Theia distribue les premiers produits neige

Nous sommes heureux d'annoncer que Theia a mis en ligne 93 produits neige faits à partir de Sentinel-2. Ces produits correspondent à 6 tuiles qui couvrent une partie des Alpes, des Pyrénées et de l'Atlas pour une période comprise entre juillet et novembre 2016. La production opérationnelle devrait débuter cet automne (c'est-à-dire au fil de l'eau), et couvrira une surface plus grande. Nous essaierons aussi d'améliorer les produits grâce aux retours des utilisateurs.

Série temporelle de produits neige pour la tuile 30TYN (Pyrénées)

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Theia releases first batch of snow products

We are pleased to announce that Theia has put online 93 Sentinel-2 snow products, corresponding to 6 tiles in the Alps, Pyrenees, and Atlas mountains between July 2016 to November 2016. 300 more products should be available next week. The operational production should start in autumn 2017 (i.e. near real time), and will cover a larger area. We will also strive to improve the products based on the users feedbacks!

Time series of available products for tile 30TYN (Pyrenees)

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MUSCATE News : 20000 + 93

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THEIA passed two new milestones in this beginning of summer :

  • The number of Sentinel-2A Level2A products just passed the 20000 milestone, with the complete collection of French oversea regions, and new sites along the Ganges, Brahmaputra and Mekong rivers. These sites where chosen by a research team from the GET laboratory in Toulouse.

Data are available from https://theia.cnes.fr

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Nouvelles de MUSCATE : 20000 + 93

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Deux évènements à signaler pour le centre de traitement MUSCATE de Theia pour ce début d'été :

Les données sont disponibles sur https://theia.cnes.fr

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Muscate News

After having written rather bad news from MUSCATE for quite a long time, I am very happy to send good ones, and I have to restrain myself not to provide news every day. :)

Here is the number of L2A products we are producing every day. The visible enhanced performance is due to several reasons :

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15 000 !

Theia's Sentinel-2 L2A counter passed the 15 000 threshold on the 26th of May. The joined image shows the zones which are available so far.

 

 

 

Recently, two more sites have been added to THEIA's list of processed sites :

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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.

MUSCATE news : release of Madagascar Sentinel-2 L2A data

After a good period with very little production incidents, our Muscate facility has had a tough period, which almost halted the production for one week. Until last week, the Muscate ground segment was running on CNES older cluster, and was just using the new cluster's bay of disks to store the input and output data. The access to the bay was made through the network and slowed the processing. Last week, we moved Muscate to the new cluster, and also moved physically one of the computers we are using : this brought us a few surprises that took more time than expected.

 

Muscate is now running on the new cluster : it has its own reserved computing nodes, and a dedicated facility for the scheduler. The result is that the processing of a L2A product with MAJA now only takes 23 minutes on average, while it used to be 50 minutes before. All the teams who did that migration, handling the development of Muscate, its exploitation, or the cluster facility, deserve acknowledgement !

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Last Sunday's snow cover map from Sentinel-2

We know that fast distribution of satellite products is critical for many applications, including the planning of your next weekend.

 

Olivier just announced that Theia is now delivering Sentinel-2 Level 2A data in near real time. This is great because today I was able to make the snow cover map of the Pyrenees on Sunday at 20-m resolution.

 

The L2A image was actually published on Tuesday afternoon so I could have posted this snow map two days ago.

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MACCS, renamed MAJA, now distributed as binary for non-commercial use

I have already mentioned that CNES teams working on MACCS cloud screening and atmospheric correction software and DLR teams working on ATCOR, decided to join their efforts to build a common software, named MAJA which stands for MACCS-ATCOR Joint Algorithm. And thankfully, a funding from ESA helps a lot this initiative.

 

The MAJA code relies on MACCS architecture which is designed to use multi-temporal criteria, but the successive MAJA versions will progressively include several features coming from ATCOR which did not exist in MACCS or were less elaborated and accurate.

 

We just released MAJA V1.0 which includes a few improvements (an enhanced mono-temporal mask coming from ATCOR has been included, as well as a modification of the estimation of water vapour). MAJA V1_0 is in fact just a little evolution compared to MACCS latest versions. MAJA V2.0 will include a directional correction (coming from CESBIO team), and a correction of cirrus clouds, that comes from DLR.  V1_0 version is now being integrated to Muscate, and it will soon run on our platform, while V2_0 should be delivered to CNES this week.

 

But the main news related to that is the fact that MAJA is now distributed as a binary code for linux Platforms RedHat and Cent OS versions 6 and 7 only. MAJA is distributed on CNES free software platform, and you will have to accept a licence and provide your email address. The licence is granted for non commercial use only. If you would like to get an extension of this licence for commercial use, please ask CNES.

MAJA tutorial page on github

MAJA was developed to process time series, if you only want to process a few images, please use SEN2COR. Given the size of Sentinel-2 images, MAJA is not meant to run on a laptop, it needs really serious computer resources, fast drives and processors, and several Gigabytes of Memory. I also have to stress that MAJA is not easy to use, and that solid knowledge in computers, linux, python might be necessary. MAJA also needs several stages of data preparation, including specific DTM generation.

Tutorial pages

A few beta-users are now testing the installation procedures. The first feedback is that the users often do not read the documentation carefully ;) . I strongly urge you to read the document provided in the package ! I have written a tutorial page on Github, and I hope you will manage to use it. In case of any problem, please do not comment here or send me an email, use the support address : maja-support@cnes.fr or add an issue to the github tutorial platform.