Abstract
AbstractAnnual equilibrium-line altitude (ELA) and surface mass balance of Glacier Blanc, Ecrins region, French Alps, were reconstructed from a 25 year time series of satellite images (1981–2005). The remote-sensing method used was based on identification of the snowline, which is easy to discern on optical satellite images taken at the end of the ablation season. In addition, surface mass balances at the ELA were reconstructed for the same period using meteorological data from three nearby weather stations. A comparison of the two types of series reveals a correlation of r > 0.67 at the 0.01 level of significance. Furthermore, the surface mass balances obtained from remote-sensing data are consistent with those obtained from field measurements on five other French glaciers (r = 0.76, p < 0.01). Also consistent for Glacier Blanc is the total mass loss (10.8 m w.e.) over the studied period. However, the surface mass balances obtained with the remote-sensing method show lower interannual variability. Given that the remote-sensing method is based on changes in the ELA, this difference probably results from the lower sensitivity of the surface mass balance to climate parameters at the ELA.
Highlights
Both the equilibrium-line altitude (ELA) and annual surface mass balance depend on the climatic conditions that govern accumulation and ablation processes at the glacier surface (Lliboutry, 1965; Martin, 1975; Kuhn, 1989; Paterson, 1994; Vincent, 2002; Hooke, 2005)
We first present the measurements of the ELA and compare our results with the few ELA measurements made on Glacier Blanc
We present the remote-sensing surface mass-balance series based on the ELA variation and compare it with field and meteorological surface mass balances computed for Glacier Blanc, and with field surface mass-balance series from five other French glaciers
Summary
Both the equilibrium-line altitude (ELA) and annual surface mass balance depend on the climatic conditions that govern accumulation and ablation processes at the glacier surface (Lliboutry, 1965; Martin, 1975; Kuhn, 1989; Paterson, 1994; Vincent, 2002; Hooke, 2005). The advantage of using glacier ELA and surface mass balance as climate indicators, over other glaciological parameters such as surface area or length, is that they can be interpreted more directly in terms of climate signals. Long series are necessary to study climate at high altitudes, where meteorological data are very scarce (Vincent, 2002), as well as to better understand the relationship between glaciers and climate. We need this understanding to improve our knowledge of past climate variations and the future evolution of glaciers in the current context of global climate change (Dyugerov, 2000). Long series are needed for the numerical modelling of glaciers (Gudmundsson, 1999; Le Meur and Vincent, 2003)
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