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As announced a few months ago, our monthly synthesis processor for Sentinel-2 data, WASP, has been integrated to THEIA's land data center processing facility at CNES, in spring 2019. We are therefore now extending the zones where we process the monthly synthesis (the so-called Level-3A products).

How to query Theia catalog to find Level 3A products over Spain

After France, the first countries that we added are Spain, Portugal, and Andorra, and now Italia.  So, we are happy to release out first high quality monthly Level-3A syntheses of surface reflectance of the whole Iberian peninsula, valid for August and September 2019. As for the standard Level-1C and Level-2A products of Sentinel2, the Level-3A product is split in tiles of 110*110 km, and is available for all Sentinel-2 spectral bands, except the atmospheric bands (B1, B9, B10). This data set can be downloaded, for free, from Theia web site, using the following request:

https://theia.cnes.fr/atdistrib/rocket/#/search?q=Spain&collection=SENTINEL2&processingLevel=LEVEL3A

If your browser language is French, please use the following link:

https://theia.cnes.fr/atdistrib/rocket/#/search?q=Espagne&collection=SENTINEL2&processingLevel=LEVEL3A

 

We also usually create a mosaic of these tiles, for visualisation purposes, using only the Red, Green and Blue spectral bands, at 20m resolution (the Theia Level-3A products are available at 10m resolution). This mosaic shows the quality of the synthesis, as usually, a monthly synthesis is plagued with artefacts, but the ones we have here are very faint.  However, the mosaic is not completely cloud free, as Sentinel2 did not manage to obtain a cloud free observation in Asturias,  but, well, people who have been there know how difficult it is even in August.

 

 

Click on the image to zoom to 20m resolution, and to compare the syntheses of the different months. Will you spot the 1000 or more differences ?

To have a detailed description of the methods behind WASP, please read the link provided below. In a few words, WASP (Weighted average Synthesis Processor) computes a weighted average of Sentinel-2 cloud free reflectances gathered over a duration of 46 days, centered on the 15 th day of each month. This processing relies on the quality of atmospheric correction and above all cloud detection obtained from MAJA L2A processor.

 

Theia's Sentinel-2 L3A monthly cloud free syntheses

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