The intriguing behavior of Bossons Glacier

4 to 6 months, starting in spring 2022

During the frequent field campaigns in the Mont Blanc area, we observed an intriguing thickening/advance of Bossons Glacier near the “Gîte à Balmat” rock outcrop during 2021 (see picture below). Moreover, the snout of this glacier going to the Taconnaz drainage basin has been advancing over the las years, which is very unusual in the Alps.

Bossons Glacier surface is very crevassed, and it is not possible to monitor it with classical field techniques. However, the glacier elevation and velocity changes can be reconstructed with remote sensing.

Figure 1 : picture of Bossons Glacier upstream of the “Gïte à Balmat” outcrop. Note that the glacier seems to thicken and overflow the rocks.

For this internship, we propose to investigate a series of high-resolution stereo images from Pléiades/Airbus that were acquired within the last ten years in the Mont-Blanc area. On average, two to three stereo images are acquired every year, with an increase in the acquisition rate in 2020-2021 (12 images). From these stereo images, it is possible to generate digital elevation models (DEMs) at a resolution of 2m, with a precision of about 50 cm (Berthier and others, 2014). From pair of sequential images, it is also possible to generate displacement fields, if the images are acquired with a suitable time separation (Millan and others, 2019).

The objectives of the internship are :
1- Building a time series of elevation and velocity for Bossons Glaciers for the period 2012-2020, in order to quantify the trend of elevation and velocity changes.
2- Adding the data from 2020-2021 to this series to investigate whether they are unusual within the multi-annual trend.
3- Investigating the glaciological processes responsible for such a change (increase of sliding…)

We encourage candidates with a strong interest in cryospheric sciences and remote sensing to apply. The candidate needs to be proficient in programming (Python preferably). A background in quantitative fluid dynamics is welcome.

References :
Berthier E and others (2014) Glacier topography and elevation changes derived from Pléiades sub-meter stereo images. The Cryosphere 8(6), 2275–2291. doi:10.5194/tc-8-2275-2014.
Millan R and others (2019) Mapping Surface Flow Velocity of Glaciers at Regional Scale Using a Multiple Sensors Approach. Remote Sensing 11(21), 2498. doi:10.3390/rs11212498.