India water crisis: Sentinel-1 detects surface water, ForEarth app restitutes and shares water stresses

In the framework of an open call Science4society funded by ESA, researchers at CESBIO have implemented a surface water detection algorithm from radar data Sentinel-1 on a cloud computing system. An API developed by Geomatys and JeoBrowser, two IT companies in France, is used to send the resulting surface water masks to a smartphone App named ForEarth, which display the surface water fluctuation in time for Indian regions.

The beta version is available on PlayStore and displays statistics and water masks for the Hyderabad region, Telangana, India.

The Hyderabad area has been processed. rest of India will be processed soon

Select your area of Interest

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Major changes for Venµs data processing

We are about to implement a major change in the ground segment of VENµS. Until now, L1C and L2A products were produced in the Venµs Image Processing (VIP) center, and imported into THEIA catalog. Next week, this will be changed.


L1C products will still be produced by the VIP, but the L2A will be generated by MUSCATE center within Theia. Moreover, it will soon be possible to generate L3A products which are bi-weekly composites of cloud free surface reflectances. And the cherry on the cake, all these products will be delivered at 5m resolution, while the L2A products were only available at 10m resolution.


This change comes with some drawbacks for users : the formats will slightly change to keep homogeneity between all the products distributed by MUSCATE.

  • the metadata format is different, the keywords have changed.
  • the images are still provided with TIFF format, but there is now one file per band. For L2A only, The scaling factor has changed, it is now 10000, as for Sentinel-2.
  • the L2A resolution is now 5m !
  • the grid used corresponds to that of Sentinel-2, you only have to account for the upper left origin of each site to obtain the registration of the images. No reprojection and no resampling is necessary.


These changes will be first applied to the real time processing, but the whole archive will be reprocessed later on.


A description of the new formats is provided in the following references :


During a few days, both versions will coexist in Theia distribution server. The new products contain the "_XS_" string in their filenames, so they are easy to recognise.


MAJA and LIS selected for the next Pan European high resolution snow and ice monitoring service

The European Environment Agency (EEA) has selected a consortium led by Magellium to implement the next Pan European high resolution snow and ice monitoring of the Copernicus Land Monitoring Service.

EEA 34 countries and corresponding Sentinel-2 tiles

This future service aims to monitor three variables at 20 m resolution over the tiles displayed above:

  1. Fractional Snow Cover (FSC)
  2. Permanent Snow Line (PSL)
  3. River and Lake Ice (RLI)

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Le catalogue Theia/Muscate compte maintenant 200 000 produits Sentinel2 de niveau 2 et 3


Le centre de production THEIA MUSCATE a franchi une nouvelle étape dans la nuit du 26 au 27 juin 2019. Il y a maintenant 200 000 produits Sentinel-2 N2A et N3A dans notre catalogue. Il a fallu deux ans et demi pour passer le cap des 100 000 produits en août dernier , mais nous avons doublé ce nombre en moins d'un an. C'est la preuve que notre système de production est maintenant mature et robuste, même s'il demande encore beaucoup de travail de la part de l'équipe d'exploitation, que nous remercions beaucoup !


Mais comme vous pouvez le voir ci-dessous, si le nombre de produits Sentinel-2 est le plus élevé, et aussi le plus téléchargé, le nombre de types de produits que nous fournissons aux utilisateurs augmente régulièrement. Nous vous parlerons bientôt du produit " qualité de l'eau" qui vient d'apparaître à la fin de la liste.


200 000 Sentinel-2 L2A and L3A products in Theia catalog


THEIA MUSCATE production center passed a new milestone during the night of the 26th to 27th of June 2019. There are now 200 000 Sentinel-2 L2A and L3A products in our catalog generated with MAJA. It had taken two years and half to pass the 100000 products milestone last august, but it took less than a year to double that number. This is a proof that our production system is now mature and robust, even if it still requires a lot of work from the exploitation team, which we thank a lot for their hard work !


But as you can see below, if the  number of Sentinel-2 products is the highest, and also the most downloaded by far, the catalogue has grown a lot, and the number of products we provide to the users is steadily increasing. We will soon tell you about the water quality product that just appeared at the end of the list.



[VENµS] Venµs data production currently stalled

As the CNES project team was celebrating the 10 000th orbit of VENµS satellite (without me, I had another meeting at the same time :( ), the exploitation received a bug report: the production of the Venµs Image processing  had stopped.


That was not a coincidence to ruin the joy of the social event, and it was not jealousy from my side, but just the fact that somewhere in the ground segment, the orbit number was coded with 4 digits.

Update 26/06/2019-16h30

The bug has been corrected and production resumed.

Sentinel-2 captures new data centers in Iceland

In a remote sensing study published in Nature, the authors claimed that they used "101 CPU-core years of computation (..) within the Google data centres". This made me wonder what could be the carbon footprint of such a study?. I estimated that it should be 65 tonnes of carbon dioxide, but a Google engineer replied:

Google purchases enough renewable energy to offset 100% of its energy use for its offices and data centers.

In just a few years, the company has made an impressive move to renewables, true to its famous motto "don't be evil". Google is the largest corporate purchaser of renewable energy on the planet. However, it's better to save energy than to buy renewable energy, as explained by Forbes:

It is true that Google is buying all its electricity from renewable sources, but it is unlikely that all the electricity it is using comes from renewable sources. This is because solar and wind, Google’s choices for renewable sources, are both variable, while Google’s electricity demand is not. In other words, there are times and locations when Google must use electricity that comes from traditional sources, while simultaneously the electricity generated from the renewable projects funded via Google’s PPAs is curtailed and lost.

To save energy (and cost), large tech companies are moving data centers in Nordic countries like Iceland to take advantage of the "free air cooling". Moreover in Iceland the electricity production relies primarily on hydropower and geothermal heat.

Sentinel-2 images of data centers in Reykjanesskagi, Iceland

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Detecting geolocation errors in glacier outlines with Sentinel-2 snow cover duration maps

Two years ago I posted an animation of the snow cover area evolution near Zermatt, Switzerland from Sentinel-2 L2A data processed by LIS.

From this time series of snow maps I generated a snow cover duration map and
added the glacier outlines from the Randolph Glacier Inventory 5.0.

Colors: Snow cover duration between 01 Sep 2016 to 31 Aug 2017 (in days). Black line: Glacier outline from RGI.

I was satisfied by the overall good agreement between the areas with a high snow cover duration and the glacier outlines. However by looking more closely at the small isolated glacier in the eastern part I noticed a mismatch between both datasets..
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THEIA's Sentinel-2 L2A processing on Sahel is progressing


As we had announced in November, the MUSCATE production centre in Theia is gradually adding areas in the Sahel, which are shown in the image below. The data are processed from December 2016 onwards, which means that we have a large amount of data to process. So we started with the most westerly tiles, in Senegal on the UTM28 zone, then progressed from one zone to another towards the East.

Theia Sentinel-2 processing area on the Sahel


In red, the tiles available from Dec 2016 to NRT, in blue , the remaining tiles to be added.

In recent days, Theia has completed the processing of tiles in the UTM29 area, which mainly covers northern Guinea and western Mali, but also partially covers southern Mauritania and Sierra Leone and north-western Côte d'Ivoire. The treatment of the UTM 30 zone, which covers Burkina Faso and Mali, is also well advanced. The east of this area is finished, and the west is progressing well, as shown in the animation below. The UTM31 zone has also been brought into production. Feel free to take a look from time to time at the map of areas covered by MUSCATE. The blue tiles turn red as soon as we switch to run-of-river processing.


The data can be downloaded from here:


Animation in the region of the city of Mopti, Mali, with about one image per month in 2017. The displayed time series extends between two rainy seasons and covers the dry season. Many fire scars are visible during the dry season. Some shadows appear, which actually correspond to the shadows of cirrus clouds corrected by MAJA. Shadows and cirrus are marked in the products.

Le traitement des données Sentinel-2 L2A au Sahel progresse


Comme nous l'avions annoncé en Novembre, le centre de production MUSCATE de Theia rajoute progressivement des zones au Sahel, qui sont affichées sur l'image ci-dessous. Les données sont traitées à partir de décembre 2016, ce qui nous fait une grande quantité de données à traiter. Nous avons donc commencé avec les tuiles les plus à l'ouest, au Sénegal sur la zone UTM28, puis de proche en proche vers l''Est.

Zone de traitement Sentinel-2 sur le Sahel proposée à Theia. En vert foncées les tuiles qui déjà traitées par Theia, en teintes claires, les tuiles que nous ajoutons progressivement.


Depuis quelques jours, Theia a terminé le traitement des tuiles de la zone UTM29 qui

En rouge, les zones déjà disponibles en temps réel et depuis fin 2016, en bleu, les zones qui le seront bientôt.

couvre principalement le Nord de la Guinée et l'Ouest du Mali, mais aussi partiellement le sud de la Mauritanie et la Sierra Leone et le Nord Ouest de la Côte d'Ivoire. Le traitement de la zone UTM 30 qui couvre le Burkina Faso et le Mali, est lui aussi bien avancé. L'est de cette zone est terminé, et l'ouest avance bien, comme le montre l'animation ci-dessous. La zone UTM31 a elle aussi été mise en production. N'hésitez pas à jeter un coup d’œil de temps en temps à la carte des zones couvertes de MUSCATE. Les tuiles en bleu deviennent rouges dès que l'on passe au traitement au fil de l'eau.


Les données peuvent être téléchargées ici :


Animation sur la région de la ville de Mopti, au Mali, avec environ une image par mois en 2017. La série temporelle s'étend entre deux saisons des pluies et couvre la saison sèche. De nombreuses cicatrices d'incendies sont visibles pendant la saison sèche. Quelques ombres apparaissent, qui correspondent en fait aux ombres des cirrus corrigées par MAJA. Les ombres sont marquées dans les produits.