L'Antarctique sort à peine de sa torpeur hivernale que déjà deux évènements majeurs viennent de se produire sous l’œil de Sentinel-1.
Le 12 juillet dernier, une crevasse géante à fendu la barrière de glace Larsen C , mais il a fallu attendre que la banquise desserre son étau en septembre pour que l'iceberg A68 commence à dériver. Ce glaçon couvre une superficie de 5800 km² (les deux tiers de la Corse).
Back from a long summer break, I needed to find something else to do than just catching up with emails... Luckily, the organizers of the 2017 International Glaciology Society meeting in Boulder tweeted this animation of the Vavilov Glacier (October Revolution Island, Russian Arctic):
Zermatt is in the corner of the Sentinel-2 tile 32TLS, which is produced at level 2A by Theia. Hence I could generate the snow maps at 20 m resolution for this area (105 dates from December 2015 to October 2017).
Voir en plein écran
The rift of Pine Island glacier was captured by Sentinel-2A several times since Sentinel-2A is watching Antarctica. However I was not sure if the crack was growing by looking at the images only. Continue reading
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 
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!
 Lipuma, L. (2017), West Antarctic ice shelf breaking up from the inside out, Eos, 98, doi:10.1029/2017EO064743. Published on 04 January 2017
Sentinel-2A was launched on 23-July-2015 but the routine operations started in July 2016 after the ramp-up phase . Now with the onset of the austral summer, the first Sentinel-2A images of Antarctica are getting available (except for Dome C, which is a calibration site).
A Pléiades stereo pair has been acquired on 2016-Oct-01 just a few days after the second glacier collapse in the Aru mountains. The panchromatic band has 0.5 m resolution, which allowed us to generate a post-event digital elevation model of the area. From this digital elevation model and the Pléiades 2 m multispectral imagery, Etienne Berthier generated these stunning 3D views of the aftermath...
Preliminary estimates of the volume detached from the glaciers are 66 Mm3 (first, north one) 83 Mm3 (second, southern one).
"The most usual weather in these latitudes is a fresh wind between north west and south west with a cloudy overcast sky" - Phillip Parker King, Sailing Directions for the Coasts of Eastern and Western Patagonia (1832).
Patagonia is a beautiful place to visit but campers know that the weather is extremely variable and the sky is often cloudy. This can be a problem for glaciologists, too, since they rely on optical satellite imagery to study glacier area changes over the last decades (mainly Landsat). Clear-sky optical images can also be used to determine glacier velocity, albedo, front variations, etc.
The giant ice avalanche that occurred in Tibet on 17 July 2016 and killed 9 people  urged scientists to scrutinize every available data to understand what caused such a glacier collapse. In doing so, they witnessed in near real time the ongoing collapse of a second glacier.