Sentinel-2A and 2B absolute calibration monitoring

• Published in: European Journal of Remote Sensing
• Main Authors: Charlotte Revel, Vincent Lonjou, Sébastien Marcq, Camille Desjardins, Bertrand Fougnie, Céline Coppolani-Delle Luche, Nicolas Guilleminot, Anne-Sophie Lacamp, Emmanuel Lourme, Christine Miquel, Xavier Lenot
• Format: Article in Journal/Newspaper
• Language: English
• Published: Taylor & Francis Group 2019
• Subjects: sentinel-2; vicarious calibration; multi-spectral calibration; cross-calibration; Oceanography; GC1-1581; Geology; QE1-996.5; Antarc*; Antarctica
• Online Access: https://doi.org/10.1080/22797254.2018.1562311; https://doaj.org/article/5ab0adb5c45a409787a9500695a167be

As part of the Copernicus program, Sentinel-2 is the optical imaging mission designed for the operational monitoring of land and coastal areas. It offers a unique combination of global coverage with a wide field of view, a high revisit capability (5 days with two satellites), a high resolution and multi-spectral imagery. CNES, the French Space Agency, was involved in the commissioning of both Sentinel-2 satellites and is currently working in collaboration with ESA on their long-term monitoring. This paper reviews all the techniques used to ensure an absolute calibration of the 13 spectral bands to better than 5% (the target is 3%) at TOA level. After a brief description of the mission and its related radiometric calibration scheme, we show how standard vicarious calibration methods based on acquisitions over natural targets (oceans, deserts, and Antarctica during winter) are used to check and improve the accuracy of the absolute calibration coefficients. Finally, the verification scheme, exploiting photometer in-situ measurements over the La Crau plain in France and Gobabeb in Namibia, is described. The paper concludes with a summary that includes spectral coherence, agreement between the results obtained with various calibration methods and temporal evolution.