=> When the summers were hot and dry during the past years, our monthly cloudfree syntheses of surface reflectances from Sentinel-2 for the month of July interested the media. It will probably not be the case in 2021, as France thankfully kept its green colour in July. Because of the cloud cover that […]
A few years only after its worst drought in 1,200 years (2011-2016), the drought returns to California. Lake Oroville is both a witness and a victim of the extreme hydro-meteorological variability in the Golden State. It provides water to « homes, farms, and industries in the San Francisco Bay area, the San Joaquin Valley and Southern […]
This post intends to answer a question about Sentinel-HR, that we have had quite often inside or outside CNES : Securing continuity in a critical timeseries requires user community foresight, Programme justification, 10 yrs Agency prep, and finances. Whilst Sentinel-HR may well be an excellent/valid idea, I’m left asking why certain Copernicus contributing missions couldn’t […]
=> Si vous travaillez avec des produits Sentinel2, vous avez probablement entendu dire que le nouveau traitement géométrique de l’ESA est actif depuis le 1er avril 2021. Ce nouveau traitement se base sur l’affinage des paramètres de prise de vue par rapport à un ensemble d’images de reference (Global Reference Image, GRI), et doit diminuer l’erreur […]
=> If you are working with Sentinel2 products, you probably heard that ESA new geometric processing is active since 1st of April 2021. This new processing, based on the geometric refinement of viewing parameters with respect to a Global Reference Image (GRI), should bring absolute location error from 11 meters (95.5% of products) to better […]
Muldrow Glacier (McKinley Glacier) is a large glacier in Denali National Park and Preserve in Alaska, USA. It is now moving 100 times faster than normal, which means that it is undergoing a « surge ». The abrupt acceleration of the glacier movement is clearly visible in the recent series of Sentinel-1 SAR backscatter images (animation below). […]
The distribution of MAJA L2A processor, as an executable software, started in april 1997, but we started counting the number of downloads only since October 2017. The cumulative number of downloads just reached 2000 on April the 2nd 2021. It is on average 1.56 downloads per day, and more than 2 downloads per work day […]
=> Here is a frequently asked question : I noticed, in such L2A product processed by MAJA, that some pixels had negative reflectances, is it normal ? No, it should not happen, but the fact it happens is not entirely surprising, I will explain it below. Unlike negative reflectances, reflectances greater than one can exist, […]
=> Voici une question que je reçois assez fréquemment : J’ai remarqué dans (tel produit L2A Sentinel-2 corrigé des effets atmosphériques par MAJA) des réflectances négatives ou égales à zéro. Est-ce normal ? Non, ce n’est pas normal, mais ce n’est pas totalement surprenant non plus. Contrairement aux réflectances négatives, qui ne devraient pas exister, […]