Winter mass balance of Drangajökull ice cap (NW Iceland) derived from satellite sub-meter stereo images

Abstract

Abstract. Sub-meter resolution, stereoscopic satellite images allow for the generation of accurate and high-resolution digital elevation models (DEMs) over glaciers and ice caps. Here, repeated stereo images of Drangajökull ice cap (NW Iceland) from Pléiades and WorldView2 (WV2) are combined with in situ estimates of snow density and densification of firn and fresh snow to provide the first estimates of the glacier-wide geodetic winter mass balance obtained from satellite imagery. Statistics in snow- and ice-free areas reveal similar vertical relative accuracy (< 0.5 m) with and without ground control points (GCPs), demonstrating the capability for measuring seasonal snow accumulation. The calculated winter (14 October 2014 to 22 May 2015) mass balance of Drangajökull was 3.33 ± 0.23 m w.e. (meter water equivalent), with ∼ 60 % of the accumulation occurring by February, which is in good agreement with nearby ground observations. On average, the repeated DEMs yield 22 % less elevation change than the length of eight winter snow cores due to (1) the time difference between in situ and satellite observations, (2) firn densification and (3) elevation changes due to ice dynamics. The contributions of these three factors were of similar magnitude. This study demonstrates that seasonal geodetic mass balance can, in many areas, be estimated from sub-meter resolution satellite stereo images.

Multi-year evaluation of airborne geodetic surveys to estimate seasonal mass balance, Columbia and Rocky Mountains, Canada

“…Regional observations of late summer snow density are consistent (Table 5), ranging from 530 to 630 kg m −3 for glaciers across the Pacific Northwest (Table 5). This is expected for temperate, midlatitude glaciers, where snow densities range from the critical density of about 550 kg m −3 (Benson, 1962;Herron and Langway, 1980) to around 600 kg m −3 depending upon regional climatology. Since we independently evaluate glaciological versus geodetic estimates of mass change, we compare application of our late summer glaciological snow density measurements to calculate net balance with estimates based on the average of typical observations from four regional sources (590 ± 60 kg m −3 ; Table 5), to test the impact of uncertainties of up to 10 % in this parameter.…”

Volume Changes of Elbrus Glaciers From 1997 to 2017

“…The DEM (4 m resolution) was generated using the Ames Stereo Pipeline of Pléiades images acquired on 8 September 2017 (Shean et al, 2016). The vertical precision of the Pléiades DEM was assessed earlier (Berthier et al, 2014;Marti et al, 2016;Belart et al, 2017) and generally is between ± 0.5 m ± 1 m. The 1997 DEM was obtained as a result of an aerial photography survey conducted on 8 September 1997 by the Faculty of Geography, Moscow State University. The methodology is described in detail in Zolotarev and Kharkovets (2000).…”

Évolution recente des glaciers du Vignemale (2013-2017)

“…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). La version d'ASP utilisée pour cette étude est la 5.2.1.…”