R/V Revelle, cruise 1107, Lamon Bay, Kaohsiung to Kaohsiung, 18 May - 6 June 2011, Personnel exchange at Port Irene, Philippines on 19 May and 4 June

• Main Author: Gordon, Arnold L.
• Format: Report
• Language: unknown
• Published: Columbia University 2011
• Subjects: Oceanography; Arctic; Bering Strait; Pacific
• Online Access: https://dx.doi.org/10.7916/d8jq184q; https://academiccommons.columbia.edu/doi/10.7916/D8JQ184Q

The circulation within Lamon Bay (defined here as west of 124°E, south of 18°N, north of 14°N) is vigorous, with surface layer currents often between 1 and 2 kts. The Kuroshio at 18.35°N (northeastern tip of Luzon) was nearly 3 kts at the sea surface, and extended to ~350 m. Within Lamon Bay are 2 energetic gyres or dipoles that bracket a northwestward stream into the Kuroshio. These features extend to only 150-200 m. The cyclonic dipole is within the southern tier of Lamon Bay; the much more energetic anticyclonic dipole is to the north of the Kuroshio feeder stream. This sets up a bifurcation along the western boundary of Lamon Bay, near 16°-17°N, which is likely more relevant to the Kuroshio than the bifurcation near 13°N. The first occurrence of (what I would call) the Kuroshio is at the 16.5°N western boundary. The vorticity transfer linking the nascent Kuroshio to the dipoles needs to be considered in understanding the origin of the Kuroshio. The Lamon Bay dipole has a branch entering into Polillo Strait, and then exported from the shelf north of Calagua Island, introducing low salinity surface water into the Lamon Bay cyclonic dipole. Lamon Bay is a confluence of waters from different ocean regimes that then contribute to the Kuroshio. The Kuroshio off the northeastern point of Luzon is mainly drawn from North Pacific subtropical water (subtropical component of the North Equatorial Current) and western North Pacific Kuroshio recirculation. Input from the equatorial component of the North Equatorial Current, derived from the bifurcation near 13°N, is small. From continuity it is limited in the long-term to compensate for the loss of upper kilometer water form the North Pacific: Bering Strait export to the Arctic and export of North Pacific Intermediate water to the Mindanao Current; estimate: ~ 4 Sv. The Lamon Bay project mooring will provide 1-year record of the dipoles and Kuroshio feeder stream behavior; Lamon Bay 2012 cruise will provide another snapshot to test the concepts drawn from the Lamon Bay 2011 cruise.