Evolution of Ossoue glacier, French Pyrenees: Tools and methods to generate a regional climate-proxy

Transcription

1 Evolution of Ossoue glacier, French Pyrenees: Tools and methods to generate a regional climate-proxy Renaud MARTI ab, Simon GASCOIN a, Thomas HOUET b, Dominique LAFFLY b, Pierre RENE c a CESBIO b GEODE, c Moraine renaud.marti@gmail.com CESBIO Snowminar

2 Climate change in southern Europe/Mediterranean _Hot spot of climate change (e.g. IPCC AR5, 214) _Strong impacts on water resources including snowmelt from mountain areas Case of Pyrenees mountain _higher vulnerability to climate fluctuation, particularly for the cryosphere _longest meteorological timeseries: Pic du Midi starting in 1878 (at 2862m a.s.l.). _tree-ring timeseries (e.g period, Büntgen et al., 28) Interest of glacier study : high climate sensitivity (mainly mean temperature and accumulation) 1911 : L. Gaurier 25 : P. René

3 Name Geographic location Drainage Basin Glacier type Planimetrical dimension Aspect Profile Moraines Bed rock Glacier activity Snow accumulation Ice thickness (h) in the upper zone Ossoue glacier -Vignemale massif N 8 4 W Gave de Pau Cirque glacier Length : 14m±5m Width : 4m±5m Area :,45km 2 ±.1km 2 Mainly East Longitudinal : slightly irregular (1 ) then stepped (25 ) Transversal : convex No moraine in contact to present-day glacier Farther downstream visible moraines Limestone marble/ Quartzite Mean stake displacements velocity : Upper part : 1.3m±1m.year -1 Lower part : 8m±1m.year -1 (GPS 22-26) Equilibrium line altitude (ELA) above the glacier. Direct snow and few avalanching. Mean : -3m±1 m Max.:-72m±1 m (26 GPR) Elevation (m a.s.l) Median elevation: 376 m a.s.l. Mean elevation: 346 m a.s.l. Area (Ha)

4 Regional climate-proxy generation : data collection End of LIA t Reconstruction of Ossoue glacier mass balance Monitoring of Ossoue glacier mass balance Topographic map measurements Association Moraine Aerial images DGPS survey Stereoscopic airborne images Contour lines generation stereoscopic satellite images DEM generation

5 Regional climate-proxy generation : tools and methods Winter and summer glaciological mass balances End of LIA t Data Topographic map Contour lines GPR survey DGPS surveys: Rock Ice Satellite stereoscopic images Pre-processed data DEM DEM DEM DEM DEM DEM DEM Processing DEMs difference Elevation differences on stable bedrock Mass balances differences Elevation differences Results: Climate-proxy serie Method Geodetic mass balance Glaciological mass balance Methodological assessment Proxy timelife estimation

6 Methodological assessment example: assessment of a DEM generated by Pléiades stereoscopic images Median=Average= Standard deviation= Average= -1,37 Median= -1,46 Standard deviation=1, DEM Resolution Accuracy (x,y) 2m 2.9m (z) 1m 1.8m 1 Marti et al 214 (Pléiades days)

7 Methodological assessment example: comparison of glaciological and geodetic mass balances ( ) 45 Geodetic mass balance histogram and stakes sampling Balises Glaciological mass balace Geodetic mass balance Δ Mass balances Central mass balance Peripheral mass balance Ossoue mass balance m.w.e m.w.e m Under sampling Residual and peripheral accumulation seems under-estimated in glaciological mass balance for an exceptional snowy hydrological year(213). Δ Mass balances (glaciologic-geodetic) = -.96m

8 Regional climate-proxy generation : reconstruction of Ossoue glacier mass balance Ossoue cumulated mass balance Toral mass balance Topographic map and GPS measurements

9 Regional climate-proxy generation : Ossoue glacier mass balance monitoring Ossoue stakes elevation differences from 21 to 213 in m.w.e

10 End of LIA t Reconstruction of Ossoue glacier mass balance Monitoring of Ossoue glacier mass balance Topographic map and GPS measurements Generation of a consistent regional climate-proxy in high elevated Pyrenean context. Methodological assessments.