Monitoring of seasonal glacier mass balance over the European Alps using low-resolution optical satellite images

Abstract

ABSTRACT. We explore a new method to retrieve seasonal glacier mass balances (MBs) from lowresolution optical remote sensing. We derive annual winter and summer snow maps of the Alps during 1998-2014 using SPOT/VEGETATION 1 km resolution imagery. We combine these seasonal snow maps with a DEM to calculate a 'mean regional' altitude of snow (Z) in a region surrounding a glacier. Then, we compare the interannual variation of Z with the observed winter/summer glacier MB for 55 Alpine glaciers over 1998-2008, our calibration period. We find strong linear relationships in winter (mean R 2 = 0.84) and small errors for the reconstructed winter MB (mean RMSE = 158 mm (w.e.) a −1). This is lower than errors generally assumed for the glaciological MB measurements (200-400 mm w.e. a ) and slightly larger errors in summer (RMSE = 561 mm w.e. a −1). These results indicate that our approach might be valuable for remotely determining the seasonal MB of glaciers over large regions.

Annual and Seasonal Glacier-Wide Surface Mass Balance Quantified from Changes in Glacier Surface State: A Review on Existing Methods Using Optical Satellite Imagery

“…The NDSI value is proportional to the snow cover fraction inside the pixel and allows an efficient monitoring of the spatial and temporal snow cover variations [50]. In Drolon et al [51], an NDSI adapted to the SPOT/VGT sensor was proposed, inspired by Chaponnière et al [50], computed from the mean of the red (B0) and blue (B2) channels and from the SWIR band:…”

“…This method has been applied for 55 glaciers in the European Alps with SPOT/VGT images by Drolon et al [51]. Promising linear relationships between the regional mean snow altitude and observed seasonal SMB have been found over the calibration period 1998/1999-2008.…”

“…Beside the individual calculation of each glacier SMB presented in Drolon et al [51], we illustrate here a synthetic result through the mean reconstructed and observed MB time series averaged for the 55 studied glaciers (Figure 11). In winter (Figure 11a), <B w_VGT > is generally in close agreement with <B w_obs >.…”

“…Thus, no SMB can be retrieved, except if the WOSM size is increased (but at the cost of degrading the regression quality). Moreover, the snow-map method does not seem to perform well for large glaciers (e.g., Aletsch Glacier in the case of the application in the European Alps; see [51]), whose ablation area reaches relatively low elevation. Glacier snout can thus remain snow-free for a considerable part of the period used for winter SMB estimate (October-April).…”

The Potential of Earth Observation for the Analysis of Cold Region Land Surface Dynamics in Europe—A Review

“…Among them, taking advantage of the significant spectral contrast between the Short Wave Infra-Red (SWIR) and the visible band, the band ratio method (thresholding ratio image, e.g., [76][77][78][79]) is the most widely acknowledged and utilized algorithm. Taking Landsat TM band configuration as an example, commonly selected band ratios (hereafter in this section we exemplify them by Landsat TM bands) are: (1) TM3/TM5 [80][81][82][83], (2) TM4/TM5 [76][77][78], (3) Normalized Difference Snow Index (NDSI) [84]:…”