Interannual variation of the water temperature and current velocity in the western equatorial region of the North Pacific
2006
Aoshima, T.(Nagasaki Univ. (Japan). Faculty of Fisheries) | Yoshimura, H. | Kanehara, H. | Morii, Y. | Yamawaki, N. | Murao, A. | Tsutsui, H. | Kinoshita, T. | Kamio, K. | Matsuno, T.
Oceanic current in the western region of the north equatorial Pacific was measured using ADPC and casting of XBT and CTD were also repeatedly carried out from 1991 to 2000. The geostrophic current velocity values, which were computed using XBT and CTD data with the depth of 480m used as a reference, were consistent with ADCP measured current velocities over a wide area, hence supporting the validity of the geostrophic current calculation with the reference depth of 480m. Data also showed strong eastward currents near 4 deg N and relatively weak westward currents near 10 deg N, these corresponding to the Equatorial Countercurrents and the North Equatorial Currents, respectively. Both ADCP-measurements and the geostrophic current velocities showed significant interannual variation of the Equatorial Countercurrents, which corresponds to the large variation in the main thermocline on the meridian lines. A correlation was observed between these variations and the Southern Oscillation Index, indicating that the interannual variation of the Equatorial Countercurrents was related to the El Nino/Southern Oscillation.
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