Glacier topography and elevation changes derived from Pléiades sub-meter stereo images

Abstract

Abstract. In response to climate change, most glaciers are losing mass and hence contribute to sea-level rise. Repeated and accurate mapping of their surface topography is required to estimate their mass balance and to extrapolate/calibrate sparse field glaciological measurements. In this study we evaluate the potential of sub-meter stereo imagery from the recently launched Pléiades satellites to derive digital elevation models (DEMs) of glaciers and their elevation changes. Our five evaluation sites, where nearly simultaneous field measurements were collected, are located in Iceland, the European Alps, the central Andes, Nepal and Antarctica. For Iceland, the Pléiades DEM is also compared to a lidar DEM. The vertical biases of the Pléiades DEMs are less than 1 m if ground control points (GCPs) are used, but reach up to 7 m without GCPs. Even without GCPs, vertical biases can be reduced to a few decimetres by horizontal and vertical co-registration of the DEMs to reference altimetric data on ice-free terrain. Around these biases, the vertical precision of the Pléiades DEMs is ±1 m and even ±0.5 m on the flat glacier tongues (1σ confidence level). Similar precision levels are obtained in the accumulation areas of glaciers and in Antarctica. We also demonstrate the high potential of Pléiades DEMs for measuring seasonal, annual and multiannual elevation changes with an accuracy of 1 m or bet-

Évolution recente des glaciers du Vignemale (2013-2017)

“…De plus, l'utilisation d'ASP permet d'améliorer la reproductibilité des résultats puisque le logiciel est open source. Le logiciel ASP a permis de produire des MNE à partir d'images Pléiades de glaciers ou de surfaces enneigées en zone de montagne ayant une erreur aléatoire verticale inférieure à 1 m (Berthier et al, 2014, Marti et al, 2016. De plus, l'erreur sur la différence de deux MNE Pléiades peut être réduite à 50 cm après co-registration des deux MNE (Marti et al, 2016;Belart et al, 2017).…”

“…Les images panchromatiques Pléiades ayant une résolu-tion spatiale sub-métrique, les MNE dérivés de vues sté-réoscopiques peuvent avoir une résolution spatiale de l'ordre du mètre au mieux (typiquement 2 m à 4 m), avec une erreur aléatoire par pixel inférieure à 1 m (Berthier et al, 2014;Marti et al, 2016). Par différenciation de deux MnE Pléiades acquis entre deux dates suffisamment éloi-gnées on peut donc produire une carte du bilan de masse d'un glacier avec une meilleure résolution spatiale que celle qui est permise par interpolation des mesures de balises.…”

Validation of Pleiades Tri-Stereo DSM in Urban Areas

“…By using 15 control points extracted by a LiDAR-based DSM, they achieved an RMSEz of 0.75, while Perko et al [14] following a similar approach over Innsbruck city, Austria (a direct comparison of the produced DSM over the city vs. a LiDAR-based DSM) achieved a RMSEz of 2.4 m. Bagnardi et al [7] produced a DSM using 1 m Pleiades-1A imagery in order to calculate lava flow volume after the eruption of the Fogo Volcano in Cape Verde in comparison to a pre-eruption satellite-based SAR DSM from TanDEM-X. Berthier et al [15], by using Pleiades, derived digital elevation models (DEMs) of glaciers. They noticed changes in the estimated elevation DEMs with a vertical precision at ±1 m and ±0.5 m on the flat glacier tongues (1σ confidence level).…”

Multi-decadal mass balance series of three Kyrgyz glaciers inferred from transient snowline observations

“…The two SPOT5 DEMs agency (Korona et al, 2009). The steps required to adjust the two SPOT5 DEMs horizontally and vertically to the Pléiades reference DEM are similar to the ones followed in a previous study on the Mont Blanc area (Berthier et al, 2014).…”

“…Uncertainties in elevation differences were quantified by computing the area-weighted mean of the absolute difference off- satellite data to elevation differences measured in situ (Berthier et al, 2014). For Golubin, a value of 1.8 m indicates a slightly lower DEM quality.…”