Chinese Journal of Oceanology and Limnology

, Volume 27, Issue 4, pp 955-965

First online:

A quasi-synoptic interpretation of water mass distribution and circulation in the western North Pacific II: Circulation

  • Lingling Xie谢玲玲Affiliated withPhysical Oceanography Laboratory, Ocean University of China Email author 
  • , Jiwei Tian田纪伟Affiliated withPhysical Oceanography Laboratory, Ocean University of China
  • , Dunxin Hu胡敦欣Affiliated withInstitute of Oceanography, Chinese Academia Science
  • , Fan Wang王凡Affiliated withInstitute of Oceanography, Chinese Academia Science

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Using the data of conductivity-temperature-depth (CTD) intensive observations conducted during Oct.–Nov. 2005, this study provides the first three-dimension quasi-synoptic description of the circulation in the western North Pacific. Several novel phenomena are revealed, especially in the deep ocean where earlier observations were very sparse. During the observations, the North Equatorial Current (NEC) splits at about 12°N near the sea surface. This bifurcation shifts northward with depth, reaching about 20°N at 1 000 m, and then remains nearly unchanged to as deep as 2 000 m. The Luzon Undercurrent (LUC), emerging below the Kuroshio from about 21°N, intensifies southward, with its upper boundary surfacing around 12°N. From there, part of the LUC separates from the coast, while the rest continues southward to join the Mindanao Current (MC). The MC extends to 2 000 m near the coast, and appears to be closely related to the subsurface cyclonic eddies which overlap low-salinity water from the North Pacific. The Mindanao Undercurrent (MUC), carrying waters from the South Pacific, shifts eastward upon approaching the Mindanao coast and eventually becomes part of the eastward undercurrent between 10°N and 12°N at 130°E. In the upper 2 000 dbar, the total westward transport across 130°E between 7.5°N and 18°N reaches 65.4 Sv (1 Sv = 10−6 m3s−1), the northward transport across 18°N from Luzon coast to 130°E is up to 35.0 Sv, and the southward transport across 7.5°N from Mindanao coast to 130°E is 27.9 Sv.


North Pacific North Equatorial Current (NEC) Luzon Undercurrent (LUC) Mindanao Undercurrent (MUC) volume transport