Upper Ocean Heat and Salt Balances in the Western Equatorial Paci c in Response to the Intraseasonal Oscillation During TOGA COARE

Ming Feng
Roger Lukas
Peter Hacker
Robert A. Weller
Steven P. Anderson

School of Ocean and Earth Science and Technology
University of Hawaii
Honolulu, HI 96822

Woods Hole Oceanographic Institution
Woods Hole, MA, USA 02543


Abstract
During the TOGA COARE Intensive Observing Period (IOP) from November 1992 through February 1993, temperature, salinity and velocity profiles were repeatedly obtained within a 130~km times 130~km region near the center of the Intensive Flux Array (IFA) in the western equatorial Pacific warm pool. Together with high quality measurements of air-sea heat flux, rainrate, upper ocean microstructure, and penetrating solar radiation, they make up a unique dataset for upper ocean heat and freshwater budget studies. Three survey cruises sampled different phases of the Intraseasonal Oscillation (ISO) during the IOP. Temporal evolution and advective terms in the heat and salt balance equations, on time scale of three days and longer, are estimated using the survey data. The upper ocean (0--50 m) heat and salt budgets at the center of the IFA were estimated and are closed to within 10wm of observed air-sea heat fluxes and to within approximately 20% of observed rainrates during each of the three cruises. Generally, advection in the upper ocean can not be neglected during the IOP. Zonal advection alternates sign, but had a net warming and freshening tendency. Meridional advection decreased temperature and increased salinity in the surface layer, while vertical advection warmed and freshened the surface layer because of the general downwelling trend. Heat advection is as important as the net air-sea flux during the westerly wind burst time periods. The sub-ISO time scale upper ocean dynamics, such as the strong meridional advection caused by inertial motions, are found to have important contributions to the upper ocean heat and freshwater balances.


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