1. A METHOD FOR MONOTORING GLACIER MASS BALANCE USING REMOTE SENSING IN THE FRENCH ALPS : COMPARISON WITH GROUND MEASUREMENTS (1985-2003) Jean-Pierre DEDIEU, Antoine RABATEL, Christian VINCENT, Alvaro SORUCO Laboratoire de Glaciologie et de Géophysique de l’Environnement CNRS - Grenoble, France. http://www.lgge.obs.ujf-grenoble.fr 8th Circumpolar Symposium on Remote Sensing of Polar Environments - June 8 -12, 2004 Chamonix, France

2. Glaciers Monitoring from Space Input : Additions of trends towards improvement in : Spatial and spectral resolution * Spatial and spectral resolution Frequency of repeat coverage * Frequency of repeat coverage Radiometric calibration * Radiometric calibration * Geometric fidelity Stereo capabilities * Stereo capabilities Output : National and International projects 8th Circumpolar Symposium on Remote Sensing of Polar Environments - June 8 -12, 2004 Chamonix, France

3. GLIMS : Global Land Ice Measurements from Space (http://www.glims.org) World glaciers database (ASTER satellite images)

4. Glacier Inventory at regional scale (Optical satellite images) Mer de Glace 26.09.2000 © Spot Image 8th Circumpolar Symposium on Remote Sensing of Polar Environments - June 8 -12, 2004 Chamonix, France © Landsat ETM7 – 30.07.2001 Géant Leschaux Talèfre Chamonix

5. Swiss Glacier Inventory (http://www.geo.unizh.ch) Landsat satellite images Evolution 1973-2000 (by Fanck PAUL, Andreas KAAB & al.) Mischabel mountain range Aletsch glacier region 8th Circumpolar Symposium on Remote Sensing of Polar Environments - June 8 -12, 2004 Chamonix, France

6. Objective : Glacier net mass balance Ablation area Accumulation area Photo : M. Caplain E Equilibrium line Mass balance = Accumulation + Ablation Expressed in meter water equivalent MB<0 MB>0 MB=0 Martin Gerbaux

7. St.Sorlin Glacier, 28-09-1986 (© Louis Reynaud) St.Sorlin Glacier, 05-10-1986 (© Spot-Image) annual Mass Balance derived from ELA by where db/dz = 0.78 m w.e./100 m (1985-2003) FOCUS: Equilibrium Line Altitude variations

8. Remote Sensing database French Glaciers Observatory Service (LGGE-OSUG, Grenoble) ARGENTIERE N 45°87/ E 6°90 West, 19 km 2 GEBROULAZ N 45°19/ E 6°40 North, 3.2 km 2 St. SORLIN N45°10/ E 6°10 North-East, 3 km 2 1985-2003 1. Satellite data : 1985-2003

9. Remote Sensing processing (optical and SAR data) SPOT-Image 26/08/2000 © SPOT-Image 26/08/2000 © Radarsat 26/10/1996 Raw Image D.E.M. - Geometric and radiometric corrections, ratios thresholds ( PCI inc. ) - annual ELA digitized measurement + 8th Circumpolar Symposium on Remote Sensing of Polar Environments - June 8 -12, 2004 Chamonix, France

10. 2. Ground data : 2. Ground data : direct measurements (stakes) Regression line = ELA, d(b)/d(z) 8th Circumpolar Symposium on Remote Sensing of Polar Environments - June 8 -12, 2004 Chamonix, France

12. 2. db/dz variation 1994-2002: 0,78 m water equivalent Mean Value St.Sorlin/Gébroulaz/Argentière : 0,78 m water equivalent - - 8th Circumpolar Symposium on Remote Sensing of Polar Environments - June 8 -12, 2004 Chamonix, France

13. 3. ELAs and specific net balance comparison (1994-2002): a. Field measurements (stakes)b. Field versus Remote Sensing 8th Circumpolar Symposium on Remote Sensing of Polar Environments - June 8 -12, 2004 Chamonix, France

14. 4. Comparison of cumulative specific net balance between reconstructed and direct measurements b(t) = ( ELA eq – ELA i ) * db/dz, where ELA eq = 1/n ΣELA i - * db/dz SPOT-Image 1986 © SPOT-Image 1986 4.1. Methodology: Gebroulaz glacier (1986-2003) 8th Circumpolar Symposium on Remote Sensing of Polar Environments - June 8 -12, 2004 Chamonix, France

15. 4.2. Preliminary results: Gebroulaz glacier (1986-2003) a. Surface mass balance  (t) at ELA area b. Cumulative specific mass balance b(t)

16. 4.3. Meteorological corrections and final results (1994-2002) a. Raw remoted b(t) before correction b. after Cumulated Positive Degree-Day correction (Meteo-France data)

17. 8th Circumpolar Symposium on Remote Sensing of Polar Environments - June 8 -12, 2004 Chamonix, France Limitations : The extreme summer 2003 and its effects on alpine glaciers Glacier b(t) m we 2002-2003 ELA m asl Argentière (19 km 2, N)- 2.103200 St. Sorlin (3 km 2, NE)- 2.803400 Gebroulaz (3 km 2, N)- 1.653220 Sarennes (0.5 km 2, S)- 3.153400 © Landsat TM5 26/09/1985 © ASTER 12/08/2003 Sarennes Glacier (Cemagref, since 1949) Ice Snow Rocks

18. Conclusions and outlook Mass balance reconstruction results are validated by direct ground measurements on : 2 glaciers + 8 cycles, 1 glacier + 17 cycles to study deeply ELAs yearly maps can be produced by Remote Sensing at the mountain range scale (gradient) Method of interest for climate change impact 8th Circumpolar Symposium on Remote Sensing of Polar Environments - June 8 -12, 2004 Chamonix, France

19. St. Sorlin Glacier, 1987 Thanks for your attention...