Wind-forced variability of upper ocean dynamics in the central equatorial pacific during PEQUOD

Abstract

Horizontal currants and dynamic height anomalies measured with a vertical profiler in the central equatorial Pacific during January 1981, February 1982 and April 1982 show significant changes in the upper ocean which are analyzed and discussed in terms of the vertical baroclinic modal structure. Most noticeable was a marked increase in average undercurrent speed and transport from February to April 1982, which was accompanied by a raising of sea level and a deepening of the pycnocline. This was due to an average increase in both first and second baroclinic modes. Over half of the increases of the first mode was due to a Kelvin wave pulse propagating eastward through the survey area at an estimated speed of 300 cm s-1. Evidence is presented which indicates that the wave was forced by a tropical storm in the western Pacific. The increase in the second baroclinic mode is attributed to the large-scale relaxation of the trade winds in the central and western Pacific during the spring of 1982.