Implications of changing scattering properties on Greenland ice sheet volume change from Cryosat-2 altimetry

Simonsen, Sebastian B.; Sørensen, Louise Sandberg

doi:10.1016/j.rse.2016.12.012

Cited by 57 publications

(104 citation statements)

References 36 publications

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“…Using the earliest full regional velocity map (1995/96) and the most recent record (2015/16), the rate of annual velocity change was calculated over this 20-year period. 30 We use surface elevation change (SEC) data from ERS-1, ERS-2, Envisat, and Cryosat-2 radar altimetry for 1992 to 2015, and made available by the ESA's Greenland Ice Sheet CCI project (Khvorostovsky, 2012;Simonsen and Sørensen, 2017 , 2015). Data from 1992 to 2011 were derived from the ERS-1, ERS-2 and Envisat satellites, using a combination of cross-over and repeat track analysis, which have then been merged to create a continuous dataset across satellites (Khvorostovsky, 2012).…”

Section: Ice Velocity and Surface Elevationmentioning

confidence: 99%

“…These data are provided in 5-year running means from 1992 to 2011 and at a resolution of 5 km. For the most recent SEC (2011 to 2015), we used Crysosat-2 satellite elevation change which are provided in 2-year means (Simonsen and Sørensen, 2017). These data were generated using the Least Mean Squares method, where grid cells were 5 subtracted from the Greenland Ice Mapping Project (GIMP) DEM and corrected for backscatter and leading edge width (Simonsen and Sørensen, 2017).…”

Section: Ice Velocity and Surface Elevationmentioning

confidence: 99%

“…For the most recent SEC (2011 to 2015), we used Crysosat-2 satellite elevation change which are provided in 2-year means (Simonsen and Sørensen, 2017). These data were generated using the Least Mean Squares method, where grid cells were 5 subtracted from the Greenland Ice Mapping Project (GIMP) DEM and corrected for backscatter and leading edge width (Simonsen and Sørensen, 2017). Calculations were made at a 1 km grid resolution and resampled to 5 km to conform with 1992-2011 datasets (Simonsen and Sørensen, 2017).…”

Section: Ice Velocity and Surface Elevationmentioning

confidence: 99%

“…These data were generated using the Least Mean Squares method, where grid cells were 5 subtracted from the Greenland Ice Mapping Project (GIMP) DEM and corrected for backscatter and leading edge width (Simonsen and Sørensen, 2017). Calculations were made at a 1 km grid resolution and resampled to 5 km to conform with 1992-2011 datasets (Simonsen and Sørensen, 2017). Using error estimates (Simonsen and Sørensen, 2017), we calculated mean errors across all years and across all northern Greenland drainage basins to be ±0.14 m a Profile data from all velocity and surface elevation time series were extracted along each glacier centreline, which were drawn following the method of Lea et al (2014).…”

Section: Ice Velocity and Surface Elevationmentioning

confidence: 99%

“…Calculations were made at a 1 km grid resolution and resampled to 5 km to conform with 1992-2011 datasets (Simonsen and Sørensen, 2017). Using error estimates (Simonsen and Sørensen, 2017), we calculated mean errors across all years and across all northern Greenland drainage basins to be ±0.14 m a Profile data from all velocity and surface elevation time series were extracted along each glacier centreline, which were drawn following the method of Lea et al (2014). The Euclidean distance was calculated between parallel fjord walls that were digitised in 2015 Landsat 8 imagery.…”

Section: Ice Velocity and Surface Elevationmentioning

confidence: 99%

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Dynamic changes in outlet glaciers in northern Greenland from 1948 to 2015

Hill¹,

Carr²,

Stokes³

et al. 2018

Preprint

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The Greenland Ice Sheet (GrIS) is losing mass in response to recent climatic and oceanic warming. Since the mid-1990s, marine-terminating outlet glaciers across the GrIS have retreated, accelerated and thinned, but recent changes in northern 10Greenland have been comparatively understudied. Consequently, the dynamic response (i.e. changes in surface elevation and velocity) of these outlet glaciers to changes at their termini, particularly calving from floating ice tongues, remains unknown.Here we use satellite imagery and historical maps to produce an unprecedented 68-year record of terminus change across 18 major outlet glaciers and combine this with previously published surface elevation and velocity datasets. Overall, recent (1995Overall, recent ( -2015 retreat rates were higher than at any time in the previous 47 years, but change-point analysis reveals three categories of 15 frontal position change: (i) minimal change followed by steady and continuous retreat, (ii) minimal change followed by a switch to a period of short-lived rapid retreat, (iii) glaciers that underwent cycles of advance and retreat. Furthermore, these categories appear to be linked to the terminus type, with those in category (i) having grounded termini and those in category (ii) characterised by floating ice tongues. We interpret glaciers in category (iii) as surge-type. Glacier geometry (e.g. fjord width and basal topography) is also an important influence on the dynamic re-adjustment of glaciers to changes at their termini. 20Taken together, the loss of several ice tongues and the recent acceleration in the retreat of numerous marine-terminating glaciers suggests northern Greenland is undergoing rapid change and could soon impact on some large catchments that have capacity to contribute an important component to sea level rise.

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Section: Ice Velocity and Surface Elevationmentioning

confidence: 99%

Section: Ice Velocity and Surface Elevationmentioning

confidence: 99%

Section: Ice Velocity and Surface Elevationmentioning

confidence: 99%

Section: Ice Velocity and Surface Elevationmentioning

confidence: 99%

Section: Ice Velocity and Surface Elevationmentioning

confidence: 99%

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Dynamic changes in outlet glaciers in northern Greenland from 1948 to 2015

Hill¹,

Carr²,

Stokes³

et al. 2018

Preprint

View full text Add to dashboard Cite

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Mass Balances of the Antarctic and Greenland Ice Sheets Monitored from Space

et al. 2023

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Satellite data have revealed that the Greenland and Antarctic Ice Sheets are changing rapidly due to warming air and ocean temperatures. Crucially, Earth Observations can now be used to measure ice sheet mass balance at the continental scale, which can help reduce uncertainties in the ice sheets’ past, present, and future contributions to global mean sea level. The launch of satellite missions dedicated to the polar regions led to great progress towards a better assessment of the state of the ice sheets, which, in combination with ice sheet models, have furthered our understanding of the physical processes leading to changes in the ice sheets' properties. There is now a three-decade-long satellite record of Antarctica and Greenland mass changes, and new satellite missions are planned to both continue this record and further develop our observational capabilities, which is critical as the ice sheets remain the most uncertain component of future sea-level rise. In this paper, we review the mechanisms leading to ice sheets' mass changes and describe the state of the art of the satellite techniques used to monitor Greenland’s and Antarctica’s mass balance, providing an overview of the contributions of Earth Observations to our knowledge of these vast and remote regions.

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How Different Analysis and Interpolation Methods Affect the Accuracy of Ice Surface Elevation Changes Inferred from Satellite Altimetry

2020

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Satellite altimetry has been widely used to determine surface elevation changes in polar ice sheets. The original height measurements are irregularly distributed in space and time. Gridded surface elevation changes are commonly derived by repeat altimetry analysis (RAA) and subsequent spatial interpolation of height change estimates. This article assesses how methodological choices related to those two steps affect the accuracy of surface elevation changes, and how well this accuracy is represented by formal uncertainties. In a simulation environment resembling CryoSat-2 measurements acquired over a region in northeast Greenland between December 2010 and January 2014, different local topography modeling approaches and different cell sizes for RAA, and four interpolation approaches are tested. Among the simulated cases, the choice of either favorable or unfavorable RAA affects the accuracy of results by about a factor of 6, and the different accuracy levels are propagated into the results of interpolation. For RAA, correcting local topography by an external digital elevation model (DEM) is best, if a very precise DEM is available, which is not always the case. Yet the best DEM-independent local topography correction (nine-parameter model within a 3,000 m diameter cell) is comparable to the use of a perfect DEM, which exactly represents the ice sheet topography, on the same B Undine Strößenreuther

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Implications of changing scattering properties on Greenland ice sheet volume change from Cryosat-2 altimetry

Cited by 57 publications

References 36 publications

Dynamic changes in outlet glaciers in northern Greenland from 1948 to 2015

Dynamic changes in outlet glaciers in northern Greenland from 1948 to 2015

Mass Balances of the Antarctic and Greenland Ice Sheets Monitored from Space

How Different Analysis and Interpolation Methods Affect the Accuracy of Ice Surface Elevation Changes Inferred from Satellite Altimetry

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