A proposed CLIVAR program to put in place in the Pacific Ocean a long–term process experiment to test and improve dynamical models of the ocean processes that participate in climate variability. Specific program objectives are:

to obtain a quantitative description of the low–frequency, three–dimensional circulation and associated thermohaline structure of the upper Pacific Ocean with sufficient accuracy to measure advective fluxes and their divergences;

to test models of this circulation and its intrinsic modes of variability as well as those due to coupling with the atmosphere; and

to understand the processes that couple the tropical and subtropical Pacific oceanic gyres on climatic time scales and to test hypotheses about the role of the ocean in basin–scale variability on a broad range of climate time scales.