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Copernicus Sentinel-2A Calibration and Products Validation Status

Ferran Gascon, Catherine Bouzinac, Olivier Thépaut, Mathieu Jung, Benjamin Francesconi, Jérôme Louis, Vincent Lonjou, Bruno Lafrance, Stéphane Massera, Angélique Gaudel-Vacaresse, Florie Languille, Bahjat Alhammoud (+11 others)
2017 Remote Sensing  
As part of the Copernicus programme of the European Union (EU), the European Space Agency (ESA) has developed and is currently operating the Sentinel-2 mission that is acquiring high spatial resolution optical imagery. This paper provides a description of the calibration activities and the current status of the mission products validation activities. Measured performances, from the validation activities, cover both Top-Of-Atmosphere (TOA) and Bottom-Of-Atmosphere (BOA) products. Results
more » ... d in this paper show the good quality of the mission products both in terms of radiometry and geometry and provide an overview on next mission steps related to data quality aspects. between minimizing cloud cover and ensuring suitable sun illumination. An overview of the MSI imaging payload is provided in the following section. The Sentinel-2 satellites will systematically acquire observations over land and coastal areas from −56 ° to 84 ° latitude including islands larger 100 km 2 , EU islands, all other islands less than 20 km from the coastline, the whole Mediterranean Sea, all inland water bodies and all closed seas. Over specific calibration sites, for example DOME-C in Antarctica, additional observations will be made. The two satellite units will work on opposite sides of the orbit. Sentinel-2A launch took place in June 2015 and Sentinel-2B is foreseen beginning 2017. Therefore, this paper focuses only on the performances achieved by Sentinel-2A. The availability of products with good data quality performances (both in terms of radiometry and geometry accuracies) has a paramount importance for many applications. This is indeed a key enabling factor for an easier exploitation of time-series, inter-comparison of measurements from different sensors or detection of changes in the landscape. Calibration and validation (Cal/Val) corresponds to the process of updating and validating on-board and on-ground configuration parameters and algorithms to ensure that the product data quality requirements are met. This paper provides a description of the calibration activities and the current status, one year after Sentinel-2A launch, of the mission products validation activities. Measured performances, derived from the validation activities, have been estimated for both Top-Of-Atmosphere (TOA) and Bottom-Of-Atmosphere (BOA) products (referred respectively as Level-1 and Level-2A and further described later in this paper). . Multi-Spectral Instrument Overview This section provides a brief overview of Sentinel-2 Multi-Spectral Instrument (MSI). It aims at giving to the reader the basis required to fully understand the measured performances and the Calibration and Validation (Cal/Val) approach. MSI Design The MSI instrument design has been driven by the large swath requirement together with the demanding geometrical and spectral performances of the measurements. It is based on a push-broom concept, featuring a Three-Mirror Anastigmatic (TMA) telescope feeding two focal planes spectrally separated by a dichroic filter, as shown on Figure 1 . One focal plane includes the Visible and Near-Infrared (VNIR) bands and the other one the Short-Wave Infrared (SWIR) bands. Figure 1. MSI internal configuration. On the left, full instrument view and optical path construction to the SWIR/VNIR (see §2.2) splitter and focal planes. Spectral Bands and Resolution Preprints ( | NOT PEER-REVIEWED | Posted: Overlapping area = 98 pixels @ 20m 10 bands B/H cross-detector B/H cross-band Nb pixels / detector module: 2592 (10m) or 1296 (20m -60m) Satellite track YLOS XLOS ZLOS ψX ψY Viewing direction Preprints ( | NOT PEER-REVIEWED | Posted:
doi:10.3390/rs9060584 fatcat:fglsduu6g5bjpd6nmxpspa2hfy