An Evaluation of Oceanographic Radiometers and Deployment Methodologies

Stanford B. Hooker Laboratory for Hydrospheric Processes, NASA Goddard Space Flight Center, Greenbelt, Maryland

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Stephane Maritorena Institute for Computational Earth System Science, University of California, Santa Barbara, Santa Barbara, California

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Abstract

The primary objective of the Sea-viewing Wide Field-of-view Sensor (SeaWiFS) Project is to produce water-leaving radiances within an uncertainty of 5% in clear-water regions, and chlorophyll a concentrations within 35% over the range of 0.05–50 mg m−3. Any global mission, like SeaWiFS, requires validation data from a wide variety of investigators. This places a significant challenge on quantifying the total uncertainty associated with the in situ measurements, because each investigator follows slightly different practices when it comes to implementing all of the steps associated with collecting field data, even those with a prescribed set of protocols. This study uses data from multiple cruises to quantify the uncertainties associated with implementing data collection procedures while using different in-water optical instruments and deployment methods. A comprehensive approach is undertaken and includes (a) the use of a portable light source and in-water intercomparisons to monitor the stability of the field radiometers, (b) alternative methods for acquiring reference measurements, and (c) different techniques for making in-water profiles. Three optical systems had quadrature sum uncertainties sufficiently small to ensure a combined uncertainty for the spaceborne and in situ measurements within a total 5% vicarious calibration budget. A free-fall profiler using (relatively inexpensive) modular components performed best (2.7% quadrature sum uncertainty), although a more sophisticated (and comparatively expensive) profiler using integral components was very close and only 0.5% higher. A relatively inexpensive system deployed with a winch and crane was also close, but ship shadow contamination increased the quadrature sum uncertainty to approximately 3.4%.

Corresponding author address: Dr. Stanford B. Hooker, NASA Goddard Space Flight Center, Laboratory for Hydrospheric Processes, SeaWiFS Project, Code 970.2, Greenbelt, MD 20771.

Email: stan@ardbeg.gsfc.nasa.gov

Abstract

The primary objective of the Sea-viewing Wide Field-of-view Sensor (SeaWiFS) Project is to produce water-leaving radiances within an uncertainty of 5% in clear-water regions, and chlorophyll a concentrations within 35% over the range of 0.05–50 mg m−3. Any global mission, like SeaWiFS, requires validation data from a wide variety of investigators. This places a significant challenge on quantifying the total uncertainty associated with the in situ measurements, because each investigator follows slightly different practices when it comes to implementing all of the steps associated with collecting field data, even those with a prescribed set of protocols. This study uses data from multiple cruises to quantify the uncertainties associated with implementing data collection procedures while using different in-water optical instruments and deployment methods. A comprehensive approach is undertaken and includes (a) the use of a portable light source and in-water intercomparisons to monitor the stability of the field radiometers, (b) alternative methods for acquiring reference measurements, and (c) different techniques for making in-water profiles. Three optical systems had quadrature sum uncertainties sufficiently small to ensure a combined uncertainty for the spaceborne and in situ measurements within a total 5% vicarious calibration budget. A free-fall profiler using (relatively inexpensive) modular components performed best (2.7% quadrature sum uncertainty), although a more sophisticated (and comparatively expensive) profiler using integral components was very close and only 0.5% higher. A relatively inexpensive system deployed with a winch and crane was also close, but ship shadow contamination increased the quadrature sum uncertainty to approximately 3.4%.

Corresponding author address: Dr. Stanford B. Hooker, NASA Goddard Space Flight Center, Laboratory for Hydrospheric Processes, SeaWiFS Project, Code 970.2, Greenbelt, MD 20771.

Email: stan@ardbeg.gsfc.nasa.gov

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  • Aiken, J., and S. B. Hooker, 1997: The Atlantic Meridional Transect:Spatially extensive calibration and validation of optical properties and remotely-sensed measurements of ocean color. Backscatter,8, 8–11.

  • ——, and Coauthors, 1998: AMT-5 cruise report. NASA Tech. Memo. 1998-206892, Vol. 2, S. B. Hooker and E. R. Firestone, Eds., 113 pp. [Available from NASA Goddard Space Flight Center, Greenbelt, MD 20771.].

  • Gordon, H. R., 1985: Ship perturbation of irradiance measurements at sea. Part 1: Monte Carlo simulations. Appl. Opt.,24, 4172–4182.

  • Helliwell, W. S., G. N. Sullivan, B. MacDonald, and K. J. Voss, 1990:Ship shadowing: Model and data comparisons. Ocean Optics X, SPIE,1302, 55–71.

    • Crossref
    • Export Citation
  • Hooker, S. B., and W. E. Esaias, 1993: An overview of the SeaWiFS project. Eos, Trans. Amer. Geophys. Union,74, 241–246.

    • Crossref
    • Export Citation
  • ——, and J. Aiken, 1998: Calibration evaluation and radiometric testing of field radiometers with the SeaWiFS Quality Monitor (SQM). J. Atmos. Oceanic Technol.,15, 995–1007.

  • ——, and G. Lazin, 2000: The SeaBOARR-99 Field Campaign: SeaWiFS Postlaunch Tech. Rep. Series, NASA Tech. Memo. 2000-206892, S. B. Hooker and E. R. Firestone, Eds. [Available from NASA Goddard Space Flight Center, Greenbelt, MD 20771.].

  • ——, and C. R. McClain, 2000: A comprehensive plan for the calibration and validation of SeaWiFS data. Progress in Oceanography, in press.

  • ——, G. Zibordi, G. Lazin, and S. McLean, 1999: The SeaBOARR-98 Field Campaign. NASA Tech. Memo. 1999-206892, Vol. 3, S. B. Hooker and E. R. Firestone, Eds., 40 pp. [Available from NASA Goddard Space Flight Center, Greenbelt, MD 20771.].

  • ——, S. McLean, J. Sherman, M. Small, and G. Zibordi, 2000: The Seventh SeaWiFS Intercalibration Round-Robin Experiment (SIRREX-7), March 1999: SeaWiFS Postlaunch Tech. Rep. Series, NASA Tech. Memo. 2000-206892, S. B. Hooker and E. R. Firestone, Eds., Vol. 13, in press. [Available from NASA Goddard Space Flight Center, Greenbelt, MD 20771.].

  • Johnson, B. C., P.-S. Shaw, S. B. Hooker, and D. Lynch, 1998: Radiometric and engineering performance of the SeaWiFS Quality Monitor (SQM): A portable light source for field radiometers. J. Atmos. Oceanic Technol.,15, 1008–1022.

    • Crossref
    • Export Citation
  • ——, and Coauthors, 1999: The Fifth SeaWiFS Intercalibration Round-Robin Experiment (SIRREX-5), July 1996. NASA Tech. Memo. 2000-206892, Vol. 7, S. B. Hooker and E. R. Firestone, Eds. [Available from NASA Goddard Space Flight Center, Greenbelt, MD 20771.].

  • Joint Global Ocean Flux Study, 1991: JGOFS core measurements protocols. JGOFS Report No. 6, Scientific Committee on Oceanic Research, 40 pp. [Available from U.S. JGOFS Planning Institution, Woods Hole, MA 02543.].

  • McClain, C. R., W. E. Esaias, W. Barnes, B. Guenther, D. Endres, S. B. Hooker, G. Mitchell, and R. Barnes, 1992: Calibration and validation plan for SeaWiFS. NASA Tech. Memo. 104566, Vol. 3, S. B. Hooker and E. R. Firestone, Eds., 41 pp. [Available from NASA Goddard Space Flight Center, Greenbelt, MD 20771.].

  • ——, M. L. Cleave, G. C. Feldman, W. W. Gregg, and S. B. Hooker, 1998: Science quality SeaWiFS data for global biosphere research. Sea Technol.,39, 10–15.

  • Morel, A., and L. Prieur, 1977: Analysis of variations in ocean color. Limnol. Oceanogr.,22, 709–722.

    • Crossref
    • Export Citation
  • Mueller, J. L., and R. W. Austin, 1992: Ocean optics protocols for SeaWiFS validation. NASA Tech. Memo. 104566, Vol. 5, S. B. Hooker and E. R. Firestone, Eds., 45 pp. [Available from NASA Goddard Space Flight Center, Greenbelt, MD 20771.].

  • ——, and ——, 1995: Ocean optics protocols for SeaWiFS validation, revision 1. NASA Tech. Memo. 104566, Vol. 25, S. B. Hooker, E. R. Firestone, and J. G. Acker, Eds., 66 pp. [Available from NASA Goddard Space Flight Center, Greenbelt, MD 20771.].

  • ——, B. C. Johnson, C. L. Cromer, S. B. Hooker, J. T. McLean, and S. F. Biggar, 1996: The Third SeaWiFS Intercalibration Round-Robin Experiment, SIRREX-3, September 1994. NASA Tech. Memo. 104566, Vol. 34, S. B. Hooker, E. R. Firestone, and J. G. Acker, Eds., 78 pp. [Available from NASA Goddard Space Flight Center, Greenbelt, MD 20771.].

  • Neckel, H., and D. Labs, 1984: The solar radiation between 3300 and 12 500. Solar Phys.,90, 205–258.

    • Crossref
    • Export Citation
  • Press, W. H., and S. A. Teukolsky, 1992: Fitting straight line data with errors in both coordinates. Comput. Phys.,6, 274–276.

    • Crossref
    • Export Citation
  • Ricker, W. E., 1973: Linear regressions in fishery research. J. Fish. Res. Board Canada,30, 409–434.

    • Crossref
    • Export Citation
  • Shaw, P.-S., B. C. Johnson, S. B. Hooker, and D. Lynch, 1997: The SeaWiFS Quality Monitor—A portable field calibrator light source. Proc. SPIE,2963, 772–776.

    • Crossref
    • Export Citation
  • Siegel, D. A., M. C. O’Brien, J. C. Sorensen, D. A. Konnoff, E. A. Brody, J. L. Mueller, C. O. Davis, W. J. Rhea, and S. B. Hooker, 1995: Results of the SeaWiFS Data Analysis Round-Robin (DARR-94), July 1994. NASA Tech. Memo. 104566, Vol. 26, S. B. Hooker and E. R. Firestone, Eds., 58 pp. [Available from NASA Goddard Space Flight Center, Greenbelt, MD 20771.].

  • Voss, K. J., J. W. Nolten, and G. D. Edwards, 1986: Ship shadow effects on apparent optical properties. Ocean Optics VIII, SPIE,637, 186–190.

    • Crossref
    • Export Citation
  • Waters, K. J., R. C. Smith, and M. R. Lewis, 1990: Avoiding ship induced light-field perturbation in the determination of oceanic optical properties. Oceanography,3, 18–21.

    • Crossref
    • Export Citation
  • Weir, C. T., D. A. Siegel, D. W. Menzies, and A. F. Michaels, 1995:In situ evaluation of a ship’s shadow. Case Studies for SeaWIFS Calibration and Validation, Part 3, NASA Tech. Memo. 104566, Vol. 27, S. B. Hooker, E. R. Firestone, and J. G. Acker, Eds., 25–33. [Available from NASA Goddard Space Flight Center, Greenbelt, MD 20771.].

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