scholarly journals Greenland Ice Sheet Mass Balance (1992–2020) From Calibrated Radar Altimetry

2021 ◽  
Vol 48 (3) ◽  
Author(s):  
Sebastian B. Simonsen ◽  
Valentina R. Barletta ◽  
William T. Colgan ◽  
Louise Sandberg Sørensen
Keyword(s):  
Mass Balance ◽  
Ice Sheet ◽  
Greenland Ice Sheet ◽  
Radar Altimetry ◽  
Ice Sheet Mass Balance

Greenland ice sheet mass balance: a review

2015 ◽  
Vol 78 (4) ◽  
pp. 046801 ◽  
Author(s):  
Shfaqat A Khan ◽  
Andy Aschwanden ◽  
Anders A Bjørk ◽  
John Wahr ◽  
Kristian K Kjeldsen ◽  
...  
Keyword(s):  
Mass Balance ◽  
Ice Sheet ◽  
Greenland Ice Sheet ◽  
Ice Sheet Mass Balance

scholarly journals Monitoring southwest Greenland’s ice sheet melt with ambient seismic noise

2016 ◽  
Vol 2 (5) ◽  
pp. e1501538 ◽  
Author(s):  
Aurélien Mordret ◽  
T. Dylan Mikesell ◽  
Christopher Harig ◽  
Bradley P. Lipovsky ◽  
Germán A. Prieto
Keyword(s):  
Mass Loss ◽  
Mass Balance ◽  
Sea Level ◽  
Seismic Noise ◽  
Seismic Velocity ◽  
Ice Sheet ◽  
Greenland Ice Sheet ◽  
Sea Level Changes ◽  
Ice Sheet Mass Balance ◽  
Velocity Changes

The Greenland ice sheet presently accounts for ~70% of global ice sheet mass loss. Because this mass loss is associated with sea-level rise at a rate of 0.7 mm/year, the development of improved monitoring techniques to observe ongoing changes in ice sheet mass balance is of paramount concern. Spaceborne mass balance techniques are commonly used; however, they are inadequate for many purposes because of their low spatial and/or temporal resolution. We demonstrate that small variations in seismic wave speed in Earth’s crust, as measured with the correlation of seismic noise, may be used to infer seasonal ice sheet mass balance. Seasonal loading and unloading of glacial mass induces strain in the crust, and these strains then result in seismic velocity changes due to poroelastic processes. Our method provides a new and independent way of monitoring (in near real time) ice sheet mass balance, yielding new constraints on ice sheet evolution and its contribution to global sea-level changes. An increased number of seismic stations in the vicinity of ice sheets will enhance our ability to create detailed space-time records of ice mass variations.

scholarly journals Constraining GRACE-derived cryosphere-attributed signal to irregularly shaped ice-covered areas

2013 ◽  
Vol 7 (6) ◽  
pp. 1901-1914 ◽  
Author(s):  
W. Colgan ◽  
S. Luthcke ◽  
W. Abdalati ◽  
M. Citterio
Keyword(s):  
Monte Carlo ◽  
Mass Loss ◽  
Mass Balance ◽  
Spherical Harmonic ◽  
Ice Sheet ◽  
Greenland Ice Sheet ◽  
Ice Caps ◽  
Ice Coverage ◽  
Ice Sheet Mass Balance ◽  
Harmonic Representation

Abstract. We use a Monte Carlo approach to invert a spherical harmonic representation of cryosphere-attributed mass change in order to infer the most likely underlying mass changes within irregularly shaped ice-covered areas at nominal 26 km resolution. By inverting a spherical harmonic representation through the incorporation of additional fractional ice coverage information, this approach seeks to eliminate signal leakage between non-ice-covered and ice-covered areas. The spherical harmonic representation suggests a Greenland mass loss of 251 ± 25 Gt a−1 over the December 2003 to December 2010 period. The inversion suggests 218 ± 20 Gt a−1 was due to the ice sheet proper, and 34 ± 5 Gt a−1 (or ~14%) was due to Greenland peripheral glaciers and ice caps (GrPGICs). This mass loss from GrPGICs exceeds that inferred from all ice masses on both Ellesmere and Devon islands combined. This partition therefore highlights that GRACE-derived "Greenland" mass loss cannot be taken as synonymous with "Greenland ice sheet" mass loss when making comparisons with estimates of ice sheet mass balance derived from techniques that sample only the ice sheet proper.

scholarly journals Changes in the firn structure of the Greenland Ice Sheet caused by recent warming

2015 ◽  
Vol 9 (1) ◽  
pp. 541-565 ◽  
Author(s):  
S. de la Peña ◽  
I. M. Howat ◽  
P. W. Nienow ◽  
M. R. van den Broeke ◽  
E. Mosley-Thompson ◽  
...  
Keyword(s):  
Mass Balance ◽  
Ice Sheet ◽  
Greenland Ice Sheet ◽  
Mass Gain ◽  
High Elevation ◽  
Near Surface ◽  
Surface Mass ◽  
Ice Sheet Mass Balance ◽  
Ice Content ◽  
Percolation Zone

Abstract. Atmospheric warming over the Greenland Ice Sheet during the last two decades has increased the amount of surface meltwater production, resulting in the migration of melt and percolation regimes to higher altitudes and an increase in the amount of solid ice from refrozen meltwater found in the firn above the equilibrium line. Here we present observations of near-surface (0–20 m) firn conditions in western Greenland obtained from campaigns between 1998 and 2014. We find a sharp increase in firn ice content in the form of thick widespread layers in the percolation zone, which decreases the capacity of the firn to store meltwater. The estimated total annual ice content retained in the firn in areas with positive surface mass balance west of the ice divide in Greenland reached a maximum of 74 ± 25 Gt in 2012, compared to the 1958–1999 average of 13 ± 2 Gt, while the percolation zone area more than doubled between 2003 and 2012. Increased melt and column densification resulted in surface lowering averaging −0.80 ± 0.39 m yr−1 between 1800 and 2800 m in the accumulation zone of western Greenland. Since 2007, annual melt and refreezing rates in the percolation zone at elevations below 2100 m surpass the annual snowfall from the previous year, implying that mass gain in the region is now in the form of refrozen meltwater. If current melt trends over high elevation regions continue, subsequent changes in firn structure will have implications for the hydrology of the ice sheet and related abrupt seasonal densification could become increasingly significant for altimetry-derived ice sheet mass balance estimates.

scholarly journals Application of GRACE to the assessment of model-based estimates of monthly Greenland Ice Sheet mass balance (2003–2012)

2016 ◽  
Vol 10 (5) ◽  
pp. 1965-1989 ◽  
Author(s):  
Nicole-Jeanne Schlegel ◽  
David N. Wiese ◽  
Eric Y. Larour ◽  
Michael M. Watkins ◽  
Jason E. Box ◽  
...  
Keyword(s):  
Mass Balance ◽  
Climate Models ◽  
Spatial Scales ◽  
Regional Climate ◽  
Ice Sheet ◽  
Greenland Ice Sheet ◽  
Regional Climate Models ◽  
Surface Mass ◽  
Model Based ◽  
Ice Sheet Mass Balance

Abstract. Quantifying the Greenland Ice Sheet's future contribution to sea level rise is a challenging task that requires accurate estimates of ice sheet sensitivity to climate change. Forward ice sheet models are promising tools for estimating future ice sheet behavior, yet confidence is low because evaluation of historical simulations is challenging due to the scarcity of continental-wide data for model evaluation. Recent advancements in processing of Gravity Recovery and Climate Experiment (GRACE) data using Bayesian-constrained mass concentration ("mascon") functions have led to improvements in spatial resolution and noise reduction of monthly global gravity fields. Specifically, the Jet Propulsion Laboratory's JPL RL05M GRACE mascon solution (GRACE_JPL) offers an opportunity for the assessment of model-based estimates of ice sheet mass balance (MB) at ∼ 300 km spatial scales. Here, we quantify the differences between Greenland monthly observed MB (GRACE_JPL) and that estimated by state-of-the-art, high-resolution models, with respect to GRACE_JPL and model uncertainties. To simulate the years 2003–2012, we force the Ice Sheet System Model (ISSM) with anomalies from three different surface mass balance (SMB) products derived from regional climate models. Resulting MB is compared against GRACE_JPL within individual mascons. Overall, we find agreement in the northeast and southwest where MB is assumed to be primarily controlled by SMB. In the interior, we find a discrepancy in trend, which we presume to be related to millennial-scale dynamic thickening not considered by our model. In the northwest, seasonal amplitudes agree, but modeled mass trends are muted relative to GRACE_JPL. Here, discrepancies are likely controlled by temporal variability in ice discharge and other related processes not represented by our model simulations, i.e., hydrological processes and ice–ocean interaction. In the southeast, GRACE_JPL exhibits larger seasonal amplitude than predicted by the models while simultaneously having more pronounced trends; thus, discrepancies are likely controlled by a combination of missing processes and errors in both the SMB products and ISSM. At the margins, we find evidence of consistent intra-annual variations in regional MB that deviate distinctively from the SMB annual cycle. Ultimately, these monthly-scale variations, likely associated with hydrology or ice–ocean interaction, contribute to steeper negative mass trends observed by GRACE_JPL. Thus, models should consider such processes at relatively high (monthly-to-seasonal) temporal resolutions to achieve accurate estimates of Greenland MB.

scholarly journals Constraining GRACE-derived cryosphere-attributed signal to irregularly shaped ice-covered areas

2013 ◽  
Vol 7 (4) ◽  
pp. 3417-3447 ◽  
Author(s):  
W. Colgan ◽  
S. Luthcke ◽  
W. Abdalati ◽  
M. Citterio
Keyword(s):  
Monte Carlo ◽  
Mass Loss ◽  
Mass Balance ◽  
Spherical Harmonic ◽  
Ice Sheet ◽  
Greenland Ice Sheet ◽  
Ice Caps ◽  
Ice Coverage ◽  
Ice Sheet Mass Balance ◽  
Harmonic Representation

Abstract. We use a Monte Carlo approach to invert a spherical harmonic representation of cryosphere-attributed mass change in order to infer the most likely underlying mass changes within irregularly shaped ice-covered areas at nominal 26 km resolution. By inverting a spherical harmonic representation through the incorporation of additional fractional ice coverage information, this approach seeks to eliminate signal leakage between non- and ice-covered areas. The spherical harmonic representation suggests a Greenland mass loss of 251 ± 25 Gt yr−1 over the December 2003 to December 2010 period. The inversion suggests 218 ± 20 Gt yr−1 was due to the ice sheet proper, and 34 ± 5 Gt yr−1 (or ~ 14%) was due to Greenland peripheral glaciers and ice caps (GrPGIC). This mass loss from GrPGIC exceeds that inferred from all ice masses on both Ellesmere and Devon Islands combined. This partition therefore highlights that GRACE-derived "Greenland" mass loss cannot be taken as synonymous with "Greenland ice sheet" mass loss when making comparisons with estimates of ice sheet mass balance derived from techniques that only sample the ice sheet proper.

Basin-scale partitioning of Greenland ice sheet mass balance components (2007–2011)

2015 ◽  
Vol 409 ◽  
pp. 89-95 ◽  
Author(s):  
M.L. Andersen ◽  
L. Stenseng ◽  
H. Skourup ◽  
W. Colgan ◽  
S.A. Khan ◽  
...  
Keyword(s):  
Mass Balance ◽  
Ice Sheet ◽  
Greenland Ice Sheet ◽  
Basin Scale ◽  
Ice Sheet Mass Balance

Elevation change of the Greenland Ice Sheet and its measurement with satellite radar altimetry

1995 ◽  
Vol 352 (1699) ◽  
pp. 335-346 ◽  
Keyword(s):  
Mass Balance ◽  
Total Error ◽  
Ice Sheet ◽  
Greenland Ice Sheet ◽  
Random Errors ◽  
Radar Altimetry ◽  
Spatial Coverage ◽  
Independent Observations ◽  
Satellite Radar ◽  
Satellite Radar Altimetry

Satellite radar altimetry is presently the only method that has provided the spatial coverage and density of observations needed to reduce the present uncertainty in the mass balance of the Greenland Ice Sheet and its contribution to change in eustatic sea level. The only such measurement reported, however, estimated that southern Greenland was thickening at 23±6 cm a -1 which is larger than was thought hitherto. This value is reconsidered given more recent information concerning the errors in the measurement. A survey of measurements of specific mass balance of the Greenland Ice Sheet is given, together with estimates of its sensitivity to temperature change. The expected behaviour is described of errors in the satellite position and errors in the range measurement to the ice sheet surface. The treatment of biases and the number of independent observations of random errors is described. It is found in particular that a higher degree of independence was given to the random errors than should have been the case. The total error is recalculated with this accounted for, and is found to remain dominated by the bias estimate and therefore largely unaffected by this change; the estimate is 23 ± 7 cm a -1 . It is concluded that the observation does support a recent thickening of the southern Greenland Ice Sheet.

scholarly journals Forty-six years of Greenland Ice Sheet mass balance from 1972 to 2018

2019 ◽  
Vol 116 (19) ◽  
pp. 9239-9244 ◽  
Author(s):  
Jérémie Mouginot ◽  
Eric Rignot ◽  
Anders A. Bjørk ◽  
Michiel van den Broeke ◽  
Romain Millan ◽  
...  
Keyword(s):  
Mass Loss ◽  
Mass Balance ◽  
Ice Sheet ◽  
Greenland Ice Sheet ◽  
Mass Gain ◽  
Surface Mass ◽  
Comprehensive Survey ◽  
Ice Sheet Mass Balance ◽  
Global Sea Level ◽  
Mass Discharge

We reconstruct the mass balance of the Greenland Ice Sheet using a comprehensive survey of thickness, surface elevation, velocity, and surface mass balance (SMB) of 260 glaciers from 1972 to 2018. We calculate mass discharge, D, into the ocean directly for 107 glaciers (85% of D) and indirectly for 110 glaciers (15%) using velocity-scaled reference fluxes. The decadal mass balance switched from a mass gain of +47 ± 21 Gt/y in 1972–1980 to a loss of 51 ± 17 Gt/y in 1980–1990. The mass loss increased from 41 ± 17 Gt/y in 1990–2000, to 187 ± 17 Gt/y in 2000–2010, to 286 ± 20 Gt/y in 2010–2018, or sixfold since the 1980s, or 80 ± 6 Gt/y per decade, on average. The acceleration in mass loss switched from positive in 2000–2010 to negative in 2010–2018 due to a series of cold summers, which illustrates the difficulty of extrapolating short records into longer-term trends. Cumulated since 1972, the largest contributions to global sea level rise are from northwest (4.4 ± 0.2 mm), southeast (3.0 ± 0.3 mm), and central west (2.0 ± 0.2 mm) Greenland, with a total 13.7 ± 1.1 mm for the ice sheet. The mass loss is controlled at 66 ± 8% by glacier dynamics (9.1 mm) and 34 ± 8% by SMB (4.6 mm). Even in years of high SMB, enhanced glacier discharge has remained sufficiently high above equilibrium to maintain an annual mass loss every year since 1998.

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