Abstract
Abstract. The ongoing glacier shrinkage in the Alps requires frequent updates of glacier outlines to provide an accurate database for monitoring, modelling purposes (e.g. determination of run-off, mass balance, or future glacier extent), and other applications. With the launch of the first Sentinel-2 (S2) satellite in 2015, it became possible to create a consistent, Alpine-wide glacier inventory with an unprecedented spatial resolution of 10 m. The first S2 images from August 2015 already provided excellent mapping conditions for most glacierized regions in the Alps and were used as a base for the compilation of a new Alpine-wide glacier inventory in a collaborative team effort. In all countries, glacier outlines from the latest national inventories have been used as a guide to compile an update consistent with the respective previous interpretation. The automated mapping of clean glacier ice was straightforward using the band ratio method, but the numerous debris-covered glaciers required intense manual editing. Cloud cover over many glaciers in Italy required also including S2 scenes from 2016. The outline uncertainty was determined with digitizing of 14 glaciers several times by all participants. Topographic information for all glaciers was obtained from the ALOS AW3D30 digital elevation model (DEM). Overall, we derived a total glacier area of 1806±60 km2 when considering 4395 glaciers >0.01 km2. This is 14 % (−1.2 % a−1) less than the 2100 km2 derived from Landsat in 2003 and indicates an unabated continuation of glacier shrinkage in the Alps since the mid-1980s. It is a lower-bound estimate, as due to the higher spatial resolution of S2 many small glaciers were additionally mapped or increased in size compared to 2003. Median elevations peak around 3000 m a.s.l., with a high variability that depends on location and aspect. The uncertainty assessment revealed locally strong differences in interpretation of debris-covered glaciers, resulting in limitations for change assessment when using glacier extents digitized by different analysts. The inventory is available at https://doi.org/10.1594/PANGAEA.909133 (Paul et al., 2019).
Highlights
Information on glacier extents is required for numerous glaciological and hydrological calculations, ranging from the determination of glacier volume, surface mass balance, and future glacier evolution to run-off, hydropower production, and sea level rise (e.g. Marzeion et al, 2017)
We present a new glacier inventory for the European Alps that has been compiled from S2 data that were mostly acquired within 2 weeks of August 2015
We investigated the ALOS AW3D30 digital elevation model (DEM) that was compiled from ALOS tristereo scenes (Takaku et al, 2014) and acquired about 5 years before the TDX DEM
Summary
Information on glacier extents is required for numerous glaciological and hydrological calculations, ranging from the determination of glacier volume, surface mass balance, and future glacier evolution to run-off, hydropower production, and sea level rise (e.g. Marzeion et al, 2017). Marzeion et al, 2017) For these and several other applications, glacier outlines spatially constrain all calculations and provide an important baseline dataset. In response to the ongoing atmospheric warming, glaciers retreat, shrink, and lose mass in most regions of the world A frequent update of glacier inventories is required to reduce uncertainties in subsequent. F. Paul et al.: Glacier shrinkage in the Alps continues unabated calculations. With relative area loss rates of about 1 % a−1 in many regions globally (Vaughan et al, 2013), glaciers lose about 10 % of their area within a decade, and a decadal update frequency seems sensible. Glacier inventories are often compiled from images acquired over several years, resulting in a temporarily inhomogeneous dataset. A 3-year period of acquisition is still acceptable in error terms, as area changes of about ±3 % are within the typical area uncertainty of about 3 % to 5 % (e.g. Paul et al, 2013)
Sign-in/Register to view highlights & summary Sign-in/Register to access full text options 
Talk to us
Join us for a 30 min session where you can share your feedback and ask us any queries you have
Schedule a callDisclaimer: All third-party content on this website/platform is and will remain the property of their respective owners and is provided on "as is" basis without any warranties, express or implied. Use of third-party content does not indicate any affiliation, sponsorship with or endorsement by them. Any references to third-party content is to identify the corresponding services and shall be considered fair use under The CopyrightLaw.
