Research U.S. JGOFS Program Description The U.S. JGOFS program has consisted of six cooperating, complementary activity elements: time-series measurements at Hawaii and Bermuda, process studies, global surveys, synthesis and modeling efforts and data management. U.S. JGOFS is the U.S. national program of JGOFS, an international program sponsored by the Scientific Committee on Oceanic Research (SCOR) and the International Geosphere-Biosphere Programme (IGBP). U.S JGOFS is also an element of the U.S. Global Change Research program. The early history and broad framework of the U.S. JGOFS program has been described in a Science Plan (Long-Range Plan, U.S. JGOFS, 1990). The Plan includes a full description of the JGOFS program elements. A brief summary of those program elements appears below. Process Studies: The objective of the process studies component was to target key process links in models of the oceanic biogeochemical system and enhance our causal understanding of the processes. The goal of the process-oriented studies was to provide a mechanistic understanding of ocean processes in sufficient detail to predict and stimulate biogeochemical fluxes at representative sites in the ocean. Plans called for the deployment of moored arrays and detailed cruise operations in well-defined boxes at strategic oceanic locations. The U.S. participated in the four major JGOFS Process Studies and data reported from those studies appears on this volume. North Atlantic Bloom Experiment (NABE) conducted during 1989 in the North Atlantic at 20°W Equatorial Pacific Process Study (EqPac) conducted during 1992 from 12°N to 12°S at 140°W Arabian Sea Process Study conducted during 1994-1996 in the northwest Indian Ocean Antarctic Environment and Southern Ocean Process Study (AESOPS) conducted during 1996-1998 in the southwest Pacific sector of the Southern Ocean Data Management: The Data Management Office (DMO) was developed to meet the data management needs of U.S. JGOFS. During the U.S. JGOFS program, the DMO managed a web-based data server system which provided access to U.S. JGOFS data sets and information generated from the program's complementary elements. The remaining components of the U.S. JGOFS program are briefly described below and their results have been or will be published elsewhere. Time-series: Starting in 1988, JGOFS initiated two time-series measurement programs at Hawaii and Bermuda time series stations (HOT and BATS, respectively). The objective of the time-series effort is to provide well-sampled seasonal resolution of biogeochemical variability at a limited number of ocean observatories, provide support and background measurements for process-oriented research, as well as test and validate observations for biogeochemical models. The HOT and BATS records now span a period greater than 10 years with well over 100 successful cruises at each site and permanent moorings in place to assess ocean variability in the oligotrophic ocean. CO2 Survey: The rationale for the large-scale survey component of JGOFS is to provide a composite, basin to global scale, biogeochemical view of the ocean. The large-scale survey of basin-to-global oceanic CO2 parameters conducted as part of the WOCE Hydrographic Program cruises is a major component of the JGOFS survey program element. Satellite Observations of Ocean Color: Satellites can provide a large-scale view of the ocean. In particular, the ocean color sensor Sea-viewing Wide Field Sensor (SeaWiFS) is of interest to JGOFS due to its ability to measure surface chlorophyll distribution. Synthesis and Modeling: The main objective of the Synthesis and Modeling Project (SMP) is to synthesize knowledge gained from the U.S. JGOFS and related studies into models that reflect our current understanding of the ocean carbon cycle and its associated uncertainties. In particular, the processes that control carbon partitioning among ocean reservoirs, and the implications on ocean/atmosphere carbon exchange, are emphasized.