Vegetation: in-flight multiangular calibration

Bertrand Fougnie; Patrice J. Henry; Francois Cabot; Aime Meygret; Marie-Christine Laubies

doi:10.1117/12.494206

15 November 2000 Vegetation: in-flight multiangular calibration

Bertrand Fougnie, Patrice J. Henry, Francois Cabot, Aime Meygret, Marie-Christine Laubies

Proceedings Volume 4135, Earth Observing Systems V; (2000) https://doi.org/10.1117/12.494206
Event: International Symposium on Optical Science and Technology, 2000, San Diego, CA, United States

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.

Citation Download Citation

Bertrand Fougnie, Patrice J. Henry, Francois Cabot, Aime Meygret, and Marie-Christine Laubies "Vegetation: in-flight multiangular calibration", Proc. SPIE 4135, Earth Observing Systems V, (15 November 2000); https://doi.org/10.1117/12.494206

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