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Validation of satellite primary productivity estimates using measurements of the oxygen isotope composition of dissolved O2.

Lauren Juranek, University of Washington School of Oceanography; NOAA-PMEL, laurie.juranek@noaa.gov (Presenting)
Paul Quay, University of Washington School of Oceanography, pdquay@u.washington.edu
David Munro, University of Washington School of Oceanography, dmunro@u.washington.edu
Cynthia Peacock, University of Washington School of Oceanography, cyngoat@u.washington.edu

Estimates of marine primary productivity (PP) are the foundation of the ocean’s carbon cycle and are essential to understanding biological controls of air-sea CO2 exchange. Satellite PP algorithms based on remotely-sensed ocean color or biomass provide globally synoptic coverage and are therefore essential tools for assessing future changes in marine PP. However, these estimates currently suffer from a lack of high quality in situ data for algorithm validation. We present new estimates of marine PP throughout the subtropical, tropical, and subpolar Pacific Ocean and the California Coast obtained using measurements of dissolved oxygen isotope ratios in surface seawater. Because this method does not require bottle incubations, only the collection of surface seawater, it can be readily applied to ships of opportunity and is therefore capable of providing repeated, near-synoptic estimates of marine PP useful for validation of satellite algorithms. We present 18 months of simultaneous bottle rate measurements (14C-PP and 18O-Gross PP, GPP) and oxygen isotope ratio (17&Delta) based GPP estimates at the Hawaii Ocean Time-series Study site used to prove the effectiveness of the 17&Delta method and understand the relationships between 14C-PP and GPP. We also show how container ship cruises across the Pacific Ocean and research cruises on the California coast (CalCOFI) can be used to provide repeated estimates of marine PP at a spatial resolution that would not be easily obtainable by traditional PP methodology (14C-PP). We find that GPP increases by a factor of ~4 between the subtropical and equatorial Pacific and by a factor of ~6 within 150 km of the California coast. We compare these results to two different satellite PP algorithm estimates (Behrenfeld and Falkowski, 1997; Behrenfeld et al., 2005) to evaluate algorithm performance.


NASA Carbon Cycle & Ecosystems Active Awards Represented by this Poster:

  • Award: NNG04GQ51H
    Start Date: 2004-09-15
     

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