U.S. Global Repeat Hydrographic/CO2/Tracer Surveys: Deep Ocean DOM Distribution and Dynamics

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With funding through this award, researchers at the University of Miami and at the University of California - Santa Barbara will continue their studies of dissolved organic carbon (DOC) in the world ocean as participants in the U.S. Repeat Hydrography Program. The primary scientific objective of the U.S. Repeat Hydrography program is to provide data for model calibration and validation, carbon system studies, heat and freshwater storage and flux studies, and deep and shallow water mass ventilation studies. This project seeks to further identify and understand processes controlling the deep ocean distribution of DOC. Three controls on DOC distributions of particular importance are: 1) Export of DOC from the surface layer with downward mixing of water masses, 2) non-conservative changes in DOC concentrations by biotic and abiotic processes, and 3) conservative changes in DOC concentrations due to mixing of water masses. To differentiate and assess these processes, the research team will make Level I (mandatory to the program) measurements of DOC on 4 major ocean sections (during 2006-2008) of the Hydrography Program. This project will have broader impacts in the study of the planetary carbon cycle in the context of global climatic change. The US Repeat Hydrography program results from the joint US CLIVAR and US Carbon Cycle Science Program call for a national program of observations along ocean sections to be integrated with international plans. The large-scale observation component of the US Carbon Cycle Science Plan defined a need for systematic observations of carbon in the ocean, capturing the spatial and long-term temporal variability in those variables. Students will be fully involved in implementation of the field component of the project. University of Miami undergraduate students have been on all of the Repeat Hydrography cruises to date. Participating on these cruises helps students meet curricular requirements and exposes them to interdisciplinary oceanography. This hands-on experience is invaluable to the learning process and has been rewarding to the students involved so far, providing excellent context for future work.