Decadal Mass Balance of the Greenland and Antarctic Ice Sheets from High Resolution Elevation Change Analysis of ERS-2 and Envisat Radar Altimetry Measurements

2008 ◽  
Author(s):  
Yonghong Li ◽  
Curt H. Davis
Keyword(s):  
High Resolution ◽  
Mass Balance ◽  
Ice Sheets ◽  
Elevation Change ◽  
Change Analysis ◽  
Radar Altimetry ◽  
Antarctic Ice Sheets

scholarly journals Present and future mass balance of the ice sheets simulated with GCM

1996 ◽  
Vol 23 ◽  
pp. 187-193 ◽  
Author(s):  
Atsumu Ohmura ◽  
Martin Wild ◽  
Lennart Bengtsson
Keyword(s):  
High Resolution ◽  
Mass Balance ◽  
Sea Level ◽  
Sea Water ◽  
Ice Sheets ◽  
Internal Surface ◽  
Surface Fluxes ◽  
Specific Mass ◽  
Mountain Glaciers ◽  
Equivalent Time

A high-resolution GCM ECHAM3 T106 was used to simulate the climates of the present and of the future under doubled CO2The ECHAM3 T106 was integrated for an equivalent time of 5 years (1) with the observed SST of the 1980s and (2) with the SST for the 2 × CO2climate generated from the ECHAM1 T21 coupled transient experiment. The main motivation for using the GCM to simulate the mass balance is the level of skill in simulating precipitation and accumulation recently achieved in the high-resolution GCM experiment. The ablation is computed, based on the GCM internal surface fluxes and the temperature/ablation relationship formulated on the Greenland field data. The two ice sheets show very different reactions towards doubling the CO2. As the decrease in accumulation and the increase in ablation in Greenland cause an annual mean specific mass balance of −225 mm (eq. −390 km3), the increase in accumulation and virtually non-melt conditions in Antarctica result in a mean annual specific mass balance of + 23 mm (eq. + 325 km3). The sum of the mass balance on both ice sheets is equivalent to the annual sea-level rise of 0.2 mm. This experiment shows that other mechanisms for sea-level change, such as the thermal expansion of the sea water and the melt of small mountain glaciers, will remain important in the coming century.

scholarly journals Present and future mass balance of the ice sheets simulated with GCM

1996 ◽  
Vol 23 ◽  
pp. 187-193 ◽  
Author(s):  
Atsumu Ohmura ◽  
Martin Wild ◽  
Lennart Bengtsson
Keyword(s):  
High Resolution ◽  
Mass Balance ◽  
Sea Level ◽  
Sea Water ◽  
Ice Sheets ◽  
Internal Surface ◽  
Surface Fluxes ◽  
Specific Mass ◽  
Mountain Glaciers ◽  
Equivalent Time

A high-resolution GCM ECHAM3 T106 was used to simulate the climates of the present and of the future under doubled CO2 The ECHAM3 T106 was integrated for an equivalent time of 5 years (1) with the observed SST of the 1980s and (2) with the SST for the 2 × CO2 climate generated from the ECHAM1 T21 coupled transient experiment. The main motivation for using the GCM to simulate the mass balance is the level of skill in simulating precipitation and accumulation recently achieved in the high-resolution GCM experiment. The ablation is computed, based on the GCM internal surface fluxes and the temperature/ablation relationship formulated on the Greenland field data. The two ice sheets show very different reactions towards doubling the CO2. As the decrease in accumulation and the increase in ablation in Greenland cause an annual mean specific mass balance of −225 mm (eq. −390 km3), the increase in accumulation and virtually non-melt conditions in Antarctica result in a mean annual specific mass balance of + 23 mm (eq. + 325 km3). The sum of the mass balance on both ice sheets is equivalent to the annual sea-level rise of 0.2 mm. This experiment shows that other mechanisms for sea-level change, such as the thermal expansion of the sea water and the melt of small mountain glaciers, will remain important in the coming century.

scholarly journals Forty-year Simulations of Firn Processes over the Greenland and Antarctic Ice Sheets

2020 ◽  
Author(s):  
Brooke Medley ◽  
Thomas A. Neumann ◽  
H. Jay Zwally ◽  
Benjamin E. Smith
Keyword(s):  
Mass Balance ◽  
Accumulation Rate ◽  
Ice Sheets ◽  
Ice Sheet ◽  
Greenland Ice Sheet ◽  
Surface Mass Balance ◽  
Surface Mass ◽  
Air Content ◽  
Semi Empirical ◽  
Antarctic Ice Sheets

Abstract. Conversion of altimetry-derived ice-sheet volume change to mass requires an understanding of the evolution of the combined ice and air content within the firn column. In the absence of suitable techniques to observe the changes to the firn column across the entirety of an ice sheet, the firn column processes are typically modelled. Here, we present new 40-year simulations of firn processes over the Greenland and Antarctic Ice Sheets using the Community Firn Model and atmospheric reanalysis variables. A dataset of more than 250 measured depth-density profiles from both ice sheets provides the basis of the calibration of the dry-snow densification scheme. The resulting scheme results in a reduction in the rate of densification, relative to a commonly used semi-empirical model, through a decreased dependence on the accumulation rate, a proxy for overburden stress. The modelled firn column runoff, when combined with atmospheric variables from MERRA-2, generates realistic mean integrated surface mass balance values for the Greenland (+361 Gt yr−1) and Antarctic (+2623 Gt yr−1) ice sheets when compared to published model-ensemble means. We find that seasonal volume changes associated with firn air content are approximately 3 times larger than those associated with surface mass balance; however, when averaged over multiple years, ice and air-volume fluctuations within the firn column are of comparable magnitudes. Between 1996 and 2019, the Greenland Ice Sheet lost more than 5 % of its firn air content indicating a reduction in the total meltwater retention capability. Nearly all (>98 %) of the meltwater produced over the Antarctic Ice Sheet is retained within the firn column through infiltration and refreezing.

scholarly journals Ice-sheet mass balance: assessment, attribution and prognosis

2007 ◽  
Vol 46 ◽  
pp. 1-7 ◽  
Author(s):  
Richard B. Alley ◽  
Matthew K. Spencer ◽  
Sridhar Anandakrishnan
Keyword(s):  
Mass Loss ◽  
Mass Balance ◽  
Ice Sheets ◽  
Ice Sheet ◽  
Balance Assessment ◽  
Additional Mass ◽  
Recent Warming ◽  
The Future ◽  
Ice Sheet Mass Balance ◽  
Antarctic Ice Sheets

AbstractContrary to prior expectations that warming would cause mass addition averaged over the Greenland and Antarctic ice sheets and over the next century, the ice sheets appear to be losing mass, at least partly in response to recent warming. With warming projected for the future, additional mass loss appears more likely than not.

scholarly journals Synergistic Use of Single-Pass Interferometry and Radar Altimetry to Measure Mass Loss of NEGIS Outlet Glaciers between 2011 and 2014

2020 ◽  
Vol 12 (6) ◽  
pp. 996
Author(s):  
Lukas Krieger ◽  
Undine Strößenreuther ◽  
Veit Helm ◽  
Dana Floricioiu ◽  
Martin Horwath
Keyword(s):  
Mass Loss ◽  
Mass Balance ◽  
Ice Sheets ◽  
Ice Sheet ◽  
Volume Changes ◽  
Radar Altimetry ◽  
Surface Mass ◽  
Complementary Method ◽  
Laser Altimeters ◽  
Dem Differencing

Mass balances of individual glaciers on ice sheets have been previously reported by forming a mass budget of discharged ice and modelled ice sheet surface mass balance or a complementary method which measures volume changes over the glaciated area that are subsequently converted to glacier mass change. On ice sheets, volume changes have been measured predominantly with radar and laser altimeters but InSAR DEM differencing has also been applied on smaller ice bodies. Here, we report for the first time on the synergistic use of volumetric measurements from the CryoSat-2 radar altimetry mission together with TanDEM-X DEM differencing and calculate the mass balance of the two major outlet glaciers of the Northeast Greenland Ice Stream: Zachariæ Isstrøm and Nioghalvfjerdsfjorden (79North). The glaciers lost 3.59 ± 1.15 G t a − 1 and 1.01 ± 0.95 G t a − 1 , respectively, between January 2011 and January 2014. Additionally, there has been substantial sub-aqueous mass loss on Zachariæ Isstrøm of more than 11 G t a − 1 . We attribute the mass changes on both glaciers to dynamic downwasting. The presented methodology now permits using TanDEM-X bistatic InSAR data in the context of geodetic mass balance investigations for large ice sheet outlet glaciers. In the future, this will allow monitoring the mass changes of dynamic outlet glaciers with high spatial resolution while the superior vertical accuracy of CryoSat-2 can be used for the vast accumulation zones in the ice sheet interior.

scholarly journals Heterogeneous spatial and temporal pattern of surface elevation change and mass balance of the Patagonian ice fields between 2000 and 2016

2019 ◽  
Vol 13 (9) ◽  
pp. 2511-2535 ◽  
Author(s):  
Wael Abdel Jaber ◽  
Helmut Rott ◽  
Dana Floricioiu ◽  
Jan Wuite ◽  
Nuno Miranda
Keyword(s):  
Spatial Pattern ◽  
Mass Balance ◽  
Temporal Trend ◽  
Sar Interferometry ◽  
Surface Elevation ◽  
Radar Signal ◽  
Elevation Change ◽  
Mass Losses ◽  
Digital Elevation ◽  
Surface Elevation Change

Abstract. The northern and southern Patagonian ice fields (NPI and SPI) have been subject to accelerated retreat during the last decades, with considerable variability in magnitude and timing among individual glaciers. We derive spatially detailed maps of surface elevation change (SEC) of NPI and SPI from bistatic synthetic aperture radar (SAR) interferometry data of the Shuttle Radar Topography Mission (SRTM) and TerraSAR-X add-on for Digital Elevation Measurements (TanDEM-X) for two epochs, 2000–2012 and 2012–2016, and provide data on changes in surface elevation and ice volume for the individual glaciers and the ice fields at large. We apply advanced TanDEM-X processing techniques allowing us to cover 90 % and 95 % of the area of NPI and 97 % and 98 % of SPI for the two epochs, respectively. Particular attention is paid to precisely co-registering the digital elevation models (DEMs), accounting for possible effects of radar signal penetration through backscatter analysis and correcting for seasonality biases in case of deviations in repeat DEM coverage from full annual time spans. The results show a different temporal trend between the two ice fields and reveal a heterogeneous spatial pattern of SEC and mass balance caused by different sensitivities with respect to direct climatic forcing and ice flow dynamics of individual glaciers. The estimated volume change rates for NPI are -4.26±0.20 km3 a−1 for epoch 1 and -5.60±0.74 km3 a−1 for epoch 2, while for SPI these are -14.87±0.52 km3 a−1 for epoch 1 and -11.86±1.99 km3 a−1 for epoch 2. This corresponds for both ice fields to an eustatic sea level rise of 0.048±0.002 mm a−1 for epoch 1 and 0.043±0.005 mm a−1 for epoch 2. On SPI the spatial pattern of surface elevation change is more complex than on NPI and the temporal trend is less uniform. On terminus sections of the main calving glaciers of SPI, temporal variations in flow velocities are a main factor for differences in SEC between the two epochs. Striking differences are observed even on adjoining glaciers, such as Upsala Glacier, with decreasing mass losses associated with slowdown of flow velocity, contrasting with acceleration and increase in mass losses on Viedma Glacier.

scholarly journals High Resolution Landscape Change Analysis with CORONA KH-4B Imagery. A Case Study from Iron Gates Reservoir Area

2016 ◽  
Vol 32 ◽  
pp. 200-210 ◽  
Author(s):  
Bogdan Mihai ◽  
Constantin Nistor ◽  
Liviu Toma ◽  
Ionuţ Săvulescu
Keyword(s):  
High Resolution ◽  
Landscape Change ◽  
Change Analysis ◽  
Reservoir Area
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