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Proceedings Paper

Vegetation: in-flight multiangular calibration
Author(s): Bertrand Fougnie; Patrice J. Henry; Francois Cabot; Aime Meygret; Marie-Christine Laubies
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Paper Abstract

In the characterization of a space-borne wide field-of-view sensor, like Végétation, the multi-angular calibration is strongly complementary to the absolute calibration. It is defined as the process of estimating the sensitivity variations at different points of the Végétation wide field-of-view. This effect has to be integrated in the data processing. Pre-flight measurements were performed before launch, but because of heavy irradiations and aging of the different part of the sensor, it is necessary after launch to check and/or adjust the multi-angular calibration coefficients, gp. For this, the gp coefficients were split into three terms which required different methods: i/ first, the low-frequency term (gpLF) which refer to variation of the optic transmission which slightly decreases when viewing angle increases. The gpLF were verified using acquisitions over 20 desert sites for which TOA reflectances are accurately characterized (from ground measurements and POLDER/ADEOS-1 measurements). No in-flight variation of the gpLF were detected. ii/ second, the high-frequency term (gpHF) which refer to variation of the sensitivity of the elementary detectors. The gpHF were verified statistically using acquisitions over the Antarctica site and were accurately checked for the 4 spectral bands. ii/ third, the medium-frequency term (gpMF) which refer to various kinds of variation (optics, detectors...). The gpMF were verified during the 9pJpWDWLRQ like using the on-board calibration device (lamp profiles) and some small variations were identified (< 0.5% for B0, B2, B3 and ~1% for MIR). This aspect is still under investigation using acquisitions over Antarctica.

Paper Details

Date Published: 15 November 2000
PDF: 8 pages
Proc. SPIE 4135, Earth Observing Systems V, (15 November 2000); doi: 10.1117/12.494206
Show Author Affiliations
Bertrand Fougnie, Ctr. National d'Etudes Spatiales (France)
Patrice J. Henry, Ctr. National d'Etudes Spatiales (France)
Francois Cabot, Ctr. National d'Etudes Spatiales (France)
Aime Meygret, Ctr. National d'Etudes Spatiales (France)
Marie-Christine Laubies, Ctr. National d'Etudes Spatiales (France)

Published in SPIE Proceedings Vol. 4135:
Earth Observing Systems V
William L. Barnes, Editor(s)

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