Our first L2A images obtained with Sentinel-2B (and Sentinel-2A)

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The Sentinel-2B satellite was launched in March 2017, and joined his twin brother Sentinel-2A, which was orbiting since June 2015. Both satellites are now succeeding each other above our heads every 5 days. Sentinel-2 system mission is to monitor the evolution of the landscape and especially vegetation, with an observation every fifth day.

 

Very quickly, ESA managed to obtain Sentinel-2B observations over Europe very steadily, which is quite an achievement : congratulations to ESA ! CNES was greatly involved in assessing the image quality and in calibrating the sensor and has its own L1C processor (level 1C provides images registered to maps, expressed in reflectance at the top of Atmosphere).

 

By merging the time series take by Sentinel-2B and Sentinel 2A above a few sites, we managed to get dense time series of images over a few sites. To monitor a landscape, it is necessary to detect the clouds and their shadows, and to correct the variations of atmosphere transparency. This is the job of MAJA processor, which is developed jointly by CNES, CESBIO and DLR. Camille Desjardins, from CNES made it run over one of the sites..

 

So, here is the time series we obtained over a zone in Provence, France. The detected clouds are circled in green. If one ignores the clouds, which are well detected, the animation shows the slow evolution of the landscape as spring arrives. It is not possible to see a difference between the images provided by Sentinel-2B, and Sentinel-2A, which is in fact the aim of the Sentinel-2 mission. All the users will soon have access to high quality time series, with frequent observations, every five days in the absence of clouds !

 

The Muscate production center, at CNES, already distributes level 2A products  provided by MAJA software above selected regions, from Sentinel-2A data. As soon as Sentinel-2B is declared operational, its images will also be integrated in the processing.

Posted under: Corrections (geometry, atmosphere, clouds), In English, Sentinel-2, THEIA

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