scholarly journals Glaciological studies on Nelson Island, South Shetland Islands, Antarctica

1995 ◽  
Vol 41 (138) ◽  
pp. 408-412 ◽  
Author(s):  
Ren Jiawen ◽  
Qin Dahe ◽  
J. R. Petit ◽  
J. Jouzel ◽  
Wang Wenti ◽  
...  
Keyword(s):  
Accumulation Rate ◽  
Local Environment ◽  
High Viscosity ◽  
Force Balance ◽  
South Shetland Islands ◽  
Balance Model ◽  
Shetland Islands ◽  
Ice Cap ◽  
Basal Sliding ◽  
Marine Air

AbstractThe ice cap on Nelson Island in the South Shetland Islands, West Antarctica, was studied between 1985 and 1989. The ice cap has an average thickness of 120 m. it is temperate, exists under the sub-Antarctic maritime climate and almost completely covers the island. Owing to intense percolation of meltwater (and, to some extent, liquid precipitation), the snow-firn layer is in the soaked facies, with a firn-ice transition at a depth of 25-26 m at the summit. A force-balance model suggests that the ice is almost linearly viscous but has a high viscosity. The model further suggests that basal sliding makes a larger contribution to the ice movement than does ice deformation. From 1970 to 1988. the average accumulation rate was 120 kg m−2a−1at the centre, and between 1985 and 1989 the equilibrium-line elevation averaged 110m a.s.l. Analysis of chemical impurities in the surface snow suggests that the precipitation source is mainly local marine air masses and that human activity has already exerted a detectable influence on the local environment.

scholarly journals Glaciological studies on Nelson Island, South Shetland Islands, Antarctica

1995 ◽  
Vol 41 (138) ◽  
pp. 408-412 ◽  
Author(s):  
Ren Jiawen ◽  
Qin Dahe ◽  
J. R. Petit ◽  
J. Jouzel ◽  
Wang Wenti ◽  
...  
Keyword(s):  
Accumulation Rate ◽  
Local Environment ◽  
High Viscosity ◽  
Force Balance ◽  
South Shetland Islands ◽  
Balance Model ◽  
Shetland Islands ◽  
Ice Cap ◽  
Basal Sliding ◽  
Marine Air

AbstractThe ice cap on Nelson Island in the South Shetland Islands, West Antarctica, was studied between 1985 and 1989. The ice cap has an average thickness of 120 m. it is temperate, exists under the sub-Antarctic maritime climate and almost completely covers the island. Owing to intense percolation of meltwater (and, to some extent, liquid precipitation), the snow-firn layer is in the soaked facies, with a firn-ice transition at a depth of 25-26 m at the summit. A force-balance model suggests that the ice is almost linearly viscous but has a high viscosity. The model further suggests that basal sliding makes a larger contribution to the ice movement than does ice deformation. From 1970 to 1988. the average accumulation rate was 120 kg m−2a−1 at the centre, and between 1985 and 1989 the equilibrium-line elevation averaged 110m a.s.l. Analysis of chemical impurities in the surface snow suggests that the precipitation source is mainly local marine air masses and that human activity has already exerted a detectable influence on the local environment.

scholarly journals Climate sensitivity of the ice cap of King George Island, South Shetland Islands, Antarctica

1996 ◽  
Vol 23 ◽  
pp. 154-159 ◽  
Author(s):  
Wouter H. Knap ◽  
Johannes Oerlemans ◽  
Martin Cabée
Keyword(s):  
Climate Change ◽  
South Shetland Islands ◽  
Balance Model ◽  
King George Island ◽  
Shetland Islands ◽  
Ice Volume ◽  
Ice Cap ◽  
Current State ◽  
Highly Sensitive ◽  
Business As Usual

A two-dimensional vertically integrated ice-flow model has been used to simulate the current state of the ice cap of King George Island, South Shetland Islands, Antarctica, as well as the sensitivity of this state to climate change. The model was forced by an energy-balance model that generates the specific mass balance from climatological input data of two research stations. It proved difficult to simulate-satisfactorily the entire geometry of the present-day ice cap. Nevertheless, it was possible to simulate a steady-state ice cap whose volume and areal extent approximate the (estimated) current situation. Several experiments have indicated that this state is highly sensitive to climate change. The model predicts that cooling by 1 K will increase the ice volume by 10% and warming by 1 K will decrease it by 36%. A 10% change in precipitation will alter the ice volume by less than 8%. Application of the IPCC-90 Business-as-Usual scenario leads to a 55% reduction in the ice volume by the year AD 2100, compared to the present-day situation. The response of the ice cap to warming is therefore totally different from the response of the main Antarctic ice sheet which is believed to gain mass by increasing temperatures.

scholarly journals Glaciological studies on the King George Island ice cap, South Shetland Islands, Antarctica

1998 ◽  
Vol 27 ◽  
pp. 105-109 ◽  
Author(s):  
Wen Jiahong ◽  
Kang Jiancheng ◽  
Han Jiankang ◽  
Xie Zichu ◽  
Liu Leibao ◽  
...  
Keyword(s):  
Accumulation Rate ◽  
Stable State ◽  
Equilibrium Line ◽  
South Shetland Islands ◽  
Mean Annual Temperature ◽  
King George Island ◽  
Equilibrium Line Altitude ◽  
Shetland Islands ◽  
Ice Cap ◽  
The Mean

The King George Island ice cap, South Shetland Islands, Antarctica, was studied between 1985 and 1992. At the steady-state equilibrium-line altitude of the ice cap, the mean annual temperature is -3.6°C, the mean summer (December-February) temperature is 0°C and annual precipitation is 800 mm w.e. Precipitation increases rapidly with elevation, and annual accumulation rate at the Main Dome summit reaches 2480 mm a−1. Between 1985 and 1991 the equilibrium-line elevation averaged 140-150 m a.s.l. The ice cap has been in an overall stable state for the past 20 years, going from a weak negative to a small positive mass imbalance as increased precipitation outweighs the effects of rising temperatures. Temperatures at the bottom of the active layer over most of the accumulation area are close to 0°C, with colder temperatures down to -1.9°C in the ablation zone. Soluble impurities in the ice cap are mainly from marine sources, while undissolved mineral material amounts to only 15-54% of the total microparticle content.

scholarly journals Climate sensitivity of the ice cap of King George Island, South Shetland Islands, Antarctica

1996 ◽  
Vol 23 ◽  
pp. 154-159 ◽  
Author(s):  
Wouter H. Knap ◽  
Johannes Oerlemans ◽  
Martin Cabée
Keyword(s):  
Climate Change ◽  
South Shetland Islands ◽  
Balance Model ◽  
King George Island ◽  
Shetland Islands ◽  
Ice Volume ◽  
Ice Cap ◽  
Current State ◽  
Highly Sensitive ◽  
Business As Usual

A two-dimensional vertically integrated ice-flow model has been used to simulate the current state of the ice cap of King George Island, South Shetland Islands, Antarctica, as well as the sensitivity of this state to climate change. The model was forced by an energy-balance model that generates the specific mass balance from climatological input data of two research stations. It proved difficult to simulate-satisfactorily the entire geometry of the present-day ice cap. Nevertheless, it was possible to simulate a steady-state ice cap whose volume and areal extent approximate the (estimated) current situation. Several experiments have indicated that this state is highly sensitive to climate change. The model predicts that cooling by 1 K will increase the ice volume by 10% and warming by 1 K will decrease it by 36%. A 10% change in precipitation will alter the ice volume by less than 8%. Application of the IPCC-90 Business-as-Usual scenario leads to a 55% reduction in the ice volume by the yearAD2100, compared to the present-day situation. The response of the ice cap to warming is therefore totally different from the response of the main Antarctic ice sheet which is believed to gain mass by increasing temperatures.

scholarly journals Multi-year analysis of distributed glacier mass balance modelling and equilibrium line altitude on King George Island, Antarctic Peninsula

2018 ◽  
Vol 12 (4) ◽  
pp. 1211-1232 ◽  
Author(s):  
Ulrike Falk ◽  
Damián A. López ◽  
Adrián Silva-Busso
Keyword(s):  
Mass Balance ◽  
Air Temperature ◽  
Surface Air Temperature ◽  
High Variability ◽  
South Shetland Islands ◽  
Glacier Mass Balance ◽  
Equilibrium Line Altitude ◽  
Potter Cove ◽  
Shetland Islands ◽  
Ice Cap

Abstract. The South Shetland Islands are located at the northern tip of the Antarctic Peninsula (AP). This region was subject to strong warming trends in the atmospheric surface layer. Surface air temperature increased about 3 K in 50 years, concurrent with retreating glacier fronts, an increase in melt areas, ice surface lowering and rapid break-up and disintegration of ice shelves. The positive trend in surface air temperature has currently come to a halt. Observed surface air temperature lapse rates show a high variability during winter months (standard deviations up to ±1.0K(100m)-1) and a distinct spatial heterogeneity reflecting the impact of synoptic weather patterns. The increased mesocyclonic activity during the wintertime over the past decades in the study area results in intensified advection of warm, moist air with high temperatures and rain and leads to melt conditions on the ice cap, fixating surface air temperatures to the melting point. Its impact on winter accumulation results in the observed negative mass balance estimates. Six years of continuous glaciological measurements on mass balance stake transects as well as 5 years of climatological data time series are presented and a spatially distributed glacier energy balance melt model adapted and run based on these multi-year data sets. The glaciological surface mass balance model is generally in good agreement with observations, except for atmospheric conditions promoting snow drift by high wind speeds, turbulence-driven snow deposition and snow layer erosion by rain. No drift in the difference between simulated mass balance and mass balance measurements can be seen over the course of the 5-year model run period. The winter accumulation does not suffice to compensate for the high variability in summer ablation. The results are analysed to assess changes in meltwater input to the coastal waters, specific glacier mass balance and the equilibrium line altitude (ELA). The Fourcade Glacier catchment drains into Potter cove, has an area of 23.6 km2 and is glacierized to 93.8 %. Annual discharge from Fourcade Glacier into Potter Cove is estimated to q¯=25±6hm3yr-1 with the standard deviation of 8 % annotating the high interannual variability. The average ELA calculated from our own glaciological observations on Fourcade Glacier over the time period 2010 to 2015 amounts to 260±20 m. Published studies suggest rather stable conditions of slightly negative glacier mass balance until the mid-1980s with an ELA of approx. 150 m. The calculated accumulation area ratio suggests dramatic changes in the future extent of the inland ice cap for the South Shetland Islands.

scholarly journals The deglaciation of Barton Peninsula (King George Island, South Shetland Islands, Antarctica) based on geomorphological evidence and lacustrine records

Polar Record ◽  
2019 ◽  
Vol 55 (3) ◽  
pp. 177-188 ◽  
Author(s):  
Marc Oliva ◽  
Dermot Antoniades ◽  
Enrique Serrano ◽  
Santiago Giralt ◽  
Emma J. Liu ◽  
...  
Keyword(s):  
Lake Sediments ◽  
Environmental Changes ◽  
Lacustrine Sediments ◽  
South Shetland Islands ◽  
King George Island ◽  
Glacial Retreat ◽  
Radiocarbon Dates ◽  
Shetland Islands ◽  
Ice Cap ◽  
Barton Peninsula

AbstractBarton Peninsula is an ice-free area located in the southwest corner of King George Island (South Shetland Islands, Antarctica). Following the Last Glacial Maximum, several geomorphological features developed in newly exposed ice-free terrain and their distribution provide insights about past environmental evolution of the area. Three moraine systems are indicative of three main glacial phases within the long-term glacial retreat, which also favoured the development of numerous lakes. Five of these lakes were cored to understand in greater detail the pattern of deglaciation through the study of lacustrine records. Radiocarbon dates from basal lacustrine sediments enabled the reconstruction of the chronology of Holocene glacial retreat. Tephra layers present in lake sediments provided additional independent age constraints on environmental changes based on geochemical and geochronological correlation with Deception Island-derived tephra. Shrinking of the Collins Glacier exposed the southern coastal fringe of Barton Peninsula at 8 cal ky BP. After a period of relative stability during the mid-Holocene, the ice cap started retreating northwards after 3.7 cal ky BP, confining some glaciers within valleys as shown by moraine systems. Lake sediments confirm a period of relative glacial stability during the last 2.4 cal ky BP.

scholarly journals Geometry and thermal regime of the King George Island ice cap, Antarctica, from GPR and GPS

2010 ◽  
Vol 51 (55) ◽  
pp. 103-109 ◽  
Author(s):  
Norbert Blindow ◽  
Sonja K. Suckro ◽  
Martin Rückamp ◽  
Matthias Braun ◽  
Marion Schindler ◽  
...  
Keyword(s):  
Water Table ◽  
Thermal Regime ◽  
South Shetland Islands ◽  
King George Island ◽  
Shetland Islands ◽  
Bed Topography ◽  
Ice Cap ◽  
Global Positioning ◽  
Ground Penetrating ◽  
The Antarctic

AbstractKing George Island is the largest of the South Shetland Islands, close to the tip of the Antarctic Peninsula. The annual mean temperature on the island has increased by 1°C during the past three decades, and the ice cap that covers the majority of the island is sensitive to climatic change. We present data from two field campaigns (1997 and 2007): 700 km of global positioning system (GPS) and ground-penetrating radar (GPR) profiles were collected on Arctowski Icefield and on the adjacent central part. The data were analysed to determine the surface and bed topography and the thermal regime of the ice. Average ice thickness is 250 m and maximum thickness is 420 m. The GPR profiles show isochrones throughout the ice cap which depict the uparching of Raymond bumps beneath or close to the ice divides. A water table from percolation of meltwater in the snowpack shows the firn-ice boundary at ∼ 3 5 m depth. The firn layer may be temperate due to the release of latent heat. In the area below 400ma.s.l., backscatter by water inclusions is abundant for ice depths below the water table. We interpret this as evidence for temperate ice. Scatter decreases significantly above 400 m. Ice temperatures below the water table in this part of the ice cap are subject to further field and modelling investigations.

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