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Title |
Paleoclimates: what do we learn from deep ice cores?
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Type |
Journal Article |
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Year |
2010 |
Publication |
Wiley Interdisciplinary Reviews: Climate Change |
Abbreviated Journal |
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Volume |
1 |
Issue |
5 |
Pages |
654 -669 |
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Programme |
458 |
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Publisher  |
John Wiley & Sons, Inc. |
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ISSN |
1757-7799 |
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Approved |
yes |
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Call Number |
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Serial |
209 |
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Author |
Van Petegem, F.,; Collins, T.,; Meuwis, M.-A.,; Gerday, C.,; Feller, G.,; Van Beeumen, J., |
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Title |
Crystallization and preliminary X-ray analysis of a xylanase from the psychrophile Pseudoalteromonas haloplanktis |
Type |
Journal Article |
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Year |
2002 |
Publication |
Acta crystallographica section d-biological crystallography |
Abbreviated Journal |
Acta Crystallogr. D Biol. Crystallogr. |
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Volume |
58 |
Issue |
9 |
Pages |
1494-1496 |
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Keywords |
psychrophiles; cold-adapted enzyme; glycosyl hydrolases |
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Abstract |
The 46 kDa xylanase from the Antarctic microorganism Pseudoalteromonas haloplanktis is an enzyme that efficiently catalyzes reactions at low temperatures. Here, the crystallization of both the native protein and the SeMet-substituted enzyme and data collection from both crystals using synchrotron radiation are described. The native data showed that the crystals diffract to 1.3 A resolution and belong to space group P212121, with unit-cell parameters a = 50.87, b = 90.51, c = 97.23 A. SAD data collected at the peak of the selenium absorption edge proved to be sufficient to determine the heavy-atom configuration and to obtain electron density of good quality. |
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193 |
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Publisher |
International Union of Crystallography |
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ISSN |
0907-4449 |
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Notes |
doi:10.1107/S0907444902011666 |
Approved |
yes |
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Call Number |
IPEV @ Thierry.Lemaire @ |
Serial |
5579 |
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Author |
Delmont Tom O, Malandain Cedric, Prestat Emmanuel, Larose Catherine, Monier Jean-Michel, Simonet Pascal, Vogel Timothy M, |
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Title |
Metagenomic mining for microbiologists
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Type |
Journal Article |
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Year |
2011 |
Publication |
ISME JOURNAL |
Abbreviated Journal |
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Volume |
5 |
Issue |
12 |
Pages |
1837-1843 |
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Keywords |
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Abstract |
Microbial ecologists can now start digging into the accumulating mountains of metagenomic data to uncover the occurrence of functional genes and their correlations to microbial community members. Limitations and biases in DNA extraction and sequencing technologies impact sequence distributions, and therefore, have to be considered. However, when comparing metagenomes from widely differing environments, these fluctuations have a relatively minor role in microbial community discrimination. As a consequence, any functional gene or species distribution pattern can be compared among metagenomes originating from various environments and projects. In particular, global comparisons would help to define ecosystem specificities, such as involvement and response to climate change (for example, carbon and nitrogen cycle), human health risks (eg, presence of pathogen species, toxin genes and viruses) and biodegradation capacities. Although not all scientists have easy access to high-throughput sequencing technologies, they do have access to the sequences that have been deposited in databases, and therefore, can begin to intensively mine these metagenomic data to generate hypotheses that can be validated experimentally. Information about metabolic functions and microbial species compositions can already be compared among metagenomes from different ecosystems. These comparisons add to our understanding about microbial adaptation and the role of specific microbes in different ecosystems. Concurrent with the rapid growth of sequencing technologies, we have entered a new age of microbial ecology, which will enable researchers to experimentally confirm putative relationships between microbial functions and community structures. |
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Programme |
399 |
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Thesis |
Bachelor's thesis |
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Publisher |
International Society for Microbial Ecology |
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Original Title |
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Series Volume |
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Edition |
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ISSN |
1751-7362 |
ISBN |
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Notes |
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Approved |
yes |
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Call Number |
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Serial |
3335 |
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Author |
GENTHON C, MAGAND O, KRINNER G, FILY M, |
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Title |
Do climate models underestimate snow accumulation on the Antarctic plateau? A re-evaluation of/from in situ observations in East Wilkes and Victoria Lands
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Type |
Journal Article |
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Year |
2009 |
Publication |
Annals of glaciology |
Abbreviated Journal |
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Volume |
50 |
Issue |
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Pages |
61 -65 |
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Abstract |
It has been suggested that meteorological and climate models underestimate snow accumulation on the Antarctic plateau, because accumulation (or surface mass balance (SMB)) is dominated by clear-sky precipitation while this process is not properly taken into account in the models. Here, we show that differences between model and field SMB data are much reduced when the in situ SMB reports used to evaluate the models are filtered through quality-control criteria and less reliable reports are subsequently left out. We thus argue that, although not necessarily unsupported, model biases and their interpretations in terms of clear-sky vs synoptic precipitation on the Antarctic plateau may have been overstated in the past. To avoid such misleading issues, it is important that in situ SMB reports of insufficient or unassessed reliability are discarded, even at the cost of a strong reduction in spatial sampling and coverage.
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Programme |
1013 |
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Thesis |
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Publisher |
International Glaciological Society |
Place of Publication |
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Original Title |
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Series Editor |
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Series Title |
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Abbreviated Series Title |
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Series Volume |
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Series Issue |
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Edition |
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ISSN |
0260-3055 |
ISBN |
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Medium |
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Area |
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Expedition |
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Conference |
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Notes |
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Approved |
yes |
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Call Number |
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Serial |
1912 |
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Author |
Genthon C, Krinner G, Castebrunet H, |
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Title |
Antarctic precipitation and climate-change predictions: horizontal resolution and margin vs plateau issues
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Type |
Journal Article |
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Year |
2009 |
Publication |
Annals of Glaciology |
Abbreviated Journal |
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Volume |
50 |
Issue |
50 |
Pages |
55 -60 |
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Keywords |
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Abstract |
All climate models participating in the Fourth Assessment Report of the Intergovernmental Panel on Climate Change, as made available by the Program for Climate Model Diagnosis and Intercomparison (PCMDI) as the Coupled Model Intercomparison Project 3 (CMIP3) archive, predict a significant surface warming of Antarctica by the end of the 21st century under a moderate (SRESA1B) greenhouse-gas scenario. All models but one predict a concurrent precipitation increase but with a large scatter of results. The models with finer horizontal resolution tend to predict a larger precipitation increase. Because modeled Antarctic surface mass balance is known to be sensitive to horizontal resolution, extrapolating predictions from the different models with respect to model resolution may provide simple yet better multi-model estimates of Antarctic precipitation change than mere averaging or even more complex approaches. Using such extrapolation, a conservative estimate of the predicted precipitation increase at the end of the 21st century is +30 kg m2a1 on the grounded ice sheet, corresponding to a >1 mm a1 sea-level rise. About three-quarters of this rise originates from the marginal regions of the Antarctic ice sheet with surface elevation below 2250 m. This is where field programs are most urgently needed to better understand and monitor accumulation at the surface of Antarctica, and to improve and verify prediction models.
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Programme |
1013 |
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Corporate Author |
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Thesis |
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Publisher |
International Glaciological Society |
Place of Publication |
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Summary Language |
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Series Editor |
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Series Title |
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Abbreviated Series Title |
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Series Volume |
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Series Issue |
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Edition |
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ISSN |
0260-3055 |
ISBN |
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Medium |
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Area |
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Expedition |
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Conference |
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Notes |
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Approved |
yes |
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Call Number |
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Serial |
1927 |
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Author |
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Title |
Modeling time series of microwave brightness temperature at Dome C, Antarctica, using vertically resolved snow temperature and microstructure measurements
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Type |
Journal Article |
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Year |
2011 |
Publication |
Journal of Glaciology |
Abbreviated Journal |
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Volume |
57 |
Issue |
201 |
Pages |
171 -182 |
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Keywords |
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Abstract |
Time series of observed microwave brightness temperatures at Dome C, East Antarctic plateau, were modeled over 27 months with a multilayer microwave emission model based on dense-medium radiative transfer theory. The modeled time series of brightness temperature at 18.7 and 36.5 GHz were compared with Advanced Microwave Scanning Radiometer-EOS observations. The model uses in situ high-resolution vertical profiles of temperature, snow density and grain size. The snow grain-size profile was derived from near-infrared (NIR) reflectance photography of a snow pit wall in the range 850-1100 nm. To establish the snow grain-size profile, from the NIR reflectance and the specific surface area of snow, two empirical relationships and a theoretical relationship were considered. In all cases, the modeled brightness temperatures were overestimated, and the grain-size profile had to be scaled to increase the scattering by snow grains. Using a scaling factor and a constant snow grain size below 3 m depth (i.e. below the image-derived snow pit grain-size profile), brightness temperatures were explained with a root-mean-square error close to 1 K. Most of this error is due to an overestimation of the predicted brightness temperature in summer at 36.5 GHz.
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Programme |
454 |
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Corporate Author |
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Thesis |
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Publisher |
International Glaciological Society |
Place of Publication |
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Series Editor |
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Series Title |
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Edition |
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ISBN |
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Expedition |
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Conference |
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Notes |
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Approved |
yes |
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Call Number |
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Serial |
2045 |
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Author |
Brucker Ludovic, Picard Ghislain, Fily Michel, |
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Title |
Snow grain-size profiles deduced from microwave snow emissivities in Antarctica
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Type |
Journal Article |
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Year |
2010 |
Publication |
Journal Of Glaciology |
Abbreviated Journal |
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Volume |
56 |
Issue |
197 |
Pages |
514 -526 |
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Keywords |
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Abstract |
Spaceborne microwave radiometers are an attractive tool for observing Antarctic climate because their measurements are related to the snow temperature. However, the conversion from microwave emission to snow temperature is not simple and strongly depends on the emissivity through S snow properties. This difficulty in predicting the snow property profile for Antarctic conditions is the main bottleneck in the retrieval of accurate climate information from microwave radiometers. We attempt to explain the vertically polarized emissivity at 19.3 and 37 GHz derived from brightness temperatures acquired by the Special Sensor Microwave/Imager (SSM/I) and physical temperature from the ERA-40 re-analysis. In Antarctica the snow emissivities at 19.3 and 37 GHz are nearly equal although a decrease with frequency is expected. To explain this, we consider various profiles of snow grain size and density and predict their emissivity using a dense-medium radiative transfer (DMRT) model. The results show that the emissivities cannot be explained by constant profiles of grain size and density. Heterogeneous snowpacks need to be considered. We first test random variations of snow density and grain radius with depth and then monotonic and continuous variations in the snow grain radius. In both cases, we show that an overall increase of the snow grain radius with depth is required to match the observed emissivity in Antarctica. In addition, two parameters characterizing the snow grain profiles are retrieved and compared with (1) in situ measurements of grain size at various locations in East Antarctica, (2) grain size estimated using visible spaceborne radiometers and (3) a semi-empirical relationship for grain growth.
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Programme |
454 |
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Corporate Author |
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Thesis |
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Publisher |
International Glaciological Society |
Place of Publication |
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Editor |
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Language |
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Summary Language |
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Original Title |
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Series Editor |
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Series Title |
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Abbreviated Series Title |
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Series Volume |
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Series Issue |
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Edition |
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ISSN |
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ISBN |
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Medium |
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Area |
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Expedition |
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Notes |
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Approved |
yes |
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Call Number |
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Serial |
2067 |
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Author |
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Title |
Enhancement factors for grounded ice and ice shelves inferred from an anisotropic ice-flow model
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Type |
Journal Article |
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Year |
2010 |
Publication |
Journal Of Glaciology |
Abbreviated Journal |
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Volume |
56 |
Issue |
199 |
Pages |
805 -812 |
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Keywords |
glaciology, |
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Abstract |
Polar ice is known to be one of the most anisotropic natural materials. For a given fabric the polycrystal viscous response is strongly dependent on the actual state of stress and strain rate. Within an ice sheet, grounded-ice parts and ice shelves have completely different stress regimes, so one should expect completely different impacts of ice anisotropy on the flow. The aim of this work is to quantify, through the concept of enhancement factors, the influence of ice anisotropy on the flow of grounded ice and ice shelves. For this purpose, a full-Stokes anisotropic marine ice-sheet flowline model is used to compare isotropic and anisotropic diagnostic velocity fields on a fixed geometry. From these full-Stokes results, we propose a definition of enhancement factors for grounded ice and ice shelves, coherent with the asymptotic models used for these regions. We then estimate realistic values for the enhancement factors induced by ice anisotropy for grounded ice and ice shelves.
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Programme |
458 |
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Corporate Author |
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Thesis |
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Publisher |
International Glaciological Society |
Place of Publication |
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Series Issue |
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Edition |
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ISSN |
0022-1430 |
ISBN |
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Notes |
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Approved |
yes |
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Call Number |
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Serial |
2460 |
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Author |
Alemany O, Chappellaz J, Triest J, Calzas M, Cattani O, Chemin JF, Desbois Q, Desbois T, Duphil R, Falourd S, Grilli R, Guillerme C, Kerstel E, Laurent B, Lefebvre E, Marrocco N, Pascual O, Piard L, Possenti P, Romanini D, Thiebaut V, Yamani R, |
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Title |
The SUBGLACIOR drilling probe: concept and design
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Type |
Journal Article |
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Year |
2014 |
Publication |
Annals of Glaciology |
Abbreviated Journal |
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Volume |
55 |
Issue |
68 |
Pages |
233-242 |
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Keywords |
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Abstract |
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Programme |
1119 |
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Campaign |
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Corporate Author |
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Thesis |
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Publisher |
International Glaciological Society |
Place of Publication |
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Series Editor |
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Series Volume |
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Series Issue |
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Edition |
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ISSN |
0260-3055 |
ISBN |
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Notes |
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Approved |
yes |
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Call Number |
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Serial |
5931 |
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| Permanent link to this record |
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Author |
Duphil Romain, Possenti Philippe, Piard Luc, |
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Title |
A new leak-tight borehole casing at Dome Concordia station, Antarctica, for the SUBGLACIOR project
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Type |
Journal Article |
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Year |
2014 |
Publication |
Annals of Glaciology |
Abbreviated Journal |
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Volume |
55 |
Issue |
68 |
Pages |
351-354 |
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Keywords |
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Abstract |
In the frame of the SUBGLACIOR project, a new type of casing has been installed for testing during the 2013/14 austral summer season at Dome Concordia station, Antarctica. The SUBGLACIOR probe requires a full fluid column up to the surface, in order to circulate fluid for icechips recovery. This makes it essential that the casing is leak-tight through the porous firn column. We have evaluated existing solutions before opting to test a new method. This new system is made of polyethylene pipes which are welded together at the surface while the casing pipes are lowered into the reamed borehole. It is simple and lightweight and allows the casing to be installed quickly with
optimum chance of being leak-tight. The installed casing has been tested both with compressed air and drilling fluids and has proven to work. |
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Programme |
1119 |
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Corporate Author |
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Thesis |
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Publisher |
International Glaciological Society |
Place of Publication |
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Editor |
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Language |
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Summary Language |
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Original Title |
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Series Editor |
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Edition |
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ISSN |
02603055 |
ISBN |
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Notes |
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Approved |
yes |
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Call Number |
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Serial |
5932 |
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| Permanent link to this record |
