Regional modeling of surface mass balance on the Cook Ice Cap, Kerguelen Islands ($$49^{\circ }\mathrm{S}$$, $$69^{\circ }\mathrm{E}$$)

ABSTRACTMost Icelandic glaciers show high-accumulation rates during winter and strong surface melting during summer. Although it is difficult to establish and maintain mass-balance programs on these glaciers, mass-balance series do exist for several of the ice caps (Björnsson and others, 2013). We make use of the frequent volcanic eruptions in Iceland, which cause widespread internal tephra layers in the ice caps, to reconstruct the surface mass balance (SMB) in the ablation zone. This method requires information about surface geometry and ice velocity, derived from remote-sensing information. In addition, the emergence angle of the tephra layer needs to be known. As a proof-of-concept, we utilize a prominent tephra layer of the Mýrdalsjökull Ice Cap to infer local SMB estimates in the ablation area back to 1988. Using tephra-layer outcrop locations across the glacier at different points in time it is possible to determine local mass changes (loss and redistribution) for a large part of the ablation zone, without the use of historic elevation models, which often are not available.

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A regression model for the mass-balance distribution of the Vatnajökull ice cap, Iceland

Annals of Glaciology ◽

10.3189/172756403781815447 ◽

2003 ◽

Vol 37 ◽

pp. 189-193 ◽

Cited By ~ 10

Author(s):

Guðefinna Aðalgeirsdóttir ◽

G. Hilmar Gudmundsson ◽

Helgi Björnsson

Keyword(s):

Linear Regression ◽

Regression Model ◽

Mass Balance ◽

Surface Mass Balance ◽

Negative Mass ◽

Equilibrium Line Altitude ◽

Surface Mass ◽

Ice Cap ◽

Maximum Value ◽

Slope Direction

AbstractA non-linear regression model describing the mass-balance distribution of the whole Vatnajökull ice cap, Iceland, for the years 1992–2000 is presented. All available data from some 40 locations over this 9 year period were used to determine the parameters of the model. The regression model uses six adjustable parameters which all have a clear physical interpretation. They are the slope, direction and the height of the equilibrium-line altitude (ELA) plane, two altitude mass-balance gradients, and a maximum value of the surface mass balance. It is found that the temporal variation of the observed mass-balance distribution can be accurately described through annual shifts of the ELA. Annual shifts in ELA are on the order of 100 m, which is of the same magnitude as the change expected to be caused by the climate variation predicted during the next decades. A slight trend towards a more negative mass balance is detected during this 9 year period.

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Surface velocity and mass balance of Livingston Island ice cap, Antarctica

The Cryosphere ◽

10.5194/tc-8-1807-2014 ◽

2014 ◽

Vol 8 (5) ◽

pp. 1807-1823 ◽

Cited By ~ 28

Author(s):

B. Osmanoglu ◽

F. J. Navarro ◽

R. Hock ◽

M. Braun ◽

M. I. Corcuera

Keyword(s):

Mass Balance ◽

Surface Velocity ◽

South Shetland Islands ◽

Surface Mass Balance ◽

Surface Mass ◽

Ice Caps ◽

Ice Cap ◽

Livingston Island ◽

Flux Gate ◽

Frontal Ablation

Abstract. The mass budget of the ice caps surrounding the Antarctica Peninsula and, in particular, the partitioning of its main components are poorly known. Here we approximate frontal ablation (i.e. the sum of mass losses by calving and submarine melt) and surface mass balance of the ice cap of Livingston Island, the second largest island in the South Shetland Islands archipelago, and analyse variations in surface velocity for the period 2007–2011. Velocities are obtained from feature tracking using 25 PALSAR-1 images, and used in conjunction with estimates of glacier ice thicknesses inferred from principles of glacier dynamics and ground-penetrating radar observations to estimate frontal ablation rates by a flux-gate approach. Glacier-wide surface mass-balance rates are approximated from in situ observations on two glaciers of the ice cap. Within the limitations of the large uncertainties mostly due to unknown ice thicknesses at the flux gates, we find that frontal ablation (−509 ± 263 Mt yr−1, equivalent to −0.73 ± 0.38 m w.e. yr−1 over the ice cap area of 697 km2) and surface ablation (−0.73 ± 0.10 m w.e. yr−1) contribute similar shares to total ablation (−1.46 ± 0.39 m w.e. yr−1). Total mass change (δM = −0.67 &plusmn 0.40 m w.e. yr−1) is negative despite a slightly positive surface mass balance (0.06 ± 0.14 m w.e. yr−1). We find large interannual and, for some basins, pronounced seasonal variations in surface velocities at the flux gates, with higher velocities in summer than in winter. Associated variations in frontal ablation (of ~237 Mt yr−1; −0.34 m w.e. yr−1) highlight the importance of taking into account the seasonality in ice velocities when computing frontal ablation with a flux-gate approach.

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Two-dimensional prognostic experiments for fast-flowing ice streams from the Academy of Sciences Ice Cap

Earth System Dynamics ◽

10.5194/esd-8-283-2017 ◽

2017 ◽

Vol 8 (2) ◽

pp. 283-294

Author(s):

Yuri V. Konovalov ◽

Oleg V. Nagornov

Keyword(s):

Mass Balance ◽

Flow Line ◽

Surface Mass Balance ◽

Ice Streams ◽

Surface Mass ◽

Ice Cap ◽

Ice Surface ◽

Ice Surface Temperature ◽

Severnaya Zemlya ◽

Academy Of Sciences

Abstract. Prognostic experiments for fast-flowing ice streams on the southern side of the Academy of Sciences Ice Cap on Komsomolets Island, Severnaya Zemlya archipelago, were undertaken in this study. The experiments were based on inversions of basal friction coefficients using a two-dimensional flow-line thermocoupled model and Tikhonov's regularization method. The modeled ice temperature distributions in the cross sections were obtained using ice surface temperature histories that were inverted previously from borehole temperature profiles derived at the summit of the Academy of Sciences Ice Cap and the elevational gradient of ice surface temperature changes (about 6.5 °C km−1). Input data included interferometric synthetic aperture radar (InSAR) ice surface velocities, ice surface elevations, and ice thicknesses obtained from airborne measurements, while the surface mass balance was adopted from previous investigations for the implementation of both the forward and inverse problems. The prognostic experiments revealed that both ice mass and ice stream extent declined for the reference time-independent surface mass balance. Specifically, the grounding line retreated: (a) along the B–B′ flow line from ∼  40 to ∼  30 km (the distance from the summit), (b) along the C–C′ flow line from ∼  43 to ∼  37 km, and (c) along the D–D′ flow line from ∼  41 to ∼  32 km, when considering a time period of 500 years and assuming a time-independent surface mass balance. Ice flow velocities in the ice streams decreased with time and this trend resulted in the overall decline of the outgoing ice flux. Generally, the modeled glacial evolution was in agreement with observations of deglaciation of the Severnaya Zemlya archipelago.

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Volume changes of Vatnajökull ice cap, Iceland, due to surface mass balance, ice flow, and subglacial melting at geothermal areas

Geophysical Research Letters ◽

10.1029/2004gl021615 ◽

2005 ◽

Vol 32 (5) ◽

Cited By ~ 24

Author(s):

Eyjólfur Magnússon

Keyword(s):

Mass Balance ◽

Surface Mass Balance ◽

Volume Changes ◽

Ice Flow ◽

Surface Mass ◽

Ice Cap

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Two-dimensional prognostic experiments for fast-flowing ice streams from the Academy of Sciences Ice Cap: future modeled histories obtained for the reference surface mass balance

Earth System Dynamics Discussions ◽

10.5194/esdd-6-2211-2015 ◽

2015 ◽

Vol 6 (2) ◽

pp. 2211-2242 ◽

Cited By ~ 1

Author(s):

Y. V. Konovalov ◽

O. V. Nagornov

Keyword(s):

Mass Balance ◽

Flow Line ◽

The Arctic ◽

Surface Mass Balance ◽

Two Dimensional ◽

Ice Streams ◽

Surface Mass ◽

Ice Cap ◽

Ice Surface ◽

Academy Of Sciences

Abstract. The prognostic experiments for fast-flowing ice streams on the southern side of the Academy of Sciences Ice Cap in the Komsomolets Island, Severnaya Zemlya archipelago, are implemented in this study. These experiments are based on inversions of basal friction coefficients using a two-dimensional flow-line thermo-coupled model and the Tikhonov's regularization method. The modeled ice temperature distributions in the cross-sections were obtained using the ice surface temperature histories that were inverted previously from the borehole temperature profiles derived at the Academy of Sciences Ice Cap. Input data included InSAR ice surface velocities, ice surface elevations, and ice thicknesses obtained from airborne measurements and the surface mass balance, were adopted from the prior investigations for the implementation of both the forward and inverse problems. The prognostic experiments reveal that both ice mass and ice stream extents decline for the reference time-independent surface mass balance. Specifically, the grounding line retreats (a) along the B–B' flow line from ~ 40 to ~ 30 km (the distance from the summit), (b) along the C–C' flow line from ~ 43 to ~ 37 km, and (c) along the D–D' flow line from ~ 41 to ~ 32 km considering a time period of 500 years and assuming time-independent surface mass balance. Ice flow velocities in the ice streams decrease with time and this trend results in the overall decline of the outgoing ice flux. Generally, the modeled histories are in agreement with observations of sea ice extent and thickness indicating a continual ice decline in the Arctic.

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Surface mass balance, ice velocity and near-surface ice temperature on Qaanaaq Ice Cap, northwestern Greenland, from 2012 to 2016

Annals of Glaciology ◽

10.1017/aog.2017.7 ◽

2017 ◽

Vol 58 (75pt2) ◽

pp. 181-192 ◽

Cited By ~ 8

Author(s):

Shun Tsutaki ◽

Shin Sugiyama ◽

Daiki Sakakibara ◽

Teruo Aoki ◽

Masashi Niwano

Keyword(s):

Mass Balance ◽

Snow Accumulation ◽

Surface Mass Balance ◽

Outlet Glacier ◽

Near Surface ◽

Surface Mass ◽

Ice Cap ◽

In Situ Data ◽

Ice Velocity ◽

Surface Ice

ABSTRACT To better understand the processes controlling recent mass loss of peripheral glaciers and ice caps in northwestern Greenland, we measured surface mass balance (SMB), ice velocity and near-surface ice temperature on Qaanaaq Ice Cap in the summers of 2012–16. The measurements were performed along a survey route spanning the terminus of an outlet glacier to the upper reaches (243–968 m a.s.l.). The ice-cap-wide SMB ranged from −1.10 ± 0.29 to −0.13 ± 0.26 m w.e. a−1 for the years from 2012/13 to 2015/16. Mass balance showed substantially large fluctuations over the study period under the influence of summer temperature and snow accumulation. Ice velocity showed seasonal speedup only in the summer of 2012, suggesting an extraordinary amount of meltwater penetrated to the bed and enhanced basal ice motion. Ice temperature at a depth of 13 m was −8.0°C at 944 m a.s.l., which was 2.5°C warmer than that at 243 m a.s.l., suggesting that ice temperature in the upper reaches was elevated by refreezing and percolation of meltwater. Our study provided in situ data from a relatively unstudied region in Greenland, and demonstrated the importance of continued monitoring of these processes for longer timespans in the future.

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Non-surface mass balance of glaciers in Iceland

Journal of Glaciology ◽

10.1017/jog.2020.37 ◽

2020 ◽

Vol 66 (258) ◽

pp. 685-697 ◽

Cited By ~ 1

Author(s):

Tómas Jóhannesson ◽

Bolli Pálmason ◽

Árni Hjartarson ◽

Alexander H. Jarosch ◽

Eyjólfur Magnússon ◽

...

Keyword(s):

Energy Dissipation ◽

Mass Balance ◽

Volcanic Eruptions ◽

Surface Mass Balance ◽

Geothermal Heat ◽

Surface Mass ◽

Average Mass ◽

Ice Cap ◽

Geothermal Activity ◽

Basal Melting

AbstractNon-surface mass balance is non-negligible for glaciers in Iceland. Several Icelandic glaciers are in the neo-volcanic zone where a combination of geothermal activity, volcanic eruptions and geothermal heat flux much higher than the global average lead to basal melting close to 150 mm w.e. a−1 for the Mýrdalsjökull ice cap and 75 mm w.e. a−1 for the largest ice cap, Vatnajökull. Energy dissipation in the flow of water and ice is also rather large for the high-precipitation, temperate glaciers of Iceland resulting in internal and basal melting of 20–150 mm w.e. a−1. The total non-surface melting of glaciers in Iceland in 1995–2019 was 45–375 mm w.e. a−1 on average for the main ice caps, and was largest for Mýrdalsjökull, the south side of Vatnajökull and Eyjafjallajökull. Geothermal melting, volcanic eruptions and the energy dissipation in the flow of water and ice, as well as calving, all contribute, and thus these components should be considered in mass-balance studies. For comparison, the average mass balance of glaciers in Iceland since 1995 is −500 to −1500 mm w.e. a−1. The non-surface mass balance corresponds to a total runoff contribution of 2.1 km3 a−1 of water from Iceland.

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Validation of the RACMO2.3 surface mass-balance model over northwest Devon Ice Cap, Nunavut

10.4095/308355 ◽

2018 ◽

Author(s):

D O Burgess

Keyword(s):

Mass Balance ◽

Balance Model ◽

Surface Mass Balance ◽

Mass Balance Model ◽

Surface Mass ◽

Ice Cap ◽

Devon Ice Cap

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The importance of accurate glacier albedo for estimates of surface mass balance on Vatnajökull: Evaluating the surface energy budget in a Regional Climate Model with automatic weather station observations

10.5194/tc-2017-14 ◽

2017 ◽

Cited By ~ 1

Author(s):

Louise Steffensen Schmidt ◽

Guðfinna Aðalgeirsdóttir ◽

Sverrir Guðmundsson ◽

Peter L. Langen ◽

Finnur Pálsson ◽

...

Keyword(s):

Regional Climate Model ◽

Mass Balance ◽

Climate Model ◽

Regional Climate ◽

Volcanic Eruptions ◽

Dust Storms ◽

Surface Energy Budget ◽

Surface Mass Balance ◽

Surface Mass ◽

Ice Cap

Abstract. A simulation of the surface climate of Vatnajökull ice cap, Iceland, made with the Regional Climate Model HIRHAM5 for the period 1980–2014, is used to estimate the evolution of the glacier mass balance. A new snow albedo parametrization is used for the simulation that describes the albedo with an exponential decay with time and is surface temperature dependant. The albedo scheme utilizes a new background map of the ice albedo created from observed MODIS data. The simulation is evaluated against observed daily values of weather parameters from five Automatic Weather Stations (AWSs) from 2001–2014, as well as in situ mass balance measurements from 1994–2014. The model simulates the observed parameters well at the station sites, albeit with a general underestimation of the net radiation. This is due to an underestimation of the incoming radiation and a general overestimation of the albedo. The average modelled albedo is overestimated in the ablation zone, which we attribute to an overestimation of the thickness of the snow layer and not taking dirt and volcanic ash deposition during dust storms and volcanic eruptions into account. A comparison with the specific summer, winter, and net mass balance for all of Vatnajökull from 1994–2014 shows a good overall fit during the summer, with the model underestimating the balance by only 0.04 m w.eq. on average, but a too large winter balance due to an overestimation of the precipitation at the highest areas of the ice cap. The average overestimation of the winter balance is 0.5 m w.eq., but a simple correction of the accumulation at the highest points of the glacier reduces this to 0.15 m w.eq. The model captures the evolution of the specific mass balance well, for example capturing a shift in the balance in the mid-1990s, which gives us confidence in the results for the entire model run. The model is therefore used to provide an estimate of the evolution of the specific surface mass balance of Vatnajökull from 1981, and we show the importance of bare glacier ice albedo to modelled mass balance and that processes not currently accounted for in RCMs, such as dust storms, are an important source of uncertainty in estimates of snow melt rate.

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