Theia just published the first Venµs images today, including a beautiful view of the Pyrenees. Once you have dezipped/untared/unzipped the files you can make a true color composite using the command:gdal_translate -b 7 -b 4 -b 3 -scale 0 300 0 255 -ot byte VE_VM01_VSC_PDTIMG_L1VALD_ES_LTERA_20180419.DBL.TIF myColorCompo.tifI tend to focus on the snow so I stretched the colors between reflectances 0-1000 instead of 0-300:gdal_translate -b 7 -b 4 -b 3 -scale 0 1000 0 255 -ot byte VE_VM01_VSC_PDTIMG_L1VALD_ES_LTERA_20180419.DBL.TIF mySnowColorCompo.tifFirst, I was a bit puzzled by the orange shade in the northern part of the image. We inspected carefully the image with Olivier because at this stage radiometric calibration issues are still possible..

Baqueira ski resort (Tuc Deth Dossau area, Beret) on 2018 Apr 19 by Venus
However the same color is also visible in yesterday's Sentinel-2B image of the western Pyrenees.
Formigal ski resort on 2018 Apr 19 by Sentinel-2B
Also, webcams all across the Pyrenees show the same orange snow, for example this picture shows the same area as the Venµs image above:
Baqueira ski resort (Tuc Deth Dossau area, Beret) on 2018 Apr 20 (webcam picture from https://www.baqueira.es/)
It looks like Saharan dust but I don't know when it happened! In the previous Venus image (2 days before, on April 17) the snow looks more "white" but some orange shades are still visible.
Baqueira ski resort (Beret area) by Venus
I called the Arcalis ski resort to figure out and a nice woman told me that this brown powder came two weeks ago while it was raining/snowing. I should stop looking at satellite images and go more often to the field..


A month later, the dust layer resurfaced:

6 thoughts on “Venµs captured the orange snow in the Pyrenees

  1. Dear Simon, even our cars were covered by orange dust in Pau and in the Western Pyrennees. Yes you need to leave Toulouse for having a look to the real Pyrennean life. Cheers, Bernard

  2. In this case, the orange color came from a new deposit. But in late season, it could have been an old one coming back to the surface because of the melt. Even though the aspect would probably be less uniform in this case as the snow has not the same depth and the same melt rate everywhere.

  3. Here is the picture I took before crossing the Aragnouet Bielsa tunnel on April 21st. Patches of orange and white snow were easily visible. https://photos.app.goo.gl/ASqsYshG3kZZ6xgK6I took almost the same photograph 6 days later when coming back. A lot of melt had occurred. Presence of orange snow was less obvioushttps://photos.app.goo.gl/TXoU4KcSmL8F7WFs6

Laisser un commentaire

Votre adresse de messagerie ne sera pas publiée. Les champs obligatoires sont indiqués avec *