HR: 08:45h
AN: OS31A-04    [Abstracts]
TI: Ocean Color Climate Records
AU: * Gregg, W
EM: watson.gregg@nasa.gov
AF: NASA/Global Modeling and Assimilation Office, Code 610.1, Greenbelt, MD 20771, United States
AB: Individual ocean color missions have finite lifetimes, so it is critical to produce a consistent time series across ocean color missions if we are to address fundamental questions of Earth science importance, especially how the ocean biogeochemical system is changing. Developing Ocean Color Climate Records (OCCR's), which meet the definitions of the National Research Council has been a challenge. Consistent algorithms and processing methodologies are considered essential for such data records, but our experience with SeaWiFS and MODIS- Aqua indicates that this is not enough. They differed by 10% globally in overlapping time segments, late 2002- 2004 (see McClain et al., 2006). For perspective, the maximum change in annual means over the entire SeaWiFS mission era was 5%, and this included an El Niño-La Niña transition. We define OCCR's to meet the broad definitions of NRC, but additionally impose more stringent requirements specific to the science of ocean color: 1) all mission-dependent biases removed or quantified, 2) no obvious interannual discontinuities unattributable to natural variability, 3) similar data quality and structure. Our overall plan is to look at the missions as a time series, and develop methodologies that maximize the usefulness of the time series. The primary mission-long problems are aerosols, calibration, and other residual biases. We provide solutions to these problems using consistent processing methodologies, in situ data fusion techniques, and data assimilation. Our criteria for success are: 1) Low bias as determined by in situ chlorophyll comparisons, with regression slope near unity, 2) No change in trends annually and globally and no discontinuities using contemporary, overlapping data, when one mission is substituted for another 3) Observed trends in agreement with related climate data trends 4) Comparison and broad agreement with coupled global ocean biology models 5) Methodological maturity 6) Community approval
DE: 0429 Climate dynamics (1620)
DE: 0480 Remote sensing
DE: 4815 Ecosystems, structure, dynamics, and modeling (0439)
DE: 4855 Phytoplankton
SC: Ocean Sciences [OS]
MN: 2007 Joint Assembly