An attempt to perform inter-band calibration validation for Sentinel-2 using snowy sites such as DomeC in Antarctica

• Published in: Sensors, Systems, and Next-Generation Satellites XXIII
• Main Author: Viallefont-Robinet, Françoise
• Other Authors: DOTA, ONERA, Université de Toulouse Toulouse, ONERA-PRES Université de Toulouse
• Format: Conference Object
• Language: English
• Published: HAL CCSD 2019
• Subjects: INTER-BANDE; ETALONNAGE; VALIDATION; TELEDETECTION; SENTINEL 2; ANTARCTIQUE; ETALONNAGE RADIOMETRIQUE; CALIBRATION; [SPI]Engineering Sciences [physics]; [PHYS]Physics [physics]; Antarc*; Antarctic; Antarctica; Antarctique*
• Online Access: https://hal.science/hal-02409754; https://hal.science/hal-02409754/document; https://hal.science/hal-02409754/file/DOTA19188.1571908876_preprint.pdf; https://doi.org/10.1117/12.2532851

International audience In the frame of the monitoring of Sentinel 2 MSI sensors in orbit, a method for inter-band calibration validation, using Antarctic site, has been developed and tested. The method relies on the directional hemispheric reflectance found in ASTER data base. In order to consider that the spectral shape of the directional directional reflectance is the same as the directional hemispheric one, wavelengths have to be limited to the spectral range below 0.9 µm. Thus this method cannot perform the inter-band calibration for the whole set of spectral bands of MSI but only from B1 to B8A. Results for B9 seem also correct although the central wavelength is a little bit beyond 0.9 µm. Given a clear day acquisition on DomeC site, a first set of computations of Top Of Atmosphere (TOA) reflectances for MSI spectral bands is performed using the three ASTER reflectances corresponding respectively to small, medium and coarse grain size for snow. The spectral reflectances are normalized by the B2 value. The comparison of the three normalized TOA reflectances to the actual one given by MSI enables to select the right snow grain size. Then the second step is the atmospheric parameters adjustment. Water content is assessed thanks to B9 band centered at 0.945 µm and ozone is assessed thanks to mainly B3 band centered at 0.56 µm. For a clear day, the aerosol optical thickness is weak and thus the TOA reflectance is not very sensitive to the more or less low abundance of continental aerosols. The ratio of normalized reflectance given by MSI to the normalized reflectance given by the computation is assessed for each spectral band between B1 and B9 and is compared to the inter-band calibration validations performed with other methods. Dans le cadre du suivi en orbite du capteur MSI de Sentinel 2, une méthode de validation de l'étalonnage inter-bande a été développée et testée. La méthode s'appuie sur la réflectance hémisphérique - directionnelle que l'on trouve dans la base de données ASTER. Pour pouvoir ...