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The Moderate Resolution Imaging Spectroradiometer (MODIS) is currently flying on both the Terra and Aqua
satellite platforms. The Ocean Biology Processing Group (OBPG) at NASA Goddard Space Flight Center is
producing operational ocean color products from the MODIS-Aqua sensor; however, documented uncertainties
and instabilities in the prelaunch and on-orbit characterization have inhibited the production of similar products
from MODIS-Terra. In particular, the radiometric response of the 412-nm band has degraded by more than
40% over the 7-year mission lifespan, with similar though less extreme changes in the longer wavelengths. Furthermore,
the degradation trends are significantly different between the two mirror sides, which is likely a result
of asymmetric damage done to the mirror during prelaunch testing. These effects contribute to uncertainty in
our knowledge of instrument response versus incidence angle on the mirror and sensitivity with respect to polarization
of the observed radiance. In this paper, we examine the impact of apparent MODIS-Terra instrument
characterization errors on the derived ocean color products and show that residual errors in the current operational
calibration give rise to significant cross-scan artifacts, mirror-side differences, and detector-to-detector
striping in the retrieved water-leaving radiances. In addition, we describe OBPG efforts to reduce these artifacts
through statistical and vicarious instrument characterization, and show the quality of the resulting water-leaving
radiance retrievals relative to those derived from MODIS-Aqua.
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