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Proceedings Paper

Comparison of SeaWiFS on-orbit lunar and vicarious calibrations
Author(s): Robert E. Eplee; Sean W. Bailey; Robert A. Barnes; Hugh H. Kieffer; Charles R. McClain
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Paper Abstract

The NASA Ocean Biology Processing Group's Calibration and Validation Team has used monthly lunar calibrations of SeaWiFS to establish and maintain the on-orbit radiometric stability of instrument at the 0.1% level over its 9-year mission. The Cal/Val Team has compared the SeaWiFS lunar observations with the USGS ROLO photometric model of the Moon to verify the long-term stability of the SeaWiFS radiometric calibration. This stability has allowed the Team to apply a system-level vicarious calibration of the sensor/atmospheric calibration algorithm that is independent of time, yielding a single gain per band. SeaWiFS bands 1-6 (412-670 nm) are calibrated against water-leaving radiances measured by the Marine Optical Buoy (MOBY) that have been propagated to the top of the atmosphere. Band 7 (765 nm) is calibrated relative to band 8 (865 nm) so that the atmospheric correction algorithm selects maritime aerosol models over open ocean scenes. The long-term radiometric stability of SeaWiFS allows the Cal/Val Team to directly compare the mean residuals of the lunar observations from the ROLO model with the vicarious gains. A linear fit of the vicarious gains vs - (mean ROLO residual) for bands 1-6 gives a slope of 1.084 with a correlation of 0.980. The predicted mean ROLO residual for band 7, computed from the observed mean residual for band 8 and the vicarious gain for band 7, agrees with the observed mean residual for band 7 to within 0.5%. The radiometric stability of SeaWiFS allows the comparison of the prelaunch calibration of SeaWiFS, the calibration of MOBY, and the calibration of the USGS ROLO model. Such a comparison is of interest to other Earth-observing instruments which use the Moon as a calibration reference, such as MODIS, VIIRS, and ABI.

Paper Details

Date Published: 7 September 2006
PDF: 7 pages
Proc. SPIE 6296, Earth Observing Systems XI, 629610 (7 September 2006); doi: 10.1117/12.679168
Show Author Affiliations
Robert E. Eplee, Science Applications International Corp. (United States)
Sean W. Bailey, Futuretech Corp. (United States)
Robert A. Barnes, Science Applications International Corp. (United States)
Hugh H. Kieffer, Celestial Reasonings (United States)
Charles R. McClain, NASA Goddard Space Flight Ctr. (United States)

Published in SPIE Proceedings Vol. 6296:
Earth Observing Systems XI
James J. Butler, Editor(s)

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