scholarly journals Future Antarctic snow accumulation trend is dominated by atmospheric synoptic-scale events

2020 ◽  
Vol 1 (1) ◽  
Author(s):  
Quentin Dalaiden ◽  
Hugues Goosse ◽  
Jan T. M. Lenaerts ◽  
Marie G. P. Cavitte ◽  
Naomi Henderson
Keyword(s):  
Large Scale ◽  
Ice Sheet ◽  
Snow Accumulation ◽  
Synoptic Scale ◽  
Antarctic Ice Sheet ◽  
Decadal Scale ◽  
Antarctic Snow ◽  
Atmospheric Moisture Budget ◽  
The Antarctic ◽  
Accumulation Trend

AbstractOver the last century, the increase in snow accumulation has partly mitigated the total dynamic Antarctic Ice Sheet mass loss. However, the mechanisms behind this increase are poorly understood. Here we analyze the Antarctic Ice Sheet atmospheric moisture budget based on climate reanalysis and model simulations to reveal that the interannual variability of regional snow accumulation is controlled by both the large-scale atmospheric circulation and short-lived synoptic-scale events (i.e. storm systems). Yet, when considering the entire continent at the multi-decadal scale, only the synoptic-scale events can explain the recent and expected future snow accumulation increase. In a warmer climate induced by climate change, these synoptic-scale events transport air that can contain more humidity due to the increasing temperatures leading to more precipitation on the continent. Our findings highlight that the multi-decadal and interannual snow accumulation variability is governed by different processes, and that we thus cannot rely directly on the mechanisms driving interannual variations to predict long-term changes in snow accumulation in the future.

scholarly journals Snow surface height variations on the Antarctic ice sheet in Princess Elizabeth Land, Antarctica: 1 year of data from an automatic weather station

2004 ◽  
Vol 39 ◽  
pp. 181-187 ◽  
Author(s):  
Qin Dahe ◽  
Xiao Cunde ◽  
Ian Allison ◽  
Bian Lingen ◽  
Rod Stephenson ◽  
...  
Keyword(s):  
Ice Sheet ◽  
Cloud Amount ◽  
Snow Accumulation ◽  
Strong Wind ◽  
Weather Station ◽  
Automatic Weather Station ◽  
Antarctic Ice Sheet ◽  
Total Cloud Amount ◽  
Surface Snow ◽  
The Antarctic

AbstractThe net surface snow accumulation on the Antarctic ice sheet is determined by a combination of precipitation, sublimation and wind redistribution. We present a 1 year record of hourly snow-height measurements that shows its seasonal variability. The measurements were made with an ultrasonic sensor mounted on an automatic weather station (AWS) installed at LGB69, Princess Elizabeth Land, Antarctica (70.835˚S, 77.075˚E; 1850 ma.s.l.). The average accumulation at this site is approximately 0.70 m snow a–1. Throughout the winter, between April and September, there was little change in surface snow height. The strongest accumulation occurred during the period October–March, with four episodic increases occurring during 2002. These episodic events coincided with obvious humidity ‘pulses’ and decreases of incoming solar radiation as recorded by the AWS. Observations of the total cloud amount at Davis station, 160 km north-northeast of LGB69, showed good correlation with major accumulation events recorded at LGB69. There was an obvious anticorrelation between the lowest cloud height at Davis and the daily accumulation rate at LGB69. Although there was no correlation over the total year between wind speed and accumulation at LGB69, large individual accumulation events are associated with episodes of strong wind. Strong accumulation events at LGB69 are associated with major storms in the region and inland transport of moist air masses from the coast.

scholarly journals The glacial geomorphology of the Antarctic ice sheet bed

2014 ◽  
Vol 26 (6) ◽  
pp. 724-741 ◽  
Author(s):  
Stewart S.R. Jamieson ◽  
Chris R. Stokes ◽  
Neil Ross ◽  
David M. Rippin ◽  
Robert G. Bingham ◽  
...  
Keyword(s):  
Large Scale ◽  
Landscape Evolution ◽  
Ice Sheets ◽  
Ice Sheet ◽  
Glacial Erosion ◽  
Antarctic Ice Sheet ◽  
The Past ◽  
Valley Network ◽  
The Antarctic ◽  
Antarctic Ice Sheets

AbstractIn 1976, David Sugden and Brian John developed a classification for Antarctic landscapes of glacial erosion based upon exposed and eroded coastal topography, providing insight into the past glacial dynamics of the Antarctic ice sheets. We extend this classification to cover the continental interior of Antarctica by analysing the hypsometry of the subglacial landscape using a recently released dataset of bed topography (BEDMAP2). We used the existing classification as a basis for first developing a low-resolution description of landscape evolution under the ice sheet before building a more detailed classification of patterns of glacial erosion. Our key finding is that a more widespread distribution of ancient, preserved alpine landscapes may survive beneath the Antarctic ice sheets than has been previously recognized. Furthermore, the findings suggest that landscapes of selective erosion exist further inland than might be expected, and may reflect the presence of thinner, less extensive ice in the past. Much of the selective nature of erosion may be controlled by pre-glacial topography, and especially by the large-scale tectonic structure and fluvial valley network. The hypotheses of landscape evolution presented here can be tested by future surveys of the Antarctic ice sheet bed.

Climate parameters influencing satellite-based volume and elevation changes of the Antarctic ice sheet

2020 ◽  
Author(s):  
Athul Kaitheri ◽  
Anthony Mémin ◽  
Frédérique Rémy
Keyword(s):  
Mass Balance ◽  
Ice Sheet ◽  
Snow Accumulation ◽  
Amundsen Sea ◽  
Antarctic Ice Sheet ◽  
Changing Climate ◽  
Basin Scale ◽  
Elevation Changes ◽  
The Antarctic ◽  
Grace Mission

<p>Precisely quantifying the Antarctic Ice Sheet (AIS) mass balance remains a challenge as several processes compete at differing degrees in the basin-scale with regional variations. Understanding of changes in AIS has been largely based on observations from various altimetry missions and Gravity Recovery And Climate Experiment (GRACE) missions due to its scale and coverage. Analysis of linear trends in surface height variations of AIS since the early 1990s showed multiple variabilities in the rate of changes over the period of time. These observations are a reflection of various underlying ice sheet processes. Therefore understanding the processes that interact on the ice sheet is important to precisely determine the response of the ice sheet to a rapidly changing climate.</p><p>Changing climate constitutes variations in major short term processes including snow accumulation and surface melting. Variations in accumulation rate and temperature at the ice sheet surface cause changes in the firn compaction (FC) rate. Variations in the FC rate change the AIS thickness, that should be detected from altimetry, but do not change its mass, as observed by the GRACE mission. We focus our study on the seasonal and interannual changes in the elevation and mass of the AIS. We use surface elevation changes from Envisat data and gravity changes derived from the latest GRACE solutions between 10/2002 and 10/2010. As mass changes observed using the GRACE mission is strongly impacted by long term isostasy, as it involves mantle mass redistribution, we remove from all dataset an 8-year trend. We use weather variable historical data solutions including surface mass balance, temperature and wind velocities from the regional climate model RACMO2.3p2 as input to an FC model to estimate AIS elevation changes. We obtain a very good correlation between height change estimates from GRACE, Envisat and RACMO2.3p2 at several places such as along the coast of Dronning Maud Land, Wilkes land and Amundsen sea sector. Considerable differences in Oates and Mac Robertson regions, with a strong seasonal signal in Envisat estimates, reflect spatial variability in physical parameters of the surface of the AIS due to climate parameter changes such as winds.</p>

scholarly journals Large-Scale Numerical Modelling of the Antarctic Ice Sheet

1982 ◽  
Vol 3 ◽  
pp. 42-49 ◽  
Author(s):  
W.F. Budd ◽  
I.N. Smith
Keyword(s):  
Sea Level ◽  
Large Scale ◽  
Accumulation Rate ◽  
Ice Sheet ◽  
Ice Thickness ◽  
Ice Flow ◽  
Antarctic Ice Sheet ◽  
Flow Parameters ◽  
The Antarctic ◽  
Thinning Rate

A large-scale dynamic numerical model of the Antarctic ice sheet has been developed to study its present state of ice flow and mass balance as well as its response to long-term changes of climate or sea-level.The flow of ice over a two-dimensional grid is determined from the ice thickness, the basal shear stress, the bedrock depth, and ice flow parameters derived from velocities of existing ice sheets. The change in ice thickness with time is governed by the continuity equation involving the ice flux divergence and the ice accumulation or ablation. At the ice sheet seaward boundary, a floating criterion and floating ice thinning rate apply. Bedrock depression with a time-delayed response dependent on the history of the ice load is also included.A 61 × 61 point grid with 100 km spacing has been used to represent the ice-sheet surface, bedrock, and accumulation rate. The model has been used to simul a te the growth of the present ice sheet and i ts reaction to changes of sea-level, bedrock depression, accumulation rate, ice flow parameters, and the iceshelf thinning rate.Preliminary results suggest that the present ice sheet is not in equilibrium but rather is still adjusting to changes of these parameters.

scholarly journals Altimetric observations of surface characteristics of the Antarctic ice sheet

1997 ◽  
Vol 43 (144) ◽  
pp. 265-275 ◽  
Author(s):  
Benoît Legrésy ◽  
Frédérique Rémy
Keyword(s):  
Large Scale ◽  
Ice Sheet ◽  
Leading Edge ◽  
Small Scale ◽  
Height Measurement ◽  
Trailing Edge ◽  
Antarctic Ice Sheet ◽  
Linear Effect ◽  
Continental Scale ◽  
The Antarctic

AbstractThe aim of this paper is to investigate the geophysical characteristics of the Antarctic ice sheet using radar altimetric observations. To do this, we use an altimetric waveform simulator, in situ observations, ERS-1 (European remote-sensing satellite) data and SPOT (Satellite pour l’observation de la terre) images. The small-scale study takes place at Dome C, Terre Adélie, which is a relatively flat region with gentle undulations and low wind speed. Despite this, the altimetric waveform parameters (height, energy, leading edge and trailing edge) are highly noisy. The effect of undulations on the waveform parameters is found to be dominant. The combination of a subsurface signal and a rough surface produces a linear effect on the altimetric backscattering or on the trailing edge of the waveform, but a strongly non-linear effect on the leading edge of the waveform or height estimation. As a consequence, the height measurement is very sensitive to the altimeter technical or orbital characteristics and is not reproducible from one mission to another. Observations show sastrugi fields that enhance the leading edge and affect the whole waveform. Observed local backscattering changes, probably due to local variations in surface microroughness, enhance the backscattered energy and may artificially create a topographic signal. The continental-scale study shows coherent patterns. Even if both surface and subsurface components affect the altimetric observation, the large-scale signal is mostly controlled by surface backscattering variations. The surface or near-subsurface characteristics of the snowpack may then be reached by altimetric observations.

scholarly journals Altimetric observations of surface characteristics of the Antarctic ice sheet

1997 ◽  
Vol 43 (144) ◽  
pp. 265-275 ◽  
Author(s):  
Benoît Legrésy ◽  
Frédérique Rémy
Keyword(s):  
Large Scale ◽  
Ice Sheet ◽  
Leading Edge ◽  
Small Scale ◽  
Height Measurement ◽  
Trailing Edge ◽  
Antarctic Ice Sheet ◽  
Linear Effect ◽  
Continental Scale ◽  
The Antarctic

AbstractThe aim of this paper is to investigate the geophysical characteristics of the Antarctic ice sheet using radar altimetric observations. To do this, we use an altimetric waveform simulator, in situ observations, ERS-1 (European remote-sensing satellite) data and SPOT (Satellite pour l’observation de la terre) images. The small-scale study takes place at Dome C, Terre Adélie, which is a relatively flat region with gentle undulations and low wind speed. Despite this, the altimetric waveform parameters (height, energy, leading edge and trailing edge) are highly noisy. The effect of undulations on the waveform parameters is found to be dominant. The combination of a subsurface signal and a rough surface produces a linear effect on the altimetric backscattering or on the trailing edge of the waveform, but a strongly non-linear effect on the leading edge of the waveform or height estimation. As a consequence, the height measurement is very sensitive to the altimeter technical or orbital characteristics and is not reproducible from one mission to another. Observations show sastrugi fields that enhance the leading edge and affect the whole waveform. Observed local backscattering changes, probably due to local variations in surface microroughness, enhance the backscattered energy and may artificially create a topographic signal. The continental-scale study shows coherent patterns. Even if both surface and subsurface components affect the altimetric observation, the large-scale signal is mostly controlled by surface backscattering variations. The surface or near-subsurface characteristics of the snowpack may then be reached by altimetric observations.

scholarly journals Origin and dynamic significance of longitudinal structures ("flow stripes") in the Antarctic Ice Sheet

2015 ◽  
Vol 3 (2) ◽  
pp. 239-249 ◽  
Author(s):  
N. F. Glasser ◽  
S. J. A. Jennings ◽  
M. J. Hambrey ◽  
B. Hubbard
Keyword(s):  
Large Scale ◽  
Ice Sheet ◽  
Surface Structures ◽  
Dimensional Structure ◽  
Ice Flow ◽  
Antarctic Ice Sheet ◽  
Flow Perturbation ◽  
Ice Surface ◽  
Ice Stream ◽  
The Antarctic

Abstract. Longitudinal ice-surface structures in the Antarctic Ice Sheet can be traced continuously down-ice for distances of up to 1200 km. A map of the distribution of ~ 3600 of these features, compiled from satellite images, shows that they mirror the location of fast-flowing glaciers and ice streams that are dominated by basal sliding rates above tens of metres per annum and are strongly guided by subglacial topography. Longitudinal ice-surface structures dominate regions of converging flow, where ice flow is subject to non-coaxial strain and simple shear. They can be traced continuously through crevasse fields and through blue-ice areas, indicating that they represent the surface manifestation of a three-dimensional structure, interpreted as foliation. Flow lines are linear and undeformed for all major flow units described here in the Antarctic Ice Sheet except for the Kamb Ice Stream and the Institute and Möller Ice Stream areas, where areas of flow perturbation are evident. Parcels of ice along individual flow paths on the Lambert Glacier, Recovery Glacier, Byrd Glacier and Pine Island Glacier may reside in the glacier system for ~ 2500 to 18 500 years. Although it is unclear how long it takes for these features to form and decay, we infer that the major ice-flow configuration of the ice sheet may have remained largely unchanged for the last few hundred years, and possibly even longer. This conclusion has implications for our understanding of the long-term landscape evolution of Antarctica, including large-scale patterns of glacial erosion and deposition.

scholarly journals Variability of black carbon deposition to the East Antarctic Plateau, AD 1800–2000

2011 ◽  
Vol 11 (11) ◽  
pp. 31091-31114 ◽  
Author(s):  
M. M. Bisiaux ◽  
R. Edwards ◽  
J. R. McConnell ◽  
M. R. Albert ◽  
H. Anschütz ◽  
...  
Keyword(s):  
Black Carbon ◽  
Geometric Mean ◽  
Ice Core ◽  
Ice Sheet ◽  
Ice Cores ◽  
Snow Accumulation ◽  
Antarctic Ice Sheet ◽  
Decadal Scale ◽  
History Of ◽  
Aerosol Emissions

Abstract. Refractory black carbon aerosols (rBC) from biomass burning and fossil fuel combustion are deposited to the Antarctic ice sheet and preserve a history of emissions and long-range transport from low latitudes. Antarctic ice core rBC records may thus provide information with respect to past combustion aerosol emissions and atmospheric circulation. Here, we present six East Antarctic ice core records of rBC concentrations and fluxes covering the last two centuries with approximately annual resolution (cal. yr. 1800 to 2000). The ice cores were drilled in disparate regions of the high East Antarctic ice sheet, at different elevations and net snow accumulation rates. Annual rBC concentrations were log-normally distributed and geometric means of annual concentrations ranged from 0.10 to 0.18 μg kg−1. Average rBC fluxes were determined over the time periods 1800 to 2000 and 1963 to 2000 and ranged from 3.4 to 15.5 μg kg−1 m−2 a−1 and 3.6 to 21.8 μg kg−1 m−2 a−1 respectively. Geometric-mean concentrations spanning 1800 to 2000 increased linearly with elevation at a rate of 0.025 μg kg−1/500 m. Spectral analysis of the records revealed significant decadal scale variability, which at several sites was comparable to decadal ENSO variability.

scholarly journals Mass gains of the Antarctic ice sheet exceed losses

2015 ◽  
Vol 61 (230) ◽  
pp. 1019-1036 ◽  
Author(s):  
H. Jay Zwally ◽  
Jun Li ◽  
John W. Robbins ◽  
Jack L. Saba ◽  
Donghui Yi ◽  
...  
Keyword(s):  
Sea Level Rise ◽  
Sea Level ◽  
Ice Sheet ◽  
Snow Accumulation ◽  
Antarctic Ice Sheet ◽  
Drainage Systems ◽  
Ice Cloud ◽  
West Antarctic ◽  
Global Sea Level ◽  
The Antarctic

AbstractMass changes of the Antarctic ice sheet impact sea-level rise as climate changes, but recent rates have been uncertain. Ice, Cloud and land Elevation Satellite (ICESat) data (2003–08) show mass gains from snow accumulation exceeded discharge losses by 82 ± 25 Gt a−1, reducing global sea-level rise by 0.23 mm a−1. European Remote-sensing Satellite (ERS) data (1992–2001) give a similar gain of 112 61 Gt a−1. Gains of 136 Gt a−1 in East Antarctica (EA) and 72 Gt a−1 in four drainage systems (WA2) in West Antarctic (WA) exceed losses of 97 Gt a−1 from three coastal drainage systems (WA1) and 29 Gt a−1 from the Antarctic Peninsula (AP). EA dynamic thickening of 147 Gt a−1 is a continuing response to increased accumulation (>50%) since the early Holocene. Recent accumulation loss of 11 Gt a−1 in EA indicates thickening is not from contemporaneous snowfall increases. Similarly, the WA2 gain is mainly (60 Gt a−1) dynamic thickening. In WA1 and the AP, increased losses of 66 ± 16 Gt a−1 from increased dynamic thinning from accelerating glaciers are 50% offset by greater WA snowfall. The decadal increase in dynamic thinning in WA1 and the AP is approximately one-third of the long-term dynamic thickening in EA and WA2, which should buffer additional dynamic thinning for decades.

The climatic effects of large-scale surges of ice sheets

1969 ◽  
Vol 6 (4) ◽  
pp. 911-918 ◽  
Author(s):  
A. T. Wilson
Keyword(s):  
Sea Level ◽  
Large Scale ◽  
Ice Sheets ◽  
Ice Sheet ◽  
Considerable Effect ◽  
Ice Age ◽  
Ice Shelf ◽  
Climatic Effects ◽  
Antarctic Ice Sheet ◽  
The Antarctic

Surges in ice masses of glacier size are now well accepted in glaciology. There seems no reason why a similar phenomenon should not occur in bodies of ice as large as continental ice sheets.If a continental ice sheet surged into the sea it would have a considerable effect on world sea-level. This is proposed as the mechanism of past sea-level fluctuations (cyclothems) of the Carboniferous and Tertiary.The effect of a surge of the Antarctic Ice Sheet on world climate is considered, with particular reference to the origin of ice ages.The requirements of an ice-age mechanism are discussed and it is concluded that a periodic surge of the Antarctic Ice Sheet, perhaps induced by a decrease in insolation to the south polar region, has all the requirements of an ice-age inducing mechanism. In particular, any oscillating system must have capacitance (storage) and impedance (resistance). It is not easy to find a system in nature with a sufficiently long period of oscillation. However, the build up of ice on Antarctica would provide a sufficiently slow charging of storage, and the ice sheet itself would provide the storage to yield a system of long enough period.It is proposed that when the Antarctic Ice Sheet surges, a large ice shelf is produced which increases the albedo of the Earth. The resulting cooling leads to the formation of secondary ice sheets in the Northern Hemisphere, which in turn leads to a further increase in albedo and further cooling. The break up of the ice shelf and its replacement by ocean would lead to a large decrease in the Earth's albedo. The resulting warming would lead to the rapid melting of the subsiduary ice sheets and the ending of the ice age.

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