Surface elevation change and mass balance of Icelandic ice caps derived from swath mode CryoSat‐2 altimetry

Abstract

We apply swath processing to CryoSat‐2 interferometric mode data acquired over the Icelandic ice caps to generate maps of rates of surface elevation change at 0.5 km postings. This high‐resolution mapping reveals complex surface elevation changes in the region, related to climate, ice dynamics, and subglacial geothermal and magmatic processes. We estimate rates of volume and mass change independently for the six major Icelandic ice caps, 90% of Iceland's permanent ice cover, for five glaciological years between October 2010 and September 2015. Annual mass balance is highly variable; during the 2014/2015 glaciological year, the Vatnajökull ice cap (~70% of the glaciated area) experienced positive mass balance for the first time since 1992/1993. Our results indicate that between glaciological years 2010/2011and 2014/2015 Icelandic ice caps have lost 5.8 ± 0.7 Gt a−1 on average, ~40% less than the preceding 15 years, contributing 0.016 ± 0.002 mm a−1 to sea level rise.

Channelized Melting Drives Thinning Under a Rapidly Melting Antarctic Ice Shelf

“…To this effect, we use ice velocity obtained from tracking of radar observation by the European Space Agency Sentinel‐1a mission between 2013 and 2016 (Rignot et al, ; Rignot et al, ) (supporting information) to calculate and assign the position that each CryoSat‐2 swath elevation measurements would have had at the beginning of the CryoSat‐2 period, set at July 2010. The rates of surface elevation change and a Digital Elevation Model are then derived using a plane fit approach (Foresta et al, ) applied to the swath CryoSat‐2 elevations. The map of linear rates of surface elevation change between 2010 and 2016, , and the swath Digital Elevation Model, c 2 , is solved on a grid of 500 m posting.…”

Short‐term variations of Icelandic ice cap mass inferred from cGPS coordinate time series

“…Ice cap height and extent derived from aerial photographs, Synthetic Aperture Radar (SAR) [e.g., Magnússon et al ., ; Gudmundsson et al ., ], and lidar [e.g., Jóhannesson et al ., ], which provide insight into changes over multiple years, field stake‐based surface mass balance measurements, which identify total mass loss from year‐to‐year [e.g., Björnsson et al ., ], and Gravity Recovery and Climate Experiment (GRACE)‐derived mass change estimates [e.g., Wouters et al ., ; Jacob et al ., ; Sørensen et al ., ], allow us to track how Icelandic ice caps have responded to climactic changes over multiyear and decadal time scales. Since the mid‐1990s, Icelandic ice caps have been losing mass at a rate of 5.8–11.4 Gt / yr [ Wouters et al ., ; Jacob et al ., ; Björnsson et al ., ; Zhao et al ., ; Foresta et al ., ; Sørensen et al ., ], a direct result of increasing summer temperatures.…”

“…Since the mid-1990s, Icelandic ice caps have been losing mass at a rate of 5. 8-11.4 Gt/yr [Wouters et al, 2008;Jacob et al, 2012;Bj€ ornsson et al, 2013;Zhao et al, 2014;Foresta et al, 2016;Sørensen et al, 2017], a direct result of increasing summer temperatures.…”

Glacier change along West Antarctica's Marie Byrd Land Sector and links to inter-decadal atmosphere–ocean variability

“…To obtain surface elevation changes over the CryoSat-2 era, we applied a novel, recently documented swath processing technique (Foresta et al, 2016;Gourmelen et al, 2017a) to CryoSat-2 Synthetic Aperture Radar Interferometric (SARIn) mode data acquired between 2010 and 2016 over the MBLS. Previously applied to other regions of Antarctica (Christie et al, 2016;Smith et al, 2017;Gourmelen et al, 2017a), this technique offers 1 to 2 orders of magnitude more elevation measurements than conventional point-of-closestapproach (POCA) altimetry techniques, thereby maximizing spatial coverage and spatial-temporal resolution of icesheet marginal areas, including over floating ice (Gourmelen et al, 2017a).…”

“…Over floating ice, CryoSat-2 era surface elevation change rates were transformed into thickness change rates using the same methodology as for ICESat data, with a propagated uncertainty of ±0.30 m yr −1 . Three-monthly shelf-averaged thickness change rates were also obtained as part of the swath processing technique, using the methodology of Foresta et al (2016), prior to the Lagrangian correction detailed above. This permitted the comparison of mean shelf-ice thickness changes against the 2003-2008 (ICESat era) and longer-term radar-altimetry-derived record (Paolo et al, 2015, see also Sect.…”