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Snow drills : snowpack investigations at local scale
Sophie Schiavone, Eric Bernard, Florian Tolle, Alexander Prokop, Jean-Michel Friedt, Madeleine Griselin, Daniel Joly
To cite this version:
Sophie Schiavone, Eric Bernard, Florian Tolle, Alexander Prokop, Jean-Michel Friedt, et al.. Snow drills : snowpack investigations at local scale: Contribution to the analysis of the Austre Lovénbreen hydro-glaciological dynamics. Taking the next step in Svalbard snow research, SSF workshop, Sep 2015, Sosnowiec, Poland. 2015. �hal-01670133�
6. Discussion and future work
Contribution to the analysis of the Austre Lovénbreen hydro-glaciological dynamics
Sophie SCHIAVONE1, Eric BERNARD1, Florian TOLLE1, Alexander PROKOP2, Jean-Michel FRIEDT3, Madeleine GRISELIN1, Daniel JOLY1
Snow drills : snowpack investigations at local scale
surface : 4,6 km²
altitude : between small alpine type coordinates : 78,8°N - 12,2°E Austre Lovénbreen
1. ThéMA - UMR 6049 - CNRS, Université de Franche-Comté, Besançon, France 2. BOKU - University of Natural Resources and Life Sciences, Vienna, Austria 3. FEMTO-ST - UMR 6174 - CNRS, Université de Franche-Comté, Besançon, France
1. Introduction
Glaciological dynamics are directly impacted by climate change, especially in the Arctic. Arctic glaciers are reliable indicators of these ongoing changes. In that context, snowpack has a crucial role which is interesting to study for a better understanding of the interacting processes in the hydrosystem.
Today, most of the studies on Arctic glaciers snowpack are performed using global scale datasets (satellite images, airbone data...). However, monitoring at local scale is necessary to analyze, understand and validate artic glaciers dynamics.
Snow drills are a valuable approach for snowpack monitoring and water content evaluation. It produces more accurate results than remote sensing methods and is easier to implement than snow profiles.
2. Objectives
The main objective of snow drills in the Austre Lovénbreen is to understand the link between snow cover processes and glaciological dynamics. These results should also be linked with liquid water runoff. Investigating the snow cover throughout the years, combined with other monitoring setup (temperature recordings, cameras, GPR...), allows to figure out which factors drive the snow cover properties and then the glacier mass balance.
3. Study site
Austre Lovénbreen is a small polythermal glacier typical from the Brøgger peninsula.
Geomorphological reasons led to the historical choice of the site (research here by J.
Corbel and his team in the 60s). It is the only drainage basin of the area where all runoffs are not braided but forced by a limestone rockband which allows a precise monitoring at the outflow.
The Austre Lovénbreen has been systematically instrumented and monitored since 2007 thanks to a succession of research programs (Sensor-Flows, Cryo-Sensors and PRISM)
4. Drilling method & data processing
100 200 300 400 500 600 700 800 900 1000 1100 1200 1300 1400 1500 1600 1700 1800 1900 2000 snow weq (mm)
1-100 101-200 201-300 301-400 401-500 501-600 601-700 701-800 801-900 901-1000 1001-1100 1101-1200 1201-1300 1301-1400 1401-1500 1501-1600 1601-1700 1701-1800 1801-1900 1901-2000 snow weq
(mm)
2008 2009 2010 2011
2012 2013 2014
drilling points glacier contour
In situ weighing of the extracted snow columns is then processed (c) and density and water equivalence (weq mm) are calculated.
Drills are made through the entire snowpack until the firn layer is reached. The campaign is made before the melting season (end of april) to minimize the risk of liquid water in the snowpack.
There are 36 sampling points homogeneously distributed on the glacier (b).
(a)
Height of the snowpack is validated using an avalanche probe (d). Several measurements are made all around the sample point to assess the quality of the measure and avoid mistakes (crevasse, hole, bédière, etc...)
(c) (d)
5. Results
(b)
(e) snow water-equivalence (mm) interpolated using IDW from snow drills data 2008-2014
Geomatic processing allows to highlight factors impacting nival dynamics and to spatialize snow properties (height, snow water-equivalence,etc). (e)
The left bank of the glacier tongue behave differently than the other side where rates are lower.
Most of the variability in snowcover is observed in altitude. (f)
Cirques seem to host an important amount of water supply especially western ones even during bad years.
Austre Lovénbreen has shown an important spatio-temporal variability in water- equivalence of the snowpack since 2008. 2011 and 2013 displayed a remarkably shallow snowcover contrary to 2012.
The spatial variability is more or less noticeable from one year to another. The snow weq standard deviation is a good indicator of these variations (as in 2014 where it was low).
(f) Interannual variability of snow water-equivalence regarding the elevation
From isolated measures to spatial generalization :
The representation of geographical data is then done using a Geographic Information System (GIS).
According to measurements, the snowpack is characterized by its height and water- equivalence. This data is spatialized using Interpolation by Inverse Distance Weighting (IDW) which has been tested and validated during field campaigns.
The snow drills method and geomatic treatments are designed to help understand snowpack behavior at a local scale. Runoffs and glacier dynamics (mass balance, etc...) depend greatly on annual snowpack conditions. Austre Lovénbreen snowpack shows important discrepancies throughout time and space. After trying to measure
snowpack with Ground Penetrating Radar (GPR), snow drills appear to be the best way to have a precise and yearly reproducible measure of snowcover properties.
It seems to be important to link the impact of nivologic dynamics to glaciological ones through new or changing processes like avalanches, rain or snow events.
References : BERNARD E., TOLLE F., FRIEDT J.M., MARLIN Ch. et GRISELIN M., 2013 : How short warm events disrupt snowcover dynamics : Example of a polar basin - Spitsberg 79°N, Proceedings of ISSW (International Snow Science Workshop), Grenoble, France, pp. 1226-1231, 6p
BERNARD E, FRIEDT J.M., TOLLE F., GRISELIN M., LAFFLY D. et MARLIN Ch., 2013 : Seasonal snow and ice dynamics monitoring using ground based high resolution photography (Austre Lovénbreen, Svalbard, 79°N), ISPRS Journal of Photogrammetry and Remote Sensing, n°75, pp. 92-100
Drill PICO (Polar Ice Coring Office)(a)
