Primary production in the ocean is important not only for the functioning of the marine ecosystem but also for its pivotal role in regulating sea-air exchange of carbon dioxide, the most important atmospheric greenhouse gas. In this study, the principal investigator will use an indirect method to determine the net annual oxygen production in the northwest Pacific Ocean by measuring eleven profiles of O2, N2, and Ar concentrations in the upper ocean at the Japanese Joint Global Ocean Flux Study (JGOFS) time-series station. The time-series station is located in what is probably the most biologically productive region of the North Pacific, and the oxygen flux estimates are expected to provide the first good estimates of the regional primary production. The PI will be taking advantage of a unique opportunity to participate in Japanese JGOFS cruises in this region between 1998 and 2000.