You must have seen, in the press or social networks, images like these ones, showing yellow skies ( Loup de Bretagne said "Blade Runner skies"). Such a coloured sky was seen in the west of France, then later in England, and further East in the next days.
The Copernicus Atmosphere Monitoring Service, which keeps track of aerosols has also monitored these aerosols and tracked their provenance : is due to the combined presence of dust, ash from forest fires in Spain and Portugal, and humidity brought by the Ophelia cyclone. The IASI sensor on-board METOP satellites has also monitored the gases absorption due those wildfires.
So our question is: how such an event is handled by atmospheric correction software ?
Post préparé par Marine Bouchet pour le blog Kalideos Alpes (version originale)
Les séries temporelles d'images optiques des satellites Sentinel-2 permettent un suivi de la surface enneigée à une résolution spatiale de 20 m tous les 5 jours (en l’absence de nuages). Le CNES et le CESBIO développent, depuis 2015, une chaîne Let It Snow (LIS) pour extraire de façon robuste les masques de neige associés, distribués sur la plateforme Theia.
Update : MUSCATE is back on track for the real time production, thanks to PEPS return to nominal production, and a better stability of our platform.
Some of you will have probably noticed that Theia production of Sentinel-2 L2A data is quite slow these days, and is not producing all the data it should in real time. The reason is we started to implement a correction to solve the performance issues we had. This correction was tested and qualified during several days, in operational conditions, but when put in production, turned out to be unstable, due to occasional slowness in CNES cluster which did not happen when the correction was in tests. Moreover, our source of Sentinel2 data, PEPS, was experiencing some difficulties, providing a much reduced number of images.
We are waiting for a correction of the correction (the cause has been found and corrected but needs to be tested), The new version should be installed in less than 2.3 days, as Dilbert (dilbert.com) says. And all the team is very sorry for the delays and the inconvenience it is causing.
Non, non, la fréquentation de ce blog n'est pas en baisse au point qu'il nous faille attirer une nouvelle clientèle pour compenser une perte de revenus financiers issus de la publicité. (La fréquentation augmente régulièrement d'ailleurs, mais les revenus financiers sont nuls...)
Le satellite Venµs nous a vraiment montré la lune, et ce n'est pas seulement pour proposer une belle image et un titre accrocheur sur le blog du CESBIO. Nos collègues israéliens de MBT se sont d'ailleurs donné beaucoup de peine pour l'obtenir, car il faut une très bonne précision de pointage pour l'observer : la lune est loin !
Our MUSCATE ground segment just passed a new milestone, with 40 000 L2A products processed with MAJA ! Last week was a bit difficult, with a new repetition of the Friday Night Bug (on Saturday morning this time), followed by a "NFS" issue on CNES computing center that blocked production during two days. We are sorry for those of you waiting for the data in near real time. The production has resumed last Friday. These days, our production includes the near real time production and the processing of data acquired in 2016 over Spain, Italy, Switzerland and Netherlands. Some parts are already available, Burgos in Spain for instance, the others should come soon.
The version 2.4 of MUSCATE is nearly ready, but a final bug, noticed during the qualification tests remains to be corrected. As soon as it is installed and checked, this version will bring several improvements :
I just came back from Valencia, where I attended the fifth edition of the Recent Advances in Quantitative Remote Sensing Symposium. It is one of my favourites, thanks to an amazing team of organizers led by Jose Sobrino. It is a unique symposium, because it has only one session where you can even see opticians listen to radarists, or passive microwaves experts share ideas with active microwave experts ! Every three years, it is a way to gather quickly a good sense of the advances in each domain of remote sensing, over lands mainly. Next RAQRS will happen in 2020 in Valencia, and no doubt I'll be there, and not only for the delicious coffee breaks or for the giant paella.
Of course, my talk, available here or visible below, was about Sentinel-2 L2A products, including cloud detection and atmospheric correction. This time, I focused on product validation and provided a lot of validation results obtained by our little team at CNES and CESBIO, with special thanks to Camille Desjardins (CNES) and Bastien Rouquié (CESBIO) and Magdalena Main-Knorn (DLR). I also provided a comparison of MAJA and Sen2cor for various criteria that all show the benefits of using multi-temporal information, as done in MAJA. Despite all that, and although these results were perfectly known by ESA, ESA decided to stick with Sen2cor in their production, supposed to be global next year. The slides explain how this decision was made.
Anyway, as you probably know, you can access MAJA products from Theia, or you may also download MAJA's executable (if you have a powerful linux computer).
Yesterday, MUSCATE facility at CNES produced 1141 Sentinel-2 L2A products in a day, while the previous record was 762. A few glitches had reduced the production on the previous days, and yesterday allowed us to catch up the back log. At the same time we have started producing data acquired in 2016 for several zones outside Europe and Africa. The total number of L2A products in MUSCATE now amounts to 33071. Congrats and thanks to the development and exploitation teams !
Hier, le centre de traitement MUSCATE au CNES a traité 1141 produits de niveau 2A de Sentinel-2, alors que le record précédent était 762. Quelques petits soucis avaient retardé la production ces derniers jours, et c'est hier que nous avons rattrapé le retard, et en même temps lancé la production des données acquises en 2016 sur un grand nombre de zones hors Europe et Afrique. Le nombre total de produits de nievau 2A atteint maintenant 33871. Félicitations et un grand merci aux équipes de développement et d'exploitation !
Done ! All Sentinel-2 data acquired above Italy, Switzerland and Austrian Alps, and processed at level 2A, are now available on Theia website! The data format is described here. We would be very thankful if users in Italy or Switzerland could help us spread the news among remote sensing users in both countries.
The level 2A product provides surface reflectances with a good cloud and shadows mask. The processing is done at CNES, within MUSCATE facility, using the MAJA software, developed by CNES, CESBIO and DLR. The production started with data acquired in December 2016, and will go on in near real time.