This work will be a study of processes that determine the structure and variability of the thermocline in the equatorial Pacific. Data describing the distribution of various chemical tracers will be compared with simulations made with a general circulation model. The aim is to improve modeling skill, gain a better understanding of the processes that transport tracers in the tropical Pacific, and to use the historical tracer data to identify variations in the tropical upper-ocean circulation. One of the tests of the model will be a comparison between the model's prediction of 14C concentration in the Pacific with 14C time series derived from corals in the tropical and subtropical Pacific.