Potentials and challenges of the free SPOT 5 HRS stereo archive to derive glacier elevation changes: an evaluation in the alpine region and Iceland
Assigned Session: FS 3.134: Remote sensing to capture the dynamics of mountain cryosphere
Abstract ID: 3.12689 | Not reviewed | Requested as: Talk | TBA | TBA
Francesco Ioli (1)
Enrico, Mattea (2); Webster, Clare (1); Piermattei, Livia (1)
(1) University of Zurich, Winterthurerstrasse 190, 8057, Zurich, Switzerland
(2) University of Fribourg, Ch. du Musee 4, 1700, Fribourg, Switzerland
Abstract
Satellite stereo photogrammetry is widely used to quantify glacier elevation changes and compute geodetic mass balances on regional to global scales. Several satellite sensors support stereo imaging for DEM generation, including Terra ASTER, SPOT 5 HRS, SPOT 6-7 NAOMI, Pléiades HiRI, and Pléiades Neo Imager. Each has trade-offs in spatial resolution, temporal coverage, and data availability. ASTER, launched in 2000 and still operational for a few years, provides the longest freely available global stereo archive, but the coarse ~30 m DEM resolution limits its ability to capture changes in small glaciers. SPOT 6-7 and Pléiades offer finer resolutions (1.5 m–0.3 m) but are constrained by shorter time series, higher costs, and limited stereo archives. The Pléiades Glacier Observatory provides 2 m DEMs for 140 glacierized areas with ~5-year revisit intervals, though its time series begins only in 2016. SPOT 5 HRS, operational from 2002 to 2015, offers global coverage enabling 10 m resolution DEMs, ~4.5 times finer than ASTER. Since 2021, CNES has made SPOT 5 imagery freely available via the SPOT World Heritage program, yet it remains underutilized in glaciology.
This study assesses the capabilities and challenges of the SPOT 5 HRS archive for glacier elevation changes. We analyzed SPOT 5 spatial and temporal coverage in two RGI glacier regions: the Central European Alps (small to medium mountain and valley glaciers) and Iceland (large ice caps and low-elevation glacier complexes). SPOT 5 DEMs were generated using Ames Stereo Pipeline, then post-processed for co-registration, filtering, and void filling. Glacier elevation changes were estimated by DEM differencing. Multi-decade trends are assessed by integrating SPOT 6-7, Pléiades and ArticDEM data and analyzing time series of changes. Results were compared with ASTER-derived estimates.
Challenges with SPOT 5 imagery include 8-bit radiometric resolution, irregular revisit times, lack of Rational Polynomial Coefficients (RPC) camera models, and rectangular pixels (10 m image resolution with 5 m along-track oversampling).
Despite these limitations, the SPOT 5 HRS archive is a valuable resource for the glaciological community, providing high-resolution elevation change estimates for the early 2000s and filling a critical data gap.
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