys. Res.,101, 12 315–12 330.

  • Qu, T., T. Kagimoto, and T. Yamagata, 1997: A subsurface countercurrent along the east coast of Luzon. Deep-Sea Res. I,44, 413–423.

  • ——, H. Mitsudera, and T. Yamagata, 1998: On the western boundary currents in the Philippine Sea. J. Geophys. Res.,103 (4), 7537–7548.

  • Reid, J. L., 1965: Intermediate waters of the Pacific Ocean. Johns Hopkins Oceanogr. Stud., Vol. 2, 85 pp.

  • ——, and R. S. Arthur, 1975: Interpretation of maps of geopotential anomaly for the deep Pacific Ocean, J. Mar. Res.,33 (Suppl.), 37–52.

  • Talley, L. D., 1993: Distribution and formation of North Pacific Intermediate Water. J. Phys. Oceanogr.,23, 517–537.

  • Toole, J. M., E. Zou, and R. C. Millard, 1988: On the circulation of the upper waters in the western equatorial Pacific Ocean. Deep-Sea Res. I,35, 1451–1482.

  • ——, R. C. Millard, Z. Wang, and S. Pu, 1990: Observations of the Pacific North Equatorial Current bifurcation at the Philippine Coast. J. Phys. Oceanogr.,20, 307–318.

  • Tsuchiya, M., 1968: Upper waters of the intertropical Pacific Ocean. Johns Hopkins Oceanogr. Stud., Vol. 4, 50 pp.

  • ——, R. Lukas, R. A. Fine, E. Firing, and E. Lindstrom, 1989: Source waters of the Pacific equatorial undercurrent. Progress in Oceanography, Vol. 23, Pergamon Press, 101–147.

  • Wijffels, S., E. Firing, and J. Toole, 1995: The mean structure and variability of the Mindanao Current at 8°N. J. Geophys. Res.,100, 18 421–18 435.

  • ——, M. M. Hall, T. Joyce, D. J. Torres, P. Hacker, and E. Firing, 1998: Multiple deep gyres of the western North Pacific: A WOCE section along 149°E. J. Geophys. Res., 103, 12 985–13 009.

  • Wyrtki, K., 1961: Physical oceanography of the southeast Asian waters. NAGA Report 2, Scripps Inst. of Oceanogr., University of California, San Diego, La Jolla, CA, 195 pp.

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A Climatology of the Circulation and Water Mass Distribution near the Philippine Coast

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  • 1 Japan Marine Science and Technology Center, Yokosuka, Japan, and International Pacific Research Center, SOEST, University of Hawaii, Honolulu
  • | 2 Department of Earth and Planetary Physics, University of Tokyo, Tokyo, Japan
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Abstract

This study provides a climatology of the circulation and water mass distribution by using historical data combined with observations from dozens of recent cruises near the Philippine coast. The most striking results are related to the poleward contraction of the subtropical gyre on denser surfaces, with the bifurcation of the North Equatorial Current moving from about 15°N in the upper thermocline to about 20°N at intermediate depths. Though time variability and the possible errors in the data are rather large, the Halmahera eddy (HE) is clearly seen in the climatic mean fields, lying at about 3°N, 130°E near the surface and reaching the Mindanao coast on density surfaces around 27.2σθ. It seems that the previously observed Mindanao Undercurrent is merely a component of the recirculation associated with the HE. North Pacific Tropical Water (NPTW) and Intermediate Water (NPIW) enter the western ocean with their extreme properties centered at 15° and 20°N, respectively, and continue southward as far as the southern tip of Mindanao along the western boundary. The influence of South Pacific sources becomes increasingly important with depth. Antarctic Intermediate Water (AAIW) is traced to about 12°N off Mindanao; but, there is little indication of a northward flow of AAIW farther north. Salinity extremes are also used as an indicator of NPTW and NPIW, and the primary result is that mixing of potential temperature and salinity are not jointly compensated, thus leading to an increase of density in NPTW and a decrease of density in NPIW in the flowpath from the North Pacific subtropical gyre to the Tropics along the Philippine coast.

* School of Ocean and Earth Science and Technology Contribution Number 4769.

Corresponding author address: Dr. Tangdong Qu, International Pacific Research Center, SOEST, University of Hawaii, 2525 Correa Rd., Honolulu, HI 96822.

Email: tangdong@soest.hawaii.edu

Abstract

This study provides a climatology of the circulation and water mass distribution by using historical data combined with observations from dozens of recent cruises near the Philippine coast. The most striking results are related to the poleward contraction of the subtropical gyre on denser surfaces, with the bifurcation of the North Equatorial Current moving from about 15°N in the upper thermocline to about 20°N at intermediate depths. Though time variability and the possible errors in the data are rather large, the Halmahera eddy (HE) is clearly seen in the climatic mean fields, lying at about 3°N, 130°E near the surface and reaching the Mindanao coast on density surfaces around 27.2σθ. It seems that the previously observed Mindanao Undercurrent is merely a component of the recirculation associated with the HE. North Pacific Tropical Water (NPTW) and Intermediate Water (NPIW) enter the western ocean with their extreme properties centered at 15° and 20°N, respectively, and continue southward as far as the southern tip of Mindanao along the western boundary. The influence of South Pacific sources becomes increasingly important with depth. Antarctic Intermediate Water (AAIW) is traced to about 12°N off Mindanao; but, there is little indication of a northward flow of AAIW farther north. Salinity extremes are also used as an indicator of NPTW and NPIW, and the primary result is that mixing of potential temperature and salinity are not jointly compensated, thus leading to an increase of density in NPTW and a decrease of density in NPIW in the flowpath from the North Pacific subtropical gyre to the Tropics along the Philippine coast.

* School of Ocean and Earth Science and Technology Contribution Number 4769.

Corresponding author address: Dr. Tangdong Qu, International Pacific Research Center, SOEST, University of Hawaii, 2525 Correa Rd., Honolulu, HI 96822.

Email: tangdong@soest.hawaii.edu

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