Glacial-geodetic long-term (1991-2014) measurements on elevation change, ice surface deformation, and ice flow velocity in the Swiss Camp area on the Greenland ice sheet
The recent acceleration of mass loss of the Greenland ice sheet as determined from large-scale, satellite-derived geodetic and gravimetric observations is well documented. However, longer-term in situ elevation change measurements are scarce. Here, we present a 23-year time series (1991 to 2014) of...
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| Format: | Dataset |
| Language: | English |
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PANGAEA
2019
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| Online Access: | https://doi.pangaea.de/10.1594/PANGAEA.900785 https://doi.org/10.1594/PANGAEA.900785 |
| Summary: | The recent acceleration of mass loss of the Greenland ice sheet as determined from large-scale, satellite-derived geodetic and gravimetric observations is well documented. However, longer-term in situ elevation change measurements are scarce. Here, we present a 23-year time series (1991 to 2014) of bi-annual in situ geodetic observations at two sites in West Greenland. Repeated GPS measurements at Swiss Camp (1170 m a.s.l.) and 15 km downglacier at site ST2 (1100 m a.s.l.) were used to determine elevation changes, ice flow velocities, and strain rates. Meteorological observations were used to interpret the results. These were compared to satellite-derived evaluations. Surface elevation at Swiss Camp dropped by 14.4 m between 1991 and 2014 (0.62 m/year on average) with accelerated elevation drops in recent years. The same tendency was also apparent at ST2. Here the surface elevation dropped by 12.2 m between 2004 and 2014 (1.2 m/year on average). The elevation changes were not constant over the survey areas, there were, however, pronounced systematic local differences. The causes of these (e.g. albedo, humidity, etc.) have not yet been established. The velocity of flow does not behave uniformly. At SWC the ice flows faster (0.32 m/d) than at ST2 (0.19 m/d), and although at SWC acceleration arises, ST2 demonstrates a reduction in speed, probably because of the ascending border mountains. Strain rates vary strongly and show that the local underground of the moved measuring field affects the results strongly. The strain rates in longitudinal direction between both sites are negative, indicating compression of the ice, which results in dynamic thickening. The influence of individual meteorological parameters on the elevation changes was examined using correlation analysis. However, significant correlations were rarely found; in both survey areas these were most clear for the summer albedo. Air temperature and net radiation proved to be less relevant. Comparisons of the geodetic mass balance with the specific SMB from ... |
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