As part of the Copernicus program of the European Commission, the European Space Agency (ESA) developed and operated the Sentinel-2 constellation (S2A, S2B); and in cooperation with the EUMETSAT, they are operating the Sentinel-3 constellation (S3A, S3B). Both are Earth Observation optical missions, where the MultiSpectral Instruments (MSI) is carried on board Sentinel-2 mission and the Ocean and Land Colour Instrument (OLCI) and Sea Land Surface Temperature Radiometer (SLSTR) are on board Sentinel-3 mission. In the framework of the Copernicus Optical Mission Performance Cluster (OPT-MPC), we use the Database for Imaging Multispectral Instruments and Tools for Radiometric Inter-comparison (DIMITRI) to perform the radiometry intercomparison of the Level-1 products. The aims of this presentation are 1) to assess the quality of the data product; 2) to monitor the temporal evolution of the radiometry of the instruments MSI, OLCI and SLSTR for both unites A and B.The results of the intercomparison show a good stability of the sensors, although SLSTR-A & B show slight positive trend. MSI and SLST pairs A & B show good agreement better than 1% while OLCI constellation displays slight discrepancy up to 2-3%. While MSI-A, MSI-B, OLCI-B gain coefficients are within the missions’ requirements, OLCI-A, SLSTR-A and SLSTR-B ones are slightly higher of the mission requirements.

Continuous evaluation and ongoing validation the accuracy of active fire products derived from spaceborne instruments is of prime importance for ensuring continuity of measurements, as well as the quality of the resulting science. In this work, we present methods that are currently being setup to continuously evaluate the active fire products obtained by the SLSTR instruments aboard Sentinel-3A and Sentinel-3B, both by direct comparisons with MODIS Terra measurements, and indirect comparisons between S3A and S3B. We show that there is currently a good agreement between MODIS and SLSTR Fire Radiative Power (FRP) data, as well as between the FRP detected by S3A and S3B. We propose an indirect method to detect instrument anomalies in the absence of a "reference" sensor for simultaneous nadir acquisitions, building on the fact that S3A and S3B have the same SLSTR instrument specifications and the same local time at descending node. These results indicate that Sentinel-3 SLSTR can ensure the continuity of remote sensing observations of fire activity after the demise of MODIS.

The Copernicus Sentinel-2 Global Reference Image (GRI) was originally designed with the main goal of being used by the Ground Segment Level-1 processor to geometrically refine the Sentinel-2 data. The usage of the GRI has enabled a real improvement of the Sentinel-2 data geometric performance. Indeed, both absolute geolocation and relative (multi-temporal) performances have significantly improved and meet the requirements.It is expected that the use of the GRI could be then beneficial to other missions than Sentinel-2. In this framework and driven by user’s needs, ESA decided to freely give access to the scientific community to the entire GRI. Moreover, in order to facilitate the use of the GRI, a set of Level-1C images and a database of Ground Control Points (Level-1B and Level-1C geometries) have been derived from the Level-1B Sentinel-2 GRI. This paper recalls the characteristics of this Calibration/Validation GRI databases as well as the validations performed.

The Copernicus Sentinel-2 satellite mission, with its Sentinel-2A and Sentinel-2B units, offers since several years now a massive quantitative and qualitative resource for the Earth Observation community. Since the launch of Sentinel-2A in 2015, and Sentinel-2B in 2017, many lessons have been learnt leading to continuous improvements of the radiometric and the geometric performances. However, the current archive is composed of heterogenous processing baselines with inconsistent product formats and uneven data quality, which limits its use for multi-temporal monitoring applications.To overcome this limitation, the Copernicus program has undertaken a complete reprocessing with the latest processing baseline (05.00). It concerns the L1C (Top-Of-Atmosphere reflectance) and L2A (Surface Reflectance) products. This paper recalls the features of Collection-1 products and gives an overview of the first validation results.

The Sentinel-2 mission is a key element of the Copernicus Earth monitoring program of the European Union. The mission is currently composed of two satellites and provides a continuous observation of land and coastal areas at high spatial resolution and with a revisit time of 5 days at the equator. The geometric uncertainty of the Sentinel-2 product is a critical contributor to the performance of the mission. We present the approach used to calibrate the geometric performance of Sentinel-2 data and latest activities, especially related to the co-registration with the Global Reference Image (GRI). Generation of the GRI, coregistration algorithm, called geometric refinement, and preliminary results are presented.

The domain adaptation of satellite images has recently gained increasing attention to overcome the limited generalization abilities of machine learning models when segmenting large-scale satellite images. Most of the existing approaches seek for adapting the model from one domain to another. However, such single-source and single-target setting prevents the methods from being scalable solutions since, nowadays, multiple sources and target domains having different data distributions are usually available. Besides, the continuous proliferation of satellite images necessitates the classifiers to adapt to continuously increasing data. We propose a novel approach, coined DAugNet, for unsupervised, multisource, multitarget, and life-long domain adaptation of satellite images. It consists of a classifier and a data augmentor. The data augmentor, which is a shallow network, is able to perform style transfer between multiple satellite images in an unsupervised manner, even when new data are added over time. In each training iteration, it provides the classifier with diversified data, which makes the classifier robust to large data distribution difference between the domains. Our extensive experiments prove that DAugNet significantly better generalizes to new geographic locations than the existing approaches.

Sentinel-2 is an Earth Observation optical mission developed and operated by the European Space Agency (ESA) in the frame of the Copernicus program of the European Commission. The mission consists on a MultiSpectral Instruments (MSI) on board a constellation of two satellites flying on the same orbit but phased at 180°: Sentinel-2A launched in June 2015 and Sentinel-2B launched in March 2017. It covers the Earth's land surfaces and inland and coastal waters every five days at the equator under the same viewing conditions with high spatial resolution and wide field of view. Accurate radiometric calibration is key to the success of the mission; therefore, in-orbit calibration and validation activities are conducted within the Sentinel-2 Mission Performance Centre (MPC), including a consortium of Expert Support Laboratories (ESL). The Database of Imaging Multispectral Instrument and Tool for Radiometric Intercomparison (DIMITRI) is used to perform the vicarious validation of Level-l products delivered to users. The aims of this validation are 1) to assess the quality of the data product at Level-1, 2) to monitor the evolution of the radiometry of both instruments and 3) to ensure that the products meet the mission requirement accuracy. Three vicarious methods are used, such as Rayleigh scattering, Desert Pseudo- Invariant Calibration Sites (PICS) and Sensor-to-Sensor intercalibration methods. Although the results indicate good stability and performance of both sensors MSI-A/B, a slight discrepancy between them of ~1 % over desert sites could be observed. Slight decrease of band B8A (865 nm) signal over Algeria-3 site has been detected since April 2017. This effect seems to be related to the impact of human and industry activities near the area. Radiometric performances and image quality of Sentinel-2 MSI-A/B level-1C products appear stable and meet the mission requirements.

As part of the Copernicus programme of the European Commission (EC), the European Space Agency (ESA) operates the Sentinel-2 mission that acquires high spatial resolution optical imagery. The consistency of the image time series is ensured by some specific performance requirements such as multi-temporal spatial registration and radiometric stability, routinely monitored by the Sentinel-2 Mission Performance Centre (S2MPC). The products also provide a rich set of metadata and auxiliary data to support high-level processing activities. This presentation provides a description of the main level-1 products calibration and validation activities, performed by the S2MPC including several Expert Support Laboratories (ESL). Measured performances and analysed results show the good quality of the mission products both in terms of radiometry and geometry. The current performances for Sentinel-2A and Sentinel-2B are compared to mission product quality requirements.