Sentinel-2A unveils two new lakes in Borneo

The remote sensing company Planet has published images, which were captured by its fleet of nano-satellites, of Lake Bakun on the island of Borneo [1]. Planet tells us that this artificial lake is the largest lake in Southeast Asia since its flooding in 2011. Yet it is not visible on mapping web services like Bing Maps or Google Maps! It does show in OpenStreetMap at low resolution. This is due to the fact that the island of Borneo is one of the most cloudy places in the world so the usable optical remote sensing images are very rare.
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Sentinel-2A dévoile deux nouveaux lacs sur l'île de Bornéo

L'entreprise de télédétection Planet a publié des images, prises par sa flotte de nano-satellites, du Lac Bakun sur l'île de Bornéo [1]. Planet nous apprend que ce lac, formé par un barrage construit en 2011, est le plus grand lac d'Asie du sud-est. Pourtant, il n'est pas visible sur les services web de cartographie comme Bing Maps ou Google Maps ! On peut le trouver dans OpenStreetMap avec une faible résolution. Cela est dû au fait que l'île de Bornéo est un des endroits les plus nuageux au monde donc les images de télédétection optiques utilisables sont très rares.
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Écobuages dans les Pyrénées Ariégeoises vus par Sentinel-2A

Hier avec mon collègue Pascal nous sommes allés réparer le pluviomètre de notre station météo dans le Vicdessos. Outre l'absence de neige anormale à cette saison, le versant d'en face était largement calciné ce qui donnait au paysage un aspect désolant. Le feu n'était pas terminé car certains secteurs continuaient à fumer. D'après un garde de l'Office National des Forêts que nous avons croisé il s'agissait des conséquences d'un écobuage illégal [1].

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Pine Island Glacier rift

The rift of Pine Island Glacier's floating tongue is a cause of concern among glaciologists because it suggests that this part of the ice shelf is not stable and may collapse in the future. As explained in this EOS article [1]

Rifts usually form at the sides of an ice shelf where the ice is thin and subject to shearing that rips it apart. But this particular rift originated in the center of Pine Island Glacier’s ice shelf and propagated out to the margins.This implies that something weakened the center of the ice shelf. The most likely explanation is that a crevasse melted out at the bedrock level, driven by a warming ocean, according to the researchers."

Online survey: can we detect an expansion of the rift on the Sentinel-2 images only?

Sentinel-2 images of the Pine Island Glacier ice shelf rift. Each subset shows the eastern portion of the rift on a different date. Which one shows the longest rift according to you? Click on the image to vote!


The results of the survey are given in the next post.


[1] Lipuma, L. (2017), West Antarctic ice shelf breaking up from the inside out, Eos, 98, doi:10.1029/2017EO064743. Published on 04 January 2017

White Christmas in Aleppo

This is a Sentinel-2A image of Aleppo on Dec 22, showing some snow through the clouds. I do not know if this sunny interval lasted a long time, and I wonder if the inhabitants of Aleppo had wished snow for Christmas. I walked through the streets of Aleppo in July 2003 at the end of my bachelor's internship which was held mainly in Damascus and Palmyra. Aleppo is the most fascinating city that I have visited in Syria. I remember the alignments of soap, cloth and hardware stores that narrowed even more the narrow alleys of the old city. I remember the Persian carpets hanging from the balustrades of the ancient caravanserais. I remember countless smiles exchanged with people whose language I did not speak, in the souk, in the mosques, where tourists like me were welcome. I remember the kids playing soccer in front of the walls of the citadel. I wonder if kids played snowballs on December 22, 2016 in Aleppo. I'm sad and I'm a little ashamed too.

Aleppo (Sentinel-2A image of 22-Dec-2016)