Calibration and validation of Envisat MERIS part I: Vicarious calibration at Rail Road Valley Playa (NV)

On August 22, 2002, a vicarious calibration (VC) experiment of MERIS, a pushbroom imaging spectrometer on ESA’s ENVISAT, was performed. The purpose of this experiment was the acquisition of in-situ measurements of surface and atmospheric conditions over a bright, uniform target. These data were then used to compute top-of-atmosphere (TOA) radiances, which were correlated with the MERIS TOA radiances (Level 1b product), to determine the in-flight radiometric response of the on-orbit sensor. The Rail Road Valley Playa, NV, was the primary target chosen by the Optical Sciences Center, University of Arizona, and the Remote Sensing Laboratories, University of Zurich, for this experiment. The in-situ estimations of top-of-atmosphere radiances lie within less than 6% of the MERIS measurements, except for band 11 (760 nm) and band 15 (900 nm). The absolute uncertainty of the vicarious calibration experiment is estimated to be less than 3.36%. Based on the uncertainties of the vicarious calibration method and the calibration accuracies of MERIS, no recommendation to update the MERIS calibration may be given.