Detection of 17.5‐day period meridional current oscillations in the equatorial western Pacific Ocean during 1985

Abstract

The first long term, near equatorial, near surface moored current measurements recorded in the Pacific Ocean west of 160°W were made at 0°, 150°E during 2 August 1985–1 February 1986. These data revealed 17.5‐day period oscillations of the meridional current. Prior to these measurements, these waves had only been observed eastward of about 165°W, which also was the westernmost extent of their appearance in ocean general circulation model simulations. The 17.5‐day period waves also occurred in simultaneous current measurements at 140°W, where the wave amplitude was 3 times greater. At both sites the 17.5‐day period wave amplitude was more than 50% of the record‐length standard deviations of the meridional current component. A wider spectral bandwidth and a smaller tendency towards rectilinear motion occurred at 150°E than at 140°W.