scholarly journals Rapid retreat, acceleration and thinning of Glaciar Upsala, Southern Patagonia Icefield, initiated in 2008

2013 ◽  
Vol 54 (63) ◽  
pp. 131-138 ◽  
Author(s):  
Daiki Sakakibara ◽  
Shin Sugiyama ◽  
Takanobu Sawagaki ◽  
Sebastián Marinsek ◽  
Pedro Skvarca
Keyword(s):  
Satellite Images ◽  
Surface Elevation ◽  
Stable Phase ◽  
Tidewater Glaciers ◽  
Ice Surface ◽  
Research Activities ◽  
Front Position ◽  
Southern Patagonia ◽  
Glacier Front ◽  
Ice Velocity

AbstractThe Patagonia Icefields are characterized by a large number of outlet glaciers calving into lakes and the ocean. In contrast to the recent intensive research activities on tidewater glaciers in other regions, very few observations have been made on calving glaciers in Patagonia. We analysed satellite images of Glaciar Upsala, the third largest freshwater calving glacier in the Southern Patagonia Icefield, to investigate changes in its front position, ice velocity and surface elevation from 2000 to 2011. Our analyses revealed a clear transition from a relatively stable phase to a rapidly retreating and fast-flowing condition in 2008. The glacier front receded by 2.9 km, and the ice velocity increased by 20–50%, over the 2008–11 period. We also found that the ice surface lowered at a rate of up to 39 m a−1 from 2006 to 2010. This magnitude and the rate of changes in the glacier front position, ice velocity and surface elevation are greater than previously reported for Glaciar Upsala, and comparable to recent observations of large tidewater glaciers in Greenland. Our data illustrate details of a rapidly retreating calving glacier in Patagonia that have been scarcely reported despite their importance to the mass budget of the Patagonia Icefields.

scholarly journals Grounding line migration through the calving season at Jakobshavn Isbræ, Greenland, observed with terrestrial radar interferometry

2018 ◽  
Vol 12 (4) ◽  
pp. 1387-1400 ◽  
Author(s):  
Surui Xie ◽  
Timothy H. Dixon ◽  
Denis Voytenko ◽  
Fanghui Deng ◽  
David M. Holland
Keyword(s):  
Sea Level ◽  
Flow Line ◽  
Time Derivative ◽  
Late Summer ◽  
Early Summer ◽  
Velocity Variation ◽  
Ice Surface ◽  
Glacier Front ◽  
Ice Velocity ◽  
Calving Season

Abstract. Ice velocity variations near the terminus of Jakobshavn Isbræ, Greenland, were observed with a terrestrial radar interferometer (TRI) during three summer campaigns in 2012, 2015, and 2016. We estimate a  ∼  1 km wide floating zone near the calving front in early summer of 2015 and 2016, where ice moves in phase with ocean tides. Digital elevation models (DEMs) generated by the TRI show that the glacier front here was much thinner (within 1 km of the glacier front, average ice surface is  ∼  100 and  ∼  110 m above local sea level in 2015 and 2016, respectively) than ice upstream (average ice surface is  >  150 m above local sea level at 2–3 km to the glacier front in 2015 and 2016). However, in late summer 2012, there is no evidence of a floating ice tongue in the TRI observations. Average ice surface elevation near the glacier front was also higher,  ∼  125 m above local sea level within 1 km of the glacier front. We hypothesize that during Jakobshavn Isbræ's recent calving seasons the ice front advances  ∼  3 km from winter to spring, forming a  >  1 km long floating ice tongue. During the subsequent calving season in mid- and late summer, the glacier retreats by losing its floating portion through a sequence of calving events. By late summer, the entire glacier is likely grounded. In addition to ice velocity variation driven by tides, we also observed a velocity variation in the mélange and floating ice front that is non-parallel to long-term ice flow motion. This cross-flow-line signal is in phase with the first time derivative of tidal height and is likely associated with tidal currents or bed topography.

scholarly journals Grounding line migration through the calving season of Jakobshavn Isbræ, Greenland, observed with terrestrial radar interferometry

2018 ◽  
Author(s):  
Surui Xie ◽  
Timothy H. Dixon ◽  
Denis Voytenko ◽  
Fanghui Deng ◽  
David M. Holland
Keyword(s):  
Early Summer ◽  
Floating Zone ◽  
Ocean Tides ◽  
Ice Surface ◽  
Digital Elevation ◽  
Grounding Line ◽  
Glacier Front ◽  
Ice Velocity ◽  
Velocity Variations ◽  
Calving Season

Abstract. Ice velocity variations near the terminus of Jakobshavn Isbræ, Greenland were observed with a terrestrial radar interferometer (TRI) during three summer campaigns in 2012, 2015, and 2016. Ice velocity variations appear to be largely modulated by ocean tides. We estimate a ∼ 1 km wide floating zone near the calving front in early summer of 2015 and 2016, where ice moves in phase with ocean tides. Digital Elevation Models (DEMs) generated by the TRI show that the glacier front here is thin (ice surface is  140 m above local sea level within a very short distance (

scholarly journals Changes in the Ice-Front Position and Surface Elevation of Glaciar Pío XI, an Advancing Calving Glacier in the Southern Patagonia Icefield, From 2000–2018

2021 ◽  
Vol 8 ◽  
Author(s):  
Shuntaro Hata ◽  
Shin Sugiyama
Keyword(s):  
Surface Elevation ◽  
Glacier Surface ◽  
Outlet Glacier ◽  
Ablation Area ◽  
Total Mass Loss ◽  
Period 2 ◽  
Front Position ◽  
Compressive Flow ◽  
Southern Patagonia ◽  
Mass Increase

Glaciar Pío XI has advanced and thickened over the past several decades in contrast to the generally retreating and thinning trends seen in other glaciers in the Southern Patagonia Icefield (SPI). To quantify recent changes in ice-front positions and glacier surface elevation over the ablation area of Glaciar Pío XI, we analyzed satellite data acquired from 2000 to 2018. Two major glacier termini, and most of the small outlet glaciers, showed advancing trends, including the largest advance (1,400 m), observed at the southern terminus during the study period. Surface elevation increased by 37.3 ± 0.4 m as a mean over the study area, and the rate of the increase accelerated by 135 ± 10% from Period 1 (2000–2007) to Period 2 (2007–2017/18). Elevation change during Period 1 was only slightly positive except for extraordinary thickening (∼20 m a−1) observed near the southern terminus and one of the outlet glacier fronts, whereas significant thickening (∼2.7 m a−1) occurred over the entire ablation area during Period 2. Satellite imagery showed an emergence of sedimentary mounds in front of the southern terminus, suggesting that reduction in frontal ablation and increasingly compressive flow regime are the main drivers of the recent rapid thickening and advance. Most likely, the influence of the sediment deposition on the southern terminus subsequently propagated to the northern terminus and upper reaches of the glacier. The rate of ice mass increase during the study period was 0.48 ± 0.03 Gt a−1, which corresponds to 4% of the total mass loss from the SPI from 2000 to 2015/16.

scholarly journals A two-dimensional glacier–fjord coupled model applied to estimate submarine melt rates and front position changes of Hansbreen, Svalbard

2018 ◽  
Vol 64 (247) ◽  
pp. 745-758 ◽  
Author(s):  
E. DE ANDRÉS ◽  
J. OTERO ◽  
F. NAVARRO ◽  
A. PROMIŃSKA ◽  
J. LAPAZARAN ◽  
...  
Keyword(s):  
Coupled Model ◽  
Small Scale ◽  
Two Dimensional ◽  
Time Step ◽  
Software Packages ◽  
Front Position ◽  
Circulation Patterns ◽  
Glacier Front ◽  
Order Of Magnitude ◽  
Frontal Ablation

ABSTRACTWe have developed a two-dimensional coupled glacier–fjord model, which runs automatically using Elmer/Ice and MITgcm software packages, to investigate the magnitude of submarine melting along a vertical glacier front and its potential influence on glacier calving and front position changes. We apply this model to simulate the Hansbreen glacier–Hansbukta proglacial–fjord system, Southwestern Svalbard, during the summer of 2010. The limited size of this system allows us to resolve some of the small-scale processes occurring at the ice–ocean interface in the fjord model, using a 0.5 s time step and a 1 m grid resolution near the glacier front. We use a rich set of field data spanning the period April–August 2010 to constrain, calibrate and validate the model. We adjust circulation patterns in the fjord by tuning subglacial discharge inputs that best match observed temperature while maintaining a compromise with observed salinity, suggesting a convectively driven circulation in Hansbukta. The results of our model simulations suggest that both submarine melting and crevasse hydrofracturing exert important controls on seasonal frontal ablation, with submarine melting alone not being sufficient for reproducing the observed patterns of seasonal retreat. Both submarine melt and calving rates accumulated along the entire simulation period are of the same order of magnitude, ~100 m. The model results also indicate that changes in submarine melting lag meltwater production by 4–5 weeks, which suggests that it may take up to a month for meltwater to traverse the englacial and subglacial drainage network.

scholarly journals Recent behaviour of Glaciar Upsala, a fast-flowing calving glacier in Lago Argentino, southern Patagonia

2003 ◽  
Vol 36 ◽  
pp. 184-188 ◽  
Author(s):  
Pedro Skvarca ◽  
Bruce Raup ◽  
Hernan de Angelis
Keyword(s):  
Cross Correlation ◽  
High Spatial Resolution ◽  
Winter Period ◽  
Optical Images ◽  
Southern Patagonia ◽  
Glacier Front ◽  
Calving Rate ◽  
Depth Relationship ◽  
Surface Ice ◽  
First Time

AbstractSequential optical images of high spatial resolution were used for the first time to derive surface ice velocities of Glaciar Upsala, a fast-moving fresh-water calving glacier in southern Patagonia. Cross-correlation methods applied to four Landsat ETM+ images acquired in 2000–01 yielded average velocities of around 1600 m a−1, similar to values measured in the field in November 1993. The derived velocities show almost no seasonal variation for the analyzed calving termini. During the period of satellite coverage, clear readvances were detected in the autumn–winter period, followed by recessions during summers. Between 24 April 1999 and 14 October 2001, the glacier front has been fluctuating seasonally within about 400 m, in contrast to the previous dramatic recession. During the last 2.5 years, Glaciar Upsala west terminus had a net advance of around 300 m. In addition, the available satellite images allowed us to determine recent calving speeds and confirm the improved calving-rate/water-depth relationship, recently proposed by incorporating new data from Patagonian glaciers.

scholarly journals The propagation of a surge front on Bering Glacier, Alaska, 2001–2011

2013 ◽  
Vol 54 (63) ◽  
pp. 221-228 ◽  
Author(s):  
James Turrin ◽  
Richard R. Forster ◽  
Chris Larsen ◽  
Jeanne Sauber
Keyword(s):  
Feature Tracking ◽  
Average Rate ◽  
Surface Velocity ◽  
Ablation Zone ◽  
Ice Surface ◽  
Glacier Terminus ◽  
Bering Glacier ◽  
Landsat 7 ◽  
Ice Velocity ◽  
Recent Activity

AbstractBering Glacier, Alaska, USA, has a ∼20 year surge cycle, with its most recent surge reaching the terminus in 2011. To study this most recent activity a time series of ice velocity maps was produced by applying optical feature-tracking methods to Landsat-7 ETM+ imagery spanning 2001-11. The velocity maps show a yearly increase in ice surface velocity associated with the down-glacier movement of a surge front. In 2008/09 the maximum ice surface velocity was 1.5 ±0.017 km a-1 in the mid-ablation zone, which decreased to 1.2 ±0.015 km a-1 in 2009/10 in the lower ablation zone, and then increased to nearly 4.4 ± 0.03 km a-1 in summer 2011 when the surge front reached the glacier terminus. The surge front propagated down-glacier as a kinematic wave at an average rate of 4.4 ±2.0 km a-1 between September 2002 and April 2009, then accelerated to 13.9 ± 2.0 km a-1 as it entered the piedmont lobe between April 2009 and September 2010. The wave seems to have initiated near the confluence of Bering Glacier and Bagley Ice Valley as early as 2001, and the surge was triggered in 2008 further down-glacier in the mid-ablation zone after the wave passed an ice reservoir area.

Five decades of changes in the glaciers on the Friendship Peak in the Altai Mountains, China: Changes in area and ice surface elevation

2015 ◽  
Vol 116 ◽  
pp. 24-31 ◽  
Author(s):  
Puyu Wang ◽  
Zhongqin Li ◽  
Shufei Luo ◽  
Jinzhong Bai ◽  
Baojuan Huai ◽  
...  
Keyword(s):  
Surface Elevation ◽  
Altai Mountains ◽  
Ice Surface

Ice Surface Elevation of Central Marie Byrd Land

1962 ◽  
Vol 4 (31) ◽  
pp. 121-123 ◽  
Author(s):  
J. C. Behrendt ◽  
R. J. Wold ◽  
F. L. Dowling
Keyword(s):  
Surface Elevation ◽  
Ice Shelf ◽  
Ice Surface ◽  
Altimetric Data ◽  
The Antarctic

An ice surface map of central Marie Byrd Land has been compiled from aero-altimetric data taken on 14,000 km. of flight lines during the Antarctic summer of 1960–61 using standard aircraft equipment. A large depression sloping down towards the Filchner Ice Shelf was determined and earlier known features in the area are shown in greater detail.

scholarly journals Geostatistical methods for mapping Antarctic ice surfaces at continental and regional scales

2000 ◽  
Vol 30 ◽  
pp. 76-82 ◽  
Author(s):  
Ute Christina Herzfeld ◽  
Ralf Stosius ◽  
Marcus Schneider
Keyword(s):  
Surface Elevation ◽  
Altimeter Data ◽  
Radar Altimeter ◽  
Sea Level Changes ◽  
Ice Streams ◽  
Geostatistical Methods ◽  
Ice Surface ◽  
Geophysical Study ◽  
Satellite Radar ◽  
The Antarctic

AbstractThe Antarctic ice sheet plays a major role in the global system and the large ice streams discharging into the circumpolar sea represent its gateways to the world’s oceans. Satellite radar-altimeter data provide an opportunity for mapping surface elevation at kilometer resolution with meter accuracy. Geostatistical methods have been developed to accomplish this. We distinguish two goals in mapping the Antarctic ice surface: (a) construction of a continent-wide atlas of maps and digital terrain models, and (b) calculation of maps and models suitable for the study of individual glaciers, ice streams and ice shelves. The atlases consist of accurate maps of ice-surface elevation compiled from Seasat, Geosat and ERS-1 altimeter data, covering all of Antarctica surveyed by Geosat (to 72.1° S) and by ERS-1 (to 81.5° S). With a 3 km grid they are the highest-resolution maps available today with continent-wide coverage. The resolution permits geophysical study and facilitates monitoring of changes in ice-surface elevation and changes in flux across the ice-ocean boundary, which is essential for monitoring sea-level changes.

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