Short-Term Climatic Variability in the Volume Budget of the Western Tropical North Pacific Ocean during 1979–82

Abstract

Abstract Anomalous 14°C isotherm depth and anomalous geostrophic volume transport above the 14°C isotherm depth are calculated in the tropical Pacific for each bimonth of the four year period 1979 to 1982, based on 15 000 temperature/depth observations made by volunteer observing ships. The first two eigenfunctions (EOFs) of the anomalous 14°C isotherm depth, the anomalous zonal geostrophic volume transport, and the anomalous meridional Ekman volume transport explain 44%, 32% and 47% of their variances, respectively. Most of the variability explained by the first EOF is associated with the 1982–83 ENSO event. The EOFs indicate that a loss of anomalous volume above the 14°C isotherm in the western tropical North Pacific is correlated with an increase in anomalous volume in the eastern equatorial Pacific. There is a simultaneous intensification of anomalous eastward geostrophic currents across the width of the equatorial Pacific; however, from 150°E to 140°W there is also a simultaneous intensification of a...