Estimation of volume change rates of Greenland's ice sheet from ICESat data using overlapping footprints

Slobbe, Cornelis; Lindenbergh, R.C.; Ditmar, Pavel

doi:10.1016/j.rse.2008.07.004

Cited by 72 publications

(65 citation statements)

References 19 publications

Supporting

Mentioning

Contrasting

Order By: Relevance

“…The system is closed by ice motion and it was essentially in balance in the decade preceding this millennium (Zwally et al, 2005;van den Broeke et al, 2009;Rignot et al, 2011). For the present state, this mass turn-over is stated to be out of balance and recent estimates for current mass loss rates based on gravimetry (Luthke et al, 2006;Velicogna et al, 2009;Schrama and Wouters, 2011), on radar/laser altimetry (Slobbe et al, 2008;Sørensen et al, 2011;Zwally et al, 2011;Moon et al, 2012), and on approaches combining discharge estimates from satellite interferometry with surface mass balance modelling (van den Broeke et al, 2009;Rignot et al, 2011) range from 0.3-0.8 mm s.l.e. yr −1 (sea level equivalent) (110-290 Gt yr −1 ).…”

Section: Introductionmentioning

confidence: 99%

Effect of higher-order stress gradients on the centennial mass evolution of the Greenland ice sheet

2013

View full text Add to dashboard Cite

Abstract. We use a three-dimensional thermo-mechanically coupled model of the Greenland ice sheet to assess the effects of marginal perturbations on volume changes on centennial timescales. The model is designed to allow for five ice dynamic formulations using different approximations to the force balance. The standard model is based on the shallow ice approximation for both ice deformation and basal sliding. A second model version relies on a higher-order Blatter/Pattyn type of core that resolves effects from gradients in longitudinal stresses and transverse horizontal shearing, i.e. membrane-like stresses. Together with three intermediate model versions, these five versions allow for gradually more dynamic feedbacks from membrane stresses. Idealised experiments are conducted on various resolutions to compare the time-dependent response to imposed accelerations at the marine ice front. If such marginal accelerations are to have an appreciable effect on total mass loss on a century timescale, a fast mechanism to transmit such perturbations inland is required. While the forcing is independent of the model version, inclusion of direct horizontal coupling allows the initial speed-up to reach several tens of kilometres inland. Within one century, effects from gradients in membrane stress alter the inland signal propagation and transmit additional dynamic thinning to the ice sheet interior. But the centennial overall volume loss differs only by some percents from the standard model, as the dominant response is a diffusive inland propagation of geometric changes. For the experiments considered, this volume response is even attenuated by direct horizontal coupling. The reason is a faster adjustment of the sliding regime by instant stress transmission in models that account for the effect of membrane stresses. Ultimately, horizontal coupling decreases the reaction time to perturbations at the ice sheet margin. These findings suggest that for modelling the mass evolution of a large-scale ice sheet, effects from diffusive geometric adjustments dominate effects from successively more complete dynamic approaches.

show abstract

Section: Introductionmentioning

confidence: 99%

Effect of higher-order stress gradients on the centennial mass evolution of the Greenland ice sheet

2013

View full text Add to dashboard Cite

show abstract

“…It is also possible to derive the ice mass balance in a more straightforward way, i.e., without building models describing the ice behavior. Apart from satellite gravimetry, a number of remote sensing techniques can be used for that purpose: satellite radar altimetry (Zwally et al 2005), satellite laser altimetry (Zwally et al 2002(Zwally et al , 2011Slobbe et al 2008;Sørensen et al 2011), airborne laser altimetry (Abdalati et al 2001;Krabill et al 2004), and stereo satellite imagery (Stearns et al 2007). All these observation techniques deduce the mass balance of the ice sheets from measurements of elevation changes and lead to a relatively high spatial resolution.…”

Section: Introductionmentioning

confidence: 99%

Estimation of mass change trends in the Earth’s system on the basis of GRACE satellite data, with application to Greenland

Siemes

Ditmar

Riva

et al. 2012

J Geod

View full text Add to dashboard Cite

The Gravity Recovery and Climate Experiment (GRACE) satellite mission measures the Earth's gravity field since March 2002. We propose a new filtering procedure for post-processing GRACE-based monthly gravity field solutions provided in the form of spherical harmonic coefficients. The procedure is tuned for the optimal estimation of linear trends and other signal components that show a systematic behavior over long time intervals. The key element of the developed methodology is the statistically optimal Wienertype filter which makes use of the full covariance matrices of noise and signal. The developed methodology is applied to determine the mass balance of the Greenland ice sheet, both per drainage system and integrated, as well as the mass balance of the ice caps on the islands surrounding Greenland. The estimations are performed for three 2-year time intervals (2003-2004, 2005-2006, and 2007-2008), as well as for the 6-year time interval (2003)(2004)(2005)(2006)(2007)(2008). The study confirms a significant difference in the behavior of the drainage systems over time. The average 6-year rate of mass loss in Greenland is estimated as 165 ± 15 Gt/year. The rate of mass loss of the ice caps on Ellesmere Island (together with Devon Island), Baffin Island, Iceland, and Svalbard is found to be 22 ± 4, 21 ± 6, 17 ± 9, and 6 ± 2 Gt/year, respectively. All these estimates are corrected for the effect of glacial isostatic adjustment.

show abstract

“…Common approaches are the repeat-track (RT) and cross-over (XO) techniques where measurements along repeated ground-tracks or in XO locations between ascending and descending satellite passes are explored. The different methods are described by Slobbe et al (2008); Moholdt et al (2010); Gunter et al (2014). For a number of reasons, the altimeters resolve the surface signal to varying degrees and precisions: Laser data from the NASA Ice, Cloud, and land Elevation Satellite (ICESat) illuminate ∼60 m wide ellipses, while echoes from Envisat have pulse-limited footprints of 2-10 km.…”

Section: Surface Elevation Change Studies From Altimetrymentioning

confidence: 99%

“…In any case, the local surface topography in-between ground-tracks must be considered. This can be done by estimating the slope bias from the distance between ground-tracks as well as the surface slope between them, the latter derived from an external Digital Elevation Model (DEM) (Slobbe et al 2008).…”

Section: Surface Elevation Change Studies From Altimetrymentioning

confidence: 99%

ESA ice sheet CCI: derivation of the optimal method for surface elevation change detection of the Greenland ice sheet – round robin results

Levinsen

Khvorostovsky²,

Ticconi

et al. 2015

International Journal of Remote Sensing

View full text Add to dashboard Cite

For more than two decades, radar altimetry missions have provided continuous elevation estimates of the Greenland Ice Sheet (GrIS). Here, we propose a method for using such data to estimate ice sheet-wide surface elevation changes (SEC). The final dataset will be based on observations acquired with the European Space Agency's Envisat, ERS-1 and -2, CryoSat-2, and, in the longer term, Sentinel-3 satellites. In order to find the best-performing method, an inter-comparison exercise has been carried out in which the scientific community was asked to provide their best SEC estimate as well as a feedback sheet describing the applied method. Due to the hitherto few radarbased SEC analyses as well as the higher accuracy of laser data, the participants were asked to use either Envisat radar or ICESat (Ice, Cloud, and land Elevation Satellite) laser altimetry over the Jakobshavn Isbrae drainage basin. The submissions were validated against airborne laser-scanner data, and inter-comparisons were carried out to analyze the potential in the applied methods and whether the two altimeters were capable of resolving the same signal. The analyses found great potential in the applied repeat-track and cross-over techniques, and, for the first time over Greenland, that repeat-track analyses from radar altimetry agreed well with laser data. Since topography-related errors can be neglected in cross-over analyses, it is expected that the most accurate, ice sheet-wide SEC estimates are obtained by combining the cross- * Corresponding author. E-mail:JFL@space.dtu.dk 1 November 7, 2014 International Journal of Remote Sensing tRES˙JFL˙subm over and repeat-track techniques. It is thus possible to exploit the high accuracy of the former and the large spatial data coverage of the latter. Based on CryoSat's different operation modes, and the increased spatial and temporal data coverage, this shows good potential for a future inclusion of CryoSat-2 and Sentinel-3 data to continuously obtain accurate SEC estimates both in the interior and margin ice sheet.

show abstract

Estimation of volume change rates of Greenland's ice sheet from ICESat data using overlapping footprints

Cited by 72 publications

References 19 publications

Effect of higher-order stress gradients on the centennial mass evolution of the Greenland ice sheet

Effect of higher-order stress gradients on the centennial mass evolution of the Greenland ice sheet

Estimation of mass change trends in the Earth’s system on the basis of GRACE satellite data, with application to Greenland

ESA ice sheet CCI: derivation of the optimal method for surface elevation change detection of the Greenland ice sheet – round robin results

Contact Info

Product

Resources

About