Sentinel-2 Level-1 Products Content and Format Specification
Cadau, Enrico Giuseppe1; Gascon, Ferran2; Colin, Olivier2; Lopez, Borja2
1Serco/ESA, ITALY; 2ESA, ITALY
This paper aims at presenting the GMES Sentinel-2 Level-1 products in terms of data content and format specifications. Sentinel-2 Level-1 products generation includes three main steps to generate Level-1A, Level-1B and Level-1C data. All data acquired by the MSI instrument are systematically processed up to Level-1C in the Payload Data Ground Segment (PDGS). Level-1B and Level-1C will be made available to general users. Level-1B data are radiometrically corrected radiances. The physical geometric model is refined using available ground control points and appended to the product but not applied. In consequence, the Level-1B product is mainly addressed to users experienced with ortho-rectification techniques. The Level-1C is the Orthorectified product which provides geocoded top-of-atmosphere TOA reflectance with sub-pixel multispectral and multi-date registration. Cloud and land/water masks are associated with the product. The cloud mask also provides an indication of the presence of cirrus clouds. The ground sampling distance of Level-1C products is 10 m, 20 m or 60 m, depending on the band. The image data is embedded the Level-1C product in a set of image tiles of 100x100 km each, covering altogether the user selected area, and with the desired set of spectral bands coded in JPEG2000 format. The products will be delivered in Sentinel-SAFE format. The generic SAFE format has been designed to act as a common format for archiving and conveying data within ESA Earth Observation archiving facilities. The Sentinel-SAFE format wraps a folder containing image data in a binary data format and product metadata in XML. This flexibility allows the format to be scalable enough to represent all levels of Sentinel-2 products. Level-1 products are constituted by a main folder containing: · XML main product metadata file; · XML manifest.safe file; · A Preview image of the product; · XML INSPIRE metadata file; · A set of sub-folders containing respectively: Image data files; Image metadata files; Auxiliary data; Sentinel-2 data products will follow the recommendations of Quality Assurance Framework for Earth Observation (QA4EO) agreed by the Committee on Earth Observation Satellites (CEOS, 2010). Performance traceability and radiometric and geometric quality indices will be provided with the ancillary product metadata. The Sentinel-2 datasets in their inherent quality of describing spatial data are fully entitled to comply with the directive and hence the INSPIRE Metadata directive applies in entirety to the Sentinel-2 product set.