scholarly journals First Glaciological Studies on the James Ross Island Ice Cap, Antarctic Peninsula

1981 ◽  
Vol 27 (97) ◽  
pp. 371-379 ◽  
Author(s):  
A. J. Aristarain ◽  
R. Delmas
Keyword(s):  
Antarctic Peninsula ◽  
Accumulation Rate ◽  
Snow Accumulation ◽  
Sea Salt ◽  
Deuterium Content ◽  
Western Coast ◽  
Conductivity Measurements ◽  
Ice Cap ◽  
Climatic Regime ◽  
James Ross Island

AbstractA 10 m deep core and a 2 m pit were achieved in December 1977 on the ice cap of James Ross Island (Antarctic Peninsula) 3 km westward of the main dome at an altitude of 1 500 m. The 10 m temperature was −14.2°C. The core was cut into 106 samples which have been used for density, total β radioactivity, electroconductivity, and deuterium-content measurements. The age at the bottom of the bore hole has been estimated to be 1 965±1 year and a mean annual snow accumulation rate 37.7±3.0 g cm−2a−1is calculated over the last 13 years. By comparing our results with those obtained in other areas of the Peninsula, the climate of the upper part of James Ross Island seems to follow the climatic regime of the western coast. A preliminary chemical analysis of the pit samples leads us to conclude that the snow impurities are mainly sea-salt derived. The conductivity measurements show a clearly defined peak at the end of 1967 which could be linked with the volcanic eruption of the Deception Island volcano in December 1967. The interest of the studied location is discussed in view of further more extended glaciological investigations and particularly a possible coring to the bottom.

scholarly journals First Glaciological Studies on the James Ross Island Ice Cap, Antarctic Peninsula

1981 ◽  
Vol 27 (97) ◽  
pp. 371-379 ◽  
Author(s):  
A. J. Aristarain ◽  
R. Delmas
Keyword(s):  
Antarctic Peninsula ◽  
Accumulation Rate ◽  
Snow Accumulation ◽  
Sea Salt ◽  
Deuterium Content ◽  
Western Coast ◽  
Conductivity Measurements ◽  
Ice Cap ◽  
Climatic Regime ◽  
James Ross Island

AbstractA 10 m deep core and a 2 m pit were achieved in December 1977 on the ice cap of James Ross Island (Antarctic Peninsula) 3 km westward of the main dome at an altitude of 1 500 m. The 10 m temperature was −14.2°C. The core was cut into 106 samples which have been used for density, total β radioactivity, electroconductivity, and deuterium-content measurements. The age at the bottom of the bore hole has been estimated to be 1 965±1 year and a mean annual snow accumulation rate 37.7±3.0 g cm−2 a−1 is calculated over the last 13 years. By comparing our results with those obtained in other areas of the Peninsula, the climate of the upper part of James Ross Island seems to follow the climatic regime of the western coast. A preliminary chemical analysis of the pit samples leads us to conclude that the snow impurities are mainly sea-salt derived. The conductivity measurements show a clearly defined peak at the end of 1967 which could be linked with the volcanic eruption of the Deception Island volcano in December 1967. The interest of the studied location is discussed in view of further more extended glaciological investigations and particularly a possible coring to the bottom.

scholarly journals Climatic and Chemical Studies in James Ross Island Snow (Antarctic Peninsula) (Abstract only)

1982 ◽  
Vol 3 ◽  
pp. 347-347
Author(s):  
A Aristarain ◽  
M Briat ◽  
R Delmas ◽  
M Pourchet ◽  
J Jouzel
Keyword(s):  
Antarctic Peninsula ◽  
Seasonal Variations ◽  
Ice Core ◽  
Sea Salt ◽  
Eastern Coast ◽  
Mean Annual Temperature ◽  
Ice Cap ◽  
James Ross Island ◽  
The Mean ◽  
The Antarctic

James Ross Island (mean diameter 50 km) is located near the north-eastern coast of the Antarctic Peninsula. An ice cap, covering nearly the entire island, rises to a height of ~1 600 m. Three summer expeditions with glaciological purposes were recently achieved on this ice cap by the Instituto Antártico Argentino, two of them with the scientific participation of the Laboratoire de Glaciologie et Geophysique de I'Environnement, Grenoble.We present results of climatic and chemical investigations performed on recent snow layers dating back about 25 a. The studied samples were collected at different sites on the upper part of the ice dome. Detailed measurements (deuterium, oxygen 18 and total β activity) were performed on more than 1000 selected samples. The relationship between stable isotope and mean annual temperature fits very well with the one previously obtained in the Antarctic Peninsula.An ice core 22 m deep drilled on Dome Dalinqer (elevation 1600 m, mean annual temperature -15˚C) showed well-preserved seasonal variations in deuterium all along the profile, thus providing a yearly dating of the samples which was confirmed by β activity reference levels. The mean annual accumulation thus deduced is 500 kg m−2 between 1955 and 1979, with values significantly lower (30%) in the 1955–65 decade than in 1965–79. The same trend earlier observed in east and central parts of Antarctica thus appears to have a very large geographical extent.This well-dated core allows us to undertake a year-to-year comparison between isotopic and climatological data over the 1953–78 period. The mean annual values of the deuterium content are well correlated with the average surface temperature taken over the whole Antarctic Peninsula (δD = (3.4±2.0)T - (98±32))These data and the experimentally derived δD/δ180 relationship obtained on James Ross Island allow us to deduce a δ180 temperature gradient of 0.44‰°C−1. This low value is discussed in view of a new isotopic model taking into account the partial removal of precipitation and the possible variation of the oceanic source. James Ross Island thus appears suitable as a potential site for reconstructing past climatic changes of the Antarctic Peninsula beyond existing data.Contamination-free techniques were used for sampling and analysing the snow samples. Na, K, Ca, and Al (by atomic absorption), H+ (by titrimetric measurements), SO42- and NO3− (by ion chromatography), and conductivity were determined on more than 100 samples collected in a 4.3 m deep pit. Some of these parameters were also measured on ice-core samples or additional pit samples.Snow impurities are contributed by different aerosol sources: sea salt, continental particles and the small-size particles produced by the conversion of various atmospheric gases. The relative importance of these sources has been estimated.James Ross snow was found always to be slightly acid (1 to 10 μEquiv. l−1 of H+, mainly as sulphuric acid). Nitrate concentrations are much smaller (0.4 μEquiv. l−1). Strong seasonal variations are observed for H2SO4 deposition, probably in relation to its formation in the Antarctic atmosphere.Sea-salt deposition exhibits also seasonal variations which can be correlated with storm frequency in the Weddell Sea area. The continental aerosol contribution is weak as indicated by very low Al values.The influence of Deception Island volcanism on the regional aerosol chemistry is examined. A marked increase of snow acidity was detected after the 1967 eruption of this volcano, but no ash layers were observed.The strong variations of the conductivity of melt water are interpreted: it is shown that this parameter is not representative of the extent of sea ice

scholarly journals Climatic and Chemical Studies in James Ross Island Snow (Antarctic Peninsula) (Abstract only)

1982 ◽  
Vol 3 ◽  
pp. 347
Author(s):  
A Aristarain ◽  
M Briat ◽  
R Delmas ◽  
M Pourchet ◽  
J Jouzel
Keyword(s):  
Antarctic Peninsula ◽  
Seasonal Variations ◽  
Ice Core ◽  
Sea Salt ◽  
Eastern Coast ◽  
Mean Annual Temperature ◽  
Ice Cap ◽  
James Ross Island ◽  
The Mean ◽  
The Antarctic

James Ross Island (mean diameter 50 km) is located near the north-eastern coast of the Antarctic Peninsula. An ice cap, covering nearly the entire island, rises to a height of ~1 600 m. Three summer expeditions with glaciological purposes were recently achieved on this ice cap by the Instituto Antártico Argentino, two of them with the scientific participation of the Laboratoire de Glaciologie et Geophysique de I'Environnement, Grenoble. We present results of climatic and chemical investigations performed on recent snow layers dating back about 25 a. The studied samples were collected at different sites on the upper part of the ice dome. Detailed measurements (deuterium, oxygen 18 and total β activity) were performed on more than 1000 selected samples. The relationship between stable isotope and mean annual temperature fits very well with the one previously obtained in the Antarctic Peninsula. An ice core 22 m deep drilled on Dome Dalinqer (elevation 1600 m, mean annual temperature -15˚C) showed well-preserved seasonal variations in deuterium all along the profile, thus providing a yearly dating of the samples which was confirmed by β activity reference levels. The mean annual accumulation thus deduced is 500 kg m−2 between 1955 and 1979, with values significantly lower (30%) in the 1955–65 decade than in 1965–79. The same trend earlier observed in east and central parts of Antarctica thus appears to have a very large geographical extent. This well-dated core allows us to undertake a year-to-year comparison between isotopic and climatological data over the 1953–78 period. The mean annual values of the deuterium content are well correlated with the average surface temperature taken over the whole Antarctic Peninsula (δD = (3.4±2.0)T - (98±32)) These data and the experimentally derived δD/δ180 relationship obtained on James Ross Island allow us to deduce a δ180 temperature gradient of 0.44‰°C−1. This low value is discussed in view of a new isotopic model taking into account the partial removal of precipitation and the possible variation of the oceanic source. James Ross Island thus appears suitable as a potential site for reconstructing past climatic changes of the Antarctic Peninsula beyond existing data. Contamination-free techniques were used for sampling and analysing the snow samples. Na, K, Ca, and Al (by atomic absorption), H+ (by titrimetric measurements), SO4 2- and NO3 − (by ion chromatography), and conductivity were determined on more than 100 samples collected in a 4.3 m deep pit. Some of these parameters were also measured on ice-core samples or additional pit samples. Snow impurities are contributed by different aerosol sources: sea salt, continental particles and the small-size particles produced by the conversion of various atmospheric gases. The relative importance of these sources has been estimated. James Ross snow was found always to be slightly acid (1 to 10 μEquiv. l−1 of H+, mainly as sulphuric acid). Nitrate concentrations are much smaller (0.4 μEquiv. l−1 ). Strong seasonal variations are observed for H2SO4 deposition, probably in relation to its formation in the Antarctic atmosphere. Sea-salt deposition exhibits also seasonal variations which can be correlated with storm frequency in the Weddell Sea area. The continental aerosol contribution is weak as indicated by very low Al values. The influence of Deception Island volcanism on the regional aerosol chemistry is examined. A marked increase of snow acidity was detected after the 1967 eruption of this volcano, but no ash layers were observed. The strong variations of the conductivity of melt water are interpreted: it is shown that this parameter is not representative of the extent of sea ice

scholarly journals Detailed ice loss pattern in the northern Antarctic Peninsula: widespread decline driven by ice front retreats

2014 ◽  
Vol 8 (6) ◽  
pp. 2135-2145 ◽  
Author(s):  
T. A. Scambos ◽  
E. Berthier ◽  
T. Haran ◽  
C. A. Shuman ◽  
A. J. Cook ◽  
...  
Keyword(s):  
Mass Loss ◽  
Antarctic Peninsula ◽  
Snow Accumulation ◽  
Stereo Image ◽  
Western Coast ◽  
Elevation Change ◽  
Ice Shelf ◽  
Laser Altimetry ◽  
Ice Volume ◽  
Basin Scale

Abstract. The northern Antarctic Peninsula (nAP, < 66° S) is one of the most rapidly changing glaciated regions on earth, yet the spatial patterns of its ice mass loss at the glacier basin scale have to date been poorly documented. We use satellite laser altimetry and satellite stereo-image topography spanning 2001–2010, but primarily 2003–2008, to map ice elevation change and infer mass changes for 33 glacier basins covering the mainland and most large islands in the nAP. Rates of ice volume and ice mass change are 27.7± 8.6 km3 a−1 and 24.9± 7.8 Gt a−1, equal to −0.73 m a−1 w.e. for the study area. Mass loss is the highest for eastern glaciers affected by major ice shelf collapses in 1995 and 2002, where twelve glaciers account for 60% of the total imbalance. However, losses at smaller rates occur throughout the nAP, at both high and low elevation, despite increased snow accumulation along the western coast and ridge crest. We interpret the widespread mass loss to be driven by decades of ice front retreats on both sides of the nAP, and extended throughout the ice sheet due to the propagation of kinematic waves triggered at the fronts into the interior.

scholarly journals Global change, Antarctic meteorite traps and the East Antarctic ice sheet

1993 ◽  
Vol 39 (132) ◽  
pp. 397-408 ◽  
Author(s):  
G. Delisle
Keyword(s):  
Numerical Models ◽  
Accumulation Rate ◽  
Theoretical Work ◽  
Snow Accumulation ◽  
Ice Thickness ◽  
Ice Caps ◽  
Ice Cap ◽  
Field Evidence ◽  
Victoria Land ◽  
Late Tertiary

AbstractNumerical models to assess the principal response of large ice caps to climatic changes are used as a guide to the interpretation of field evidence of changes in the glaciological regime in the coastal areas of Victoria Land and north Victoria Land, Antarctica. Based on the theoretical work, the following scenario is proposed: areas within about 300 km from the coast of Victoria Land experienced (i) significantly shallower ice slopes and a lesser degree of glaciation during most of the late Tertiary, (ii) steep slopes and thicker ice than today during glacial stages, and (iii) moderate thinning of the ice in intervening interglacial stages.The model predicts, for central regions of Antarctica, a slightly thinner ice cap (lower snow-accumulation rate) during glacial stages, but an estimated 200 m thicker ice cap in warmer Tertiary climates than today. The calculated “Tertiary ice caps” indicate a probable tendency of periodic surges due to basal melting at the outer fringes.Only modest changes of the ice thickness in reasonably good agreement with the model predictions for the current interglacial stage have been observed on four blue-ice fields, all located within 250 km of the coastline. Investigated ice fields include two meteorite traps — the Allan Hills Icefield and the Frontier Mountain meteorite fields. Antarctic meteorite traps are sustained by very specific glaciological conditions — in particular, only moderate changes in ice thickness over time. The sub-ice topography of these fields was determined by radar measurements and reveals a former, very different glaciological regime, which is interpreted as being associated with glacial processes, operative during the late Tertiary.Field evidence for a hypsithermal event during the Holocene is presented.

scholarly journals Global change, Antarctic meteorite traps and the East Antarctic ice sheet

1993 ◽  
Vol 39 (132) ◽  
pp. 397-408 ◽  
Author(s):  
G. Delisle
Keyword(s):  
Numerical Models ◽  
Accumulation Rate ◽  
Theoretical Work ◽  
Snow Accumulation ◽  
Ice Thickness ◽  
Ice Caps ◽  
Ice Cap ◽  
Field Evidence ◽  
Victoria Land ◽  
Late Tertiary

AbstractNumerical models to assess the principal response of large ice caps to climatic changes are used as a guide to the interpretation of field evidence of changes in the glaciological regime in the coastal areas of Victoria Land and north Victoria Land, Antarctica. Based on the theoretical work, the following scenario is proposed: areas within about 300 km from the coast of Victoria Land experienced (i) significantly shallower ice slopes and a lesser degree of glaciation during most of the late Tertiary, (ii) steep slopes and thicker ice than today during glacial stages, and (iii) moderate thinning of the ice in intervening interglacial stages.The model predicts, for central regions of Antarctica, a slightly thinner ice cap (lower snow-accumulation rate) during glacial stages, but an estimated 200 m thicker ice cap in warmer Tertiary climates than today. The calculated “Tertiary ice caps” indicate a probable tendency of periodic surges due to basal melting at the outer fringes.Only modest changes of the ice thickness in reasonably good agreement with the model predictions for the current interglacial stage have been observed on four blue-ice fields, all located within 250 km of the coastline. Investigated ice fields include two meteorite traps — the Allan Hills Icefield and the Frontier Mountain meteorite fields. Antarctic meteorite traps are sustained by very specific glaciological conditions — in particular, only moderate changes in ice thickness over time. The sub-ice topography of these fields was determined by radar measurements and reveals a former, very different glaciological regime, which is interpreted as being associated with glacial processes, operative during the late Tertiary.Field evidence for a hypsithermal event during the Holocene is presented.

scholarly journals Air Temperature and Snow Accumulation in the Antarctic Peninsula During the Past 50 Years (Abstract)

1988 ◽  
Vol 11 ◽  
pp. 207-207 ◽  
Author(s):  
David A. Peel ◽  
Robert Mulvaney
Keyword(s):  
Antarctic Peninsula ◽  
Accumulation Rate ◽  
Ice Sheet ◽  
Ice Cores ◽  
Snow Accumulation ◽  
The West ◽  
Climate Type ◽  
The Past ◽  
The Antarctic ◽  
Noise Factors

Trends in climate affecting the West Antarctic ice sheet may be detected first in the Antarctic Peninsula region. Although the area contains the most comprehensive weather records for any part of Antarctica, reliable snow-accumulation data are lacking.Mainly as a result of the large snow-accumulation rate in the region (typically in the range 4.0–10.0 kg m−2 a−1), stratigraphie evidence of climate derived from ice cores can be resolved in much greater detail than is possible over most of the continent. Ice cores have been drilled at two sites, representing the extremes of climate type encountered in the region. A 133 m core has been obtained from Dolleman Island (70°35.2′S, 60°55.5′W) to represent the continental-type climate of the Weddell coast region, and an 87 m core has been obtained from the Palmer Land plateau (74°01′S, 70°38′W) to represent the more maritime regime of the west coast and central areas. Replicated cores were obtained at both sites in order to assess the contribution of local noise factors to the climatic signal preserved in the cores. Climatic trends during the period 1938–86 have been assessed on the basis of stable-isotope analysis of the top 47 m of the Palmer Land core and of the top 32 m of the Dolleman Island core.A statistical analysis of derived profiles of mean annual δ18O and accumulation rate indicates that the local noise factors at these sites are sufficiently small that data averaged over periods as short as 5 years should reveal climatic shifts at the level of 0.2% and 5% respectively. These changes are much smaller than trends that have actually occurred during the past 50 years.The most notable trend over the past 30 years is an increase of more than 30% in the snow-accumulation rate that has occurred in parallel with an overall temperature increase of 0.06°C/a during the same period. Increases of similar magnitude can be inferred from studies in East Antarctica, and may be related to a significant increase in precipitation rate that has been documented recently at mid-to high-latitude stations in the Northern Hemisphere. The finding may have relevance to studies of the possible consequences of a CO2-induced climate change. More extensive accumulation time series are now required from Antarctica, if satisfactory models of the long-term balance of the ice sheet are to be derived.

scholarly journals Variable glacier response to atmospheric warming, northern Antarctic Peninsula, 1988–2009

2012 ◽  
Vol 6 (5) ◽  
pp. 1031-1048 ◽  
Author(s):  
B. J. Davies ◽  
J. L. Carrivick ◽  
N. F. Glasser ◽  
M. J. Hambrey ◽  
J. L. Smellie
Keyword(s):  
Antarctic Peninsula ◽  
Dynamic Equilibrium ◽  
Eastern Coast ◽  
Slope Aspect ◽  
Western Coast ◽  
Ice Shelf ◽  
Tidewater Glaciers ◽  
Temperature And Precipitation ◽  
Glacier Recession ◽  
James Ross Island

Abstract. The northern Antarctic Peninsula has recently exhibited ice-shelf disintegration, glacier recession and acceleration. However, the dynamic response of land-terminating, ice-shelf tributary and tidewater glaciers has not yet been quantified or assessed for variability, and there are sparse data for glacier classification, morphology, area, length or altitude. This paper firstly classifies the area, length, altitude, slope, aspect, geomorphology, type and hypsometry of 194 glaciers on Trinity Peninsula, Vega Island and James Ross Island in 2009 AD. Secondly, this paper documents glacier change 1988–2009. In 2009, the glacierised area was 8140±262 km2. From 1988–2001, 90% of glaciers receded, and from 2001–2009, 79% receded. This equates to an area change of −4.4% for Trinity Peninsula eastern coast glaciers, −0.6% for western coast glaciers, and −35.0% for ice-shelf tributary glaciers from 1988–2001. Tidewater glaciers on the drier, cooler eastern Trinity Peninsula experienced fastest shrinkage from 1988–2001, with limited frontal change after 2001. Glaciers on the western Trinity Peninsula shrank less than those on the east. Land-terminating glaciers on James Ross Island shrank fastest in the period 1988–2001. This east-west difference is largely a result of orographic temperature and precipitation gradients across the Antarctic Peninsula, with warming temperatures affecting the precipitation-starved glaciers on the eastern coast more than on the western coast. Reduced shrinkage on the western Peninsula may be a result of higher snowfall, perhaps in conjunction with the fact that these glaciers are mostly grounded. Rates of area loss on the eastern side of Trinity Peninsula are slowing, which we attribute to the floating ice tongues receding into the fjords and reaching a new dynamic equilibrium. The rapid shrinkage of tidewater glaciers on James Ross Island is likely to continue because of their low elevations and flat profiles. In contrast, the higher and steeper tidewater glaciers on the eastern Antarctic Peninsula will attain more stable frontal positions after low-lying ablation areas are removed, reaching equilibrium more quickly.

scholarly journals Air Temperature and Snow Accumulation in the Antarctic Peninsula During the Past 50 Years (Abstract)

1988 ◽  
Vol 11 ◽  
pp. 207 ◽  
Author(s):  
David A. Peel ◽  
Robert Mulvaney
Keyword(s):  
Antarctic Peninsula ◽  
Accumulation Rate ◽  
Ice Sheet ◽  
Ice Cores ◽  
Snow Accumulation ◽  
The West ◽  
Climate Type ◽  
The Past ◽  
The Antarctic ◽  
Noise Factors

Trends in climate affecting the West Antarctic ice sheet may be detected first in the Antarctic Peninsula region. Although the area contains the most comprehensive weather records for any part of Antarctica, reliable snow-accumulation data are lacking. Mainly as a result of the large snow-accumulation rate in the region (typically in the range 4.0–10.0 kg m−2 a−1), stratigraphie evidence of climate derived from ice cores can be resolved in much greater detail than is possible over most of the continent. Ice cores have been drilled at two sites, representing the extremes of climate type encountered in the region. A 133 m core has been obtained from Dolleman Island (70°35.2′S, 60°55.5′W) to represent the continental-type climate of the Weddell coast region, and an 87 m core has been obtained from the Palmer Land plateau (74°01′S, 70°38′W) to represent the more maritime regime of the west coast and central areas. Replicated cores were obtained at both sites in order to assess the contribution of local noise factors to the climatic signal preserved in the cores. Climatic trends during the period 1938–86 have been assessed on the basis of stable-isotope analysis of the top 47 m of the Palmer Land core and of the top 32 m of the Dolleman Island core. A statistical analysis of derived profiles of mean annual δ18O and accumulation rate indicates that the local noise factors at these sites are sufficiently small that data averaged over periods as short as 5 years should reveal climatic shifts at the level of 0.2% and 5% respectively. These changes are much smaller than trends that have actually occurred during the past 50 years. The most notable trend over the past 30 years is an increase of more than 30% in the snow-accumulation rate that has occurred in parallel with an overall temperature increase of 0.06°C/a during the same period. Increases of similar magnitude can be inferred from studies in East Antarctica, and may be related to a significant increase in precipitation rate that has been documented recently at mid-to high-latitude stations in the Northern Hemisphere. The finding may have relevance to studies of the possible consequences of a CO2-induced climate change. More extensive accumulation time series are now required from Antarctica, if satisfactory models of the long-term balance of the ice sheet are to be derived.

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