Vertical velocities and transports in the equatorial Pacific during 1993-99

Geostrophic and Ekman transports calculated from observations of subsurface thermal structure and surface winds are used to determine vertical velocit ies and transports as a function of time, depth, and longitude in the equat orial Pacific within 5 degreesS-5 degreesN, 165 degreesE-95W during 1993-99 via a box volume balance. The vertical transports are determined in boxes of 10 degrees of latitude by generally 15 degrees in longitude. The corresp onding vertical velocities represent a spatial average over these regions. Both the total vertical velocity and the cross-isopycnal component of the v ertical velocity (approximated by the cross-isothermal component) are calcu lated on seasonal and interannual timescales. For the eastern equatorial Pa cific (5 degreesS-5 degreesN, 155 degrees -95 degreesW) the mean vertical t ransport across 50 m is (24 +/- 3) x 10(6) m(3) s(-1). Variability in the v ertical velocity is large relative to the mean. On interannual timescales t his variability is well correlated with the local winds in the western port ion of the study area, while the correspondence is weaker in the east where wind variability is much smaller. At seasonal timescales there is good cor respondence between the vertical velocity and the local winds throughout th e study region. The cross-isothermal vertical velocity is significantly sma ller than the total vertical velocity, and the means of both compare well w ith the few historical estimates available.