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Abstract:
This work is part of the Glacier Mass Balance Intercomparison Exercise (GlaMBIE), which aims to collect and analyze regional assessments of glacier mass balance across the range of available methods. Here we present our assessment of glacier elevation change in the Svalbard region from spaceborne optical data using the geodetic method. We have developed an approach based on extrapolating elevation values over 10-year time intervals using the ASTER and SPOT-5 DEM time series available over the region. Our approach consists of using the time series of co-registered summer DEMs (from July to October) to derive the median elevation within fixed elevation bands (e.g. bins of 100 m), interpolate the median elevation data points over time using a RANSAC (RANdom SAmple Consensus) linear interpolation, and extrapolate the elevation information for each band that corresponds to the pre-defined period. We then derived the area-weighted mean to calculate elevation changes over each glacier based on RGI6.0.This approach is different from other multi-temporal approaches, which commonly assess the elevation evolution of individual pixels (or a window filter) and then aggregate the derived trends in a second step (e.g. Hugonnet et al. 2021). Therefore, we compared our results with already available methods for deriving elevation change estimates from the geodetic method by comparing regional assessment and individual glacier estimates. This work also aims to discuss the challenges related to spaceborne optical DEMs for calculating glacier elevation change, including issues and different approaches related to co-registration, noise filtering, and gap filling.
