http://hdl.handle.net/2122/128 Sat, 25 May 2013 01:04:16 GMT 2013-05-25T01:04:16Z http://hdl.handle.net/2122/8576 Title: A synthesis of the Antarctic surface mass balance during the last 800 yr Authors: Frezzotti, M.; ENEA, Agenzia Nazionale per le nuove tecnologie, l’energia e lo sviluppo sostenibile, Rome, Italy; Scarchilli, C.; ENEA, Agenzia Nazionale per le nuove tecnologie, l’energia e lo sviluppo sostenibile, Rome, Italy; Becagli, S.; Department of Chemistry, University of Florence, Sesto F.no, Italy; Proposito, M.; ENEA, Agenzia Nazionale per le nuove tecnologie, l’energia e lo sviluppo sostenibile, Rome, Italy; Urbini, S.; Istituto Nazionale di Geofisica e Vulcanologia, Sezione Roma2, Roma, Italia Abstract: Global climate models suggest that Antarctic snowfall should increase in a warming climate and mitigate rises in the sea level. Several processes affect surface mass balance (SMB), introducing large uncertainties in past, present and future ice sheet mass balance. To provide an extended perspective on the past SMB of Antarctica, we used 67 firn/ice core records to reconstruct the temporal variability in the SMB over the past 800 yr and, in greater detail, over the last 200 yr. Our SMB reconstructions indicate that the SMB changes over most of Antarctica are statistically negligible and that the current SMB is not exceptionally high compared to the last 800 yr. High-accumulation periods have occurred in the past, specifically during the 1370s and 1610s. However, a clear increase in accumulation of more than 10% has occurred in high SMB coastal regions and over the highest part of the East Antarctic ice divide since the 1960s. To explain the differences in behaviour between the coastal/ice divide sites and the rest of Antarctica, we suggest that a higher frequency of blocking anticyclones increases the precipitation at coastal sites, leading to the advection of moist air in the highest areas, whereas blowing snow and/or erosion have significant negative impacts on the SMB at windy sites. Eight hundred years of stacked records of the SMB mimic the total solar irradiance during the 13th and 18th centuries. The link between those two variables is probably indirect and linked to a teleconnection in atmospheric circulation that forces complex feedback between the tropical Pacific and Antarctica via the generation and propagation of a large-scale atmospheric wave train. Tue, 19 Feb 2013 23:00:00 GMT http://hdl.handle.net/2122/8576 2013-02-19T23:00:00Z http://hdl.handle.net/2122/8533 Title: Bedmap2: improved ice bed, surface and thickness datasets for Antarctica Authors: Fretwell, P.; British Antarctic Survey, Cambridge, UK; Pritchard, H. D.; British Antarctic Survey, Cambridge, UK; Vaughan, D. G.; British Antarctic Survey, Cambridge, UK; Bamber, J. L.; School of Geographical Sciences, University of Bristol, UK; Barrand, N. E.; British Antarctic Survey, Cambridge, UK; Bell, R.; Lamont-Doherty Earth Observatory of Columbia University, Palisades, USA; Bianchi, C.; Istituto Nazionale di Geofisica e Vulcanologia, Sezione Roma2, Roma, Italia; Bingham, R. G.; School of Geosciences, University of Aberdeen, UK; Blankenship, D. D.; Institute for Geophysics, University of Texas at Austin, USA; Casassa, G.; Centro de Estudios Cientificos, Santiago, Chile; Catania, G.; Institute for Geophysics, University of Texas at Austin, USA; Callens, D.; Laboratoire de Glaciologie, Universit´e Libre de Bruxelles, Brussels, Belgium; Conway, H.; Earth and Space Sciences, University of Washington, Seattle, USA; Cook, A. J.; Department of Geography, Swansea University, Swansea, UK; Corr, H. F. J.; British Antarctic Survey, Cambridge, UK; Damaske, D.; Federal Institute for Geosciences and Natural Resources, Hannover, Germany; Damm, V.; Federal Institute for Geosciences and Natural Resources, Hannover, Germany; Ferraccioli, F.; British Antarctic Survey, Cambridge, UK; Forsberg, R.; National Space Institute, Technical University of Denmark, Denmark; Fujita, S.; National Institute of Polar Research, Tokyo, Japan; Gim, Y.; Jet Propulsion Laboratory. California Institute of Technology, Pasadena, USA; Gogineni, P.; Electrical Engineering & Computer Science, University of Kansas, Lawrence, USA; Griggs, J. A.; School of Geographical Sciences, University of Bristol, UK; Hindmarsh, R. C. A.; British Antarctic Survey, Cambridge, UK; Holmlund, P.; Stockholm University, Stockholm, Sweden; Holt, J. W.; Institute for Geophysics, University of Texas at Austin, USA; Jacobel, R. W.; St. Olaf College, Northfield, MN 55057, USA; Jenkins, A.; British Antarctic Survey, Cambridge, UK; Jokat, W.; Alfred Wegener Institute, Bremerhaven, Germany; Jordan, T.; British Antarctic Survey, Cambridge, UK; King, E. C.; British Antarctic Survey, Cambridge, UK; Kohler, J.; Norwegian Polar Institute, Fram Centre, Tromsø, Norway; Krabill, W.; NASA Wallops Flight Facility, Virginia, USA; Riger-Kusk, M.; College of Science, University of Canterbury, Christchurch, New Zealand; Langley, K. A.; Department of Geosciences, University of Oslo, Norway; Leitchenkov, G.; Institute for Geology and Mineral Resources of the World Ocean, St.-Petersburg, Russia; Leuschen, C.; Electrical Engineering & Computer Science, University of Kansas, Lawrence, USA; Luyendyk, B. P.; Earth Research Institute, University of California in Santa Barbara, USA; Matsuoka, K.; Norwegian Polar Institute, Tromso, Norway; Mouginot, J.; Department of Earth System Science, University of California, Irvine, USA; Nitsche, F. O.; Lamont-Doherty Earth Observatory of Columbia University, Palisades, USA; Nogi, Y.; National Institute of Polar Research, Tokyo, Japan; Nost, O. A.; Norwegian Polar Institute, Tromso, Norway; Popov, S. V.; Polar Marine Geosurvey Expedition, St.-Petersburg, Russia; Rignot, E.; School of Physical Sciences, University of California, Irvine, USA; Rippin, D. M.; Environment Department, University of York, Heslington, York, YO10 5DD, UK; Rivera, A.; Centro de Estudios Cientificos, Santiago, Chile; Roberts, J.; Department of Sustainability, Environment, Water, Population and Communities, Australian Antarctic Division, Hobart, Tasmania, Australia; Ross, N.; School of Geography, Politics and Sociology, Newcastle University, Newcastle upon Tyne, NE1 7RU, UK; Siegert, M. J.; School of Geographical Sciences, University of Bristol, UK; Smith, A. M.; British Antarctic Survey, Cambridge, UK; Steinhage, D.; Alfred Wegener Institute, Bremerhaven, Germany; Studinger, M.; NASA Goddard Space Flight Center, Greenbelt, USA; Sun, B.; Polar Research Institute of China, Shanghai, China; Tinto, B. K.; Lamont-Doherty Earth Observatory of Columbia University, Palisades, USA; Welch, B. C.; Alfred Wegener Institute, Bremerhaven, Germany; Wilson, D.; Institute for Crustal Studies, University of California in Santa Barbara, USA; Young, D. A.; Institute for Geophysics, University of Texas at Austin, USA; Xiangbin, C.; Polar Research Institute of China, Shanghai, China; Zirizzotti, A.; Istituto Nazionale di Geofisica e Vulcanologia, Sezione Roma2, Roma, Italia Abstract: We present Bedmap2, a new suite of gridded products describing surface elevation, ice-thickness and the seafloor and subglacial bed elevation of the Antarctic south of 60 S. We derived these products using data from a variety of sources, including many substantial surveys completed since the original Bedmap compilation (Bedmap1) in 2001. In particular, the Bedmap2 ice thickness grid is made from 25 million measurements, over two orders of magnitude more than were used in Bedmap1. In most parts of Antarctica the subglacial landscape is visible in much greater detail than was previously available and the improved datacoverage has in many areas revealed the full scale of mountain ranges, valleys, basins and troughs, only fragments of which were previously indicated in local surveys. The derived statistics for Bedmap2 show that the volume of ice contained in the Antarctic ice sheet (27 million km3) and its potential contribution to sea-level rise (58 m) are similar to those of Bedmap1, but the mean thickness of the ice sheet is 4.6% greater, the mean depth of the bed beneath the grounded ice sheet is 72m lower and the area of ice sheet grounded on bed below sea level is increased by 10 %. The Bedmap2 compilation highlights several areas beneath the ice sheet where the bed elevation is substantially lower than the deepest bed indicated by Bedmap1. These products, along with grids of data coverage and uncertainty, provide new opportunities for detailed modelling of the past and future evolution of the Antarctic ice sheets. Mon, 31 Dec 2012 23:00:00 GMT http://hdl.handle.net/2122/8533 2012-12-31T23:00:00Z http://hdl.handle.net/2122/8498 Title: Extent of low-accumulation ‘wind glaze’ areas on the East Antarctic plateau: implications for continental ice mass balance Authors: Scambos, T. A.; National Snow and Ice Data Center, University of Colorado, Boulder, Boulder, CO, USA; Frezzotti, M.; ENEA-CRE, Casaccia, Rome, Italy; Haran, T.; National Snow and Ice Data Center, University of Colorado, Boulder, Boulder, CO, USA; Bohlander, J.; National Snow and Ice Data Center, University of Colorado, Boulder, Boulder, CO, USA; Lenaerts, J. T. M.; Institute for Marine and Atmospheric Research, Utrecht University, Utrecht, The Netherlands; Van Den Broeke, M. R.; Institute for Marine and Atmospheric Research, Utrecht University, Utrecht, The Netherlands; Jezek, K.; Byrd Polar Research Center, The Ohio State University, Columbus, OH, USA; Long, D.; Department of Electrical Engineering, Brigham Young University, Provo, UT, USA; Urbini, S.; Istituto Nazionale di Geofisica e Vulcanologia, Sezione Roma2, Roma, Italia; Farness, K.; Byrd Polar Research Center, The Ohio State University, Columbus, OH, USA; Neumann, T.; NASA Goddard Space Flight Center, Greenbelt, MD, USA; Albert, M.; Thayer School of Engineering, Dartmouth College, Hanover, NH, USA; Winther, J.-G.; Norwegian Polar Institute, Tromsø, Norway Abstract: Persistent katabatic winds form widely distributed localized areas of near-zero net surface accumulation on the East Antarctic ice sheet (EAIS) plateau. These areas have been called ‘glaze’ surfaces due to their polished appearance. They are typically 2–200km2 in area and are found on leeward slopes of ice-sheet undulations and megadunes. Adjacent, leeward high-accumulation regions (isolated dunes) are generally smaller and do not compensate for the local low in surface mass balance (SMB). We use a combination of satellite remote sensing and field-gathered datasets to map the extent of wind glaze in the EAIS above 1500m elevation. Mapping criteria are derived from distinctive surface and subsurface characteristics of glaze areas resulting from many years of intense annual temperature cycling without significant burial. Our results show that 11.2 1.7%, or 950 143 103 km2, of the EAIS above 1500m is wind glaze. Studies of SMB interpolate values across glaze regions, leading to overestimates of net mass input. Using our derived wind-glaze extent, we estimate this excess in three recent models of Antarctic SMB at 46–82 Gt. The lowest-input model appears to best match the mean in regions of extensive wind glaze. Tue, 31 Jul 2012 22:00:00 GMT http://hdl.handle.net/2122/8498 2012-07-31T22:00:00Z http://hdl.handle.net/2122/7248 Title: Getting around Antarctica: new high-resolution mappings of the grounded and freely-floating boundaries of the Antarctic ice sheet created for the International Polar Year Authors: Bindschadler, R.; Code 614.0, NASA Goddard Space Flight Center, Greenbelt, MD 20771, USA; Choi, H.; SAIC, NASA Goddard Space Flight Center, Greenbelt MD 20771, USA; Wichlacz, A.; SAIC, NASA Goddard Space Flight Center, Greenbelt MD 20771, USA; Bingham, R.; School of Geosciences, University of Aberdeen, Aberdeen, AB24 3FX, UK; Bohlander, J.; National Snow and Ice Data Center, University of Colorado, Boulder CO 80309-0449, USA; Brunt, K.; Code 614.1, NASA Goddard Space Flight Center, Greenbelt MD 20771, USA; Corr, H.; British Antarctic Survey, High Cross, Madingley Road, Cambridge, CB3 0ET, UK; Drews, R.; Alfred Wegener Institut for Polar and Marine Research, Postfach 12 01 61, 27515 Bremerhaven, Germany; Fricker, H.; Scripps Institute of Oceanography, University of California at San Diego, 9500 Giman Drive, La Jolla CA 92093, USA; Hall, M.; Climate Change Institute, University of Maine, Orono ME 04469, USA; Hindmarsh, R.; British Antarctic Survey, High Cross, Madingley Road, Cambridge, CB3 0ET, UK; Kohler, J.; Norwegian Polar Institute, Polar Environmental Centre, 9296 Tromso, Norway; Padman, L.; Earth and Space Research (ESR), 3350 SW Cascade Ave., Corvallis, OR 97333-1536, USA; Rack, W.; Gateway Antarctica, University of Canterbury, Private Bag, Christchurch 8140, New Zealand; Rotschky, G.; Norwegian Polar Institute, Polar Environmental Centre, 9296 Tromso, Norway; Urbini, S.; Istituto Nazionale di Geofisica e Vulcanologia, Sezione Roma2, Roma, Italia; Vornberger, P.; SAIC, NASA Goddard Space Flight Center, Greenbelt MD 20771, USA; Young, N.; Australian Antarctic Division, University of Tasmania, Kingston, Tasmania 7050, Australia Abstract: Two ice-dynamic transitions of the Antarctic ice sheet – the boundary of grounded ice features and the freelyfloating boundary – are mapped at 15-m resolution by participants of the International Polar Year project ASAID using customized software combining Landsat-7 imagery and ICESat/GLAS laser altimetry. The grounded ice boundary is 53 610 km long; 74% abuts to floating ice shelves or outlet glaciers, 19% is adjacent to open or sea-ice covered ocean, and 7% of the boundary ice terminates on land. The freelyfloating boundary, called here the hydrostatic line, is the most landward position on ice shelves that expresses the full amplitude of oscillating ocean tides. It extends 27 521 km and is discontinuous. Positional (one-sigma) accuracies of the grounded ice boundary vary an order of magnitude ranging from ±52m for the land and open-ocean terminating segments to ±502m for the outlet glaciers. The hydrostatic line is less well positioned with errors over 2 km. Elevations along each line are selected from 6 candidate digital elevation models based on their agreement with ICESat elevation values and surface shape inferred from the Landsat imagery. Elevations along the hydrostatic line are converted to ice thicknesses by applying a firn-correction factor and a flotation criterion. BEDMAP-compiled data and other airborne data are compared to the ASAID elevations and ice thicknesses to arrive at quantitative (one-sigma) uncertainties of surface elevations of ±3.6, ±9.6, ±11.4, ±30 and ±100m for five ASAID-assigned confidence levels. Over one-half of the surface elevations along the grounded ice boundary and over one-third of the hydrostatic line elevations are ranked in the highest two confidence categories. A comparison between ASAID-calculated ice shelf thicknesses and BEDMAP-compiled data indicate a thin-ice bias of 41.2±71.3m for the ASAID ice thicknesses. The relationship between the seaward offset of the hydrostatic line from the grounded ice boundary only weakly matches a prediction based on beam theory. The mapped products along with the customized software to generate them and a variety of intermediate products are available from the National Snow and Ice Data Center. Thu, 30 Jun 2011 22:00:00 GMT http://hdl.handle.net/2122/7248 2011-06-30T22:00:00Z http://hdl.handle.net/2122/6967 Title: Mass balance of Campbell Glacier (Northern Victoria Land, Antarctica) : preliminary analysis Authors: Mancini, M.; Frezzotti, M.; Smiraglia, C.; Gragnani, R.; Zirizzotti, A.; Istituto Nazionale di Geofisica e Vulcanologia, Sezione Roma2, Roma, Italia; Motta, M.; Pavan, M. Abstract: This study aims to estimate the mass balance of Campbell Glacier(norhern Victoria Land East Antarctica). Tue, 31 Dec 2002 23:00:00 GMT http://hdl.handle.net/2122/6967 2002-12-31T23:00:00Z http://hdl.handle.net/2122/6966 Title: Ice discharge of eastern Dome C drainage area, Antarctica, determined from airborne radar survey and satellite image analysis Authors: Frezzotti, M.; Tabacco, I. E.; Zirizzotti, A.; Istituto Nazionale di Geofisica e Vulcanologia, Sezione Roma2, Roma, Italia Abstract: Eastern Dome C, southern Talos Dome and northern Taylor Dome are drained by the Priestley, Reeves, David, Mawson and Mackay outlet glaciers, which flow into the Scott Coast on the west side of the Ross Sea, Antarctica. Airborne radar surveys were conducted on these glaciers to determine ice thickness and bed morphology along transverse and longitudinal profiles of the grounded and floating segments. A new analysis of a Landsat Thematic Mapper satellite image using a tracking technique was used to measure ice velocity at grounding lines and along ice tongues. The integration of radar and satellite data helped to locate grounding lines and to calculate the ice discharge. Changes in ice fluxes of floating glaciers were used to determine basal melting and freezing rates. The ice discharge calculated is less than half that required for a zero net surface mass balance according to the inputs given by the accumulation estimates widely adopted at present. The basal melting rates of meteoric ice represent 50% of the net ablation rate. Tue, 29 Feb 2000 23:00:00 GMT http://hdl.handle.net/2122/6966 2000-02-29T23:00:00Z http://hdl.handle.net/2122/4066 Title: Snow dunes and glazed surfaces in Antarctica: new field and remote-sensing data Authors: Frezzotti, M.; ENEA, Centro Ricerche Casaccia, P.O. Box 2400, I-00100 Rome, Italy; Gandolfi, S.; DISTART, Università di Bologna, Viale Risorgimento 2, I-40136 Bologna, Italy; La Marca, F.; Dipartimento di ICMMPM, Università di Roma "La Sapienza", Via Eudossiana 18, I-00184 Rome, Italy; Urbini, S.; Istituto Nazionale di Geofisica e Vulcanologia, Sezione Roma2, Roma, Italia Abstract: As part of the International Trans-Antarctic Scientific Expedition project, the Italian Antarctic Programme undertook two traverses from the Terra Nova station to Talos Dome and to Dome C. Along the traverses, the party carried out several tasks (drilling, glaciological and geophysical exploration). The difference in spectral response between glazed surfaces and snow makes it simple to identify these areas on visible/near-infrared satellite images. Integration of field observation and remotely sensed data allows the description of different mega-morphologic features: wide glazed surfaces, sastrugy glazed surface fields, transverse dunes and megadunes. Topography global positioning system, ground penetrating radar and detailed snow-surface surveys have been carried out, providing new information about the formation and evolution of mega-morphologic features. The extensive presence, (up to 30%) of glazed surface caused by a long hiatus in accumulation, with an accumulation rate of nil or slightly negative, has a significant impact on the surface mass balance of a wide area of the interior part of East Antarctica. The aeolian processes creating these features have important implications for the selection of optimum sites for ice coring, because orographic variations of even a few metres per kilometre have a significant impact on the snow-accumulation process. Remote-sensing surveys of aeolian macro-morphology provide a proven, high-quality method for detailed mapping of the interior of the ice sheet's prevalent wind direction and could provide a relative indication of wind intensity. Mon, 31 Dec 2001 23:00:00 GMT http://hdl.handle.net/2122/4066 2001-12-31T23:00:00Z http://hdl.handle.net/2122/4065 Title: A New Bedrock Map of the Dome C Area Authors: Forieri, A.; Università degli Studi di Milano, Sezione Geofisica, via Cicognara 7, 1-20129 Milano - Italy and Dipartimento di Scienze della Terra, Università di Siena, Via del Laterino 8, 53100 Siena - Italy; Tabacco, I. E.; Università degli Studi di Milano, Sezione Geofisica, via Cicognara 7, 1-20129 Milano - Italy; Della Vedova, A.; Università degli Studi di Milano, Sezione Geofisica, via Cicognara 7, 1-20129 Milano - Italy; Zirizzotti, A.; Istituto Nazionale di Geofisica e Vulcanologia, Sezione Roma2, Roma, Italia; Bianchi, C.; Istituto Nazionale di Geofisica e Vulcanologia, Sezione Roma2, Roma, Italia; De Michelis, P.; Istituto Nazionale di Geofisica e Vulcanologia, Sezione Roma2, Roma, Italia; Passerini, A.; Università degli Studi di Milano Bicocca, Piazza della Scienza 1, 1-20126 Milano - Italy Editors: Frezzotti, M.; ENEA Progetto Clima, PO Box 2400, 000100 Roma AD - Italy; Maggi, V.; Department of Environmental Sciences, University of Milano–Bicocca, Piazza della Scienza 1, I-20126 Milan, Italy Abstract: A large number of airborne and ground-based radar echo sounding (RES) data were collected in the Dome C - Vostok region during the Italian Antarctic expeditions in 1995, 1997, 1999 and 2001. Tabacco et al. (1998) used the 1995 data to produce a topographic map of Dome C. We present a new map of bed topography based on all collected radar data. Tue, 31 Dec 2002 23:00:00 GMT http://hdl.handle.net/2122/4065 2002-12-31T23:00:00Z http://hdl.handle.net/2122/4064 Title: Un karst sous la glace de l'Antarctide ? Authors: Bini, A.; Università degli Studi di Milano, Sez. Geologia, Via Mangiagalli 34, I-20133 Milan, Italy; Forieri, A.; Università degli Studi di Siena, Dip. Scienze della Terra, Via del Laterino 8, I-53100 Siena, Italy; Remy, F.; Laboratoire d’Etudes en Géophysique et Océanographie Spatiales, 18 av. Edouard Belin, 31055 Toulouse Cedex, France; Tabacco, I. E.; Università degli Studi di Milano, Sez. Geofisica, Via Cicognara 7, I-20129 Milan, Italy; Zirizzotti, A.; Istituto Nazionale di Geofisica e Vulcanologia, Sezione Roma2, Roma, Italia; Zuccoli, L.; Università degli Studi di Milano, Sez. Geologia, Via Mangiagalli 34, I-20133 Milan, Italy Abstract: A new bedrock map of the Dome C area based on all radar data collected during Italian Antarctic Expeditions in 1995, 1997, 1999 and 2001 is presented. The map can clearly distinguish the Dome C plateau, along with some valleys and ridges develop. The plateau develops at three different altimetric levels and its morphology is characterized by hills and closed depressions. There are no visible features which can be ascribed to glacial erosion or deposition. The major valley is 15km wide and 500m deep; its axis is parallel to that of other valleys and ridges in the plateau. The valley bottom is not flat, but contains a saddle in its centre. The morphology of the major valley could be considered as a relict one which was not modified by the overlying ice cap. Two big ridges, characterized by hills, saddles and depressions, lie near the boundaries of the area. The hill and depression landscape may be the results of two different processes the weathering of granitic rocks, with the development of a "Wemi-oranges" and inselberg landscape, or the karstification of limestones, and development of a cone karst. The karstic hypothesis should be the more suitable, but it is impossible to exclude the granitic rock weathering. Both proposed genetic hypotheses call for a warm humide climate and a long period of stability in a continental environment. Consequently, the ice cap did not largely modified the landscape. Tue, 31 Dec 2002 23:00:00 GMT http://hdl.handle.net/2122/4064 2002-12-31T23:00:00Z http://hdl.handle.net/2122/4063 Title: Evidence of 14 New Subglacial Lakes in the Dome C-Vostok Area Authors: Tabacco, I. E.; Università degli Studi di Milano, Sezione Geofisica, Via Cicognara 7, 20129 Milano - Italy; Forieri, A.; Università degli Studi di Milano, Sezione Geofisica, Via Cicognara 7, 20129 Milano - Italy and Dipartimento di Scienze della Terra, Università di Siena, Via del Laterino 8, 53100 Siena - Italy; Della Vedova, A.; Università degli Studi di Milano, Sezione Geofisica, Via Cicognara 7, 20129 Milano - Italy; Zirizzotti, A.; Istituto Nazionale di Geofisica e Vulcanologia, Sezione Roma2, Roma, Italia; Bianchi, C.; Istituto Nazionale di Geofisica e Vulcanologia, Sezione Roma2, Roma, Italia; De Michelis, P.; Istituto Nazionale di Geofisica e Vulcanologia, Sezione Roma2, Roma, Italia; Passerini, A.; Università degli Studi di Milano Bicocca, Piazza della Scienza 1 , 20126 Milano - Italy Editors: Frezzotti, M.; ENEA Progetto Clima, PO Box 2400, 000100 Roma AD - Italy; Maggi, V.; Department of Environmental Sciences, University of Milano–Bicocca, Piazza della Scienza 1, I-20126 Milan, Italy Abstract: In the last few years subglacial lakes have been of great interest to the scientific community for various reasons. The lakes could be an unknown extreme habitat, which have been isolated from the terrestrial biosphere for a long time. They may have formed before the ice sheet and could perhaps reveal environmental conditions prior to its formation. Lastly, they may play a role in the current dynamics of the ice sheet. Strong radar reflections from the base of the ice sheet can generally be ascribed to either water-saturated basal sediments or subglacial lakes (Oswald & Robin, 1973). Based on radar data alone, the identification of lakes is possible if other features are present: flat and quite horizontal reflectors with nearly constant echo intensity and sharp edges similar to the margins of a catchment basin (Siegert et al., 1996; Siegert & Ridley, 1998; German & Siegert, 1999; Siegert, 2000; Tabacco et al., 2002). Subglacial lakes can be expressed in the overlying ice sheet as extremely flat surfaces with respect to the surrounding slopes (Ridley et al., 1993; Kapitsa et &l996 ; Siegert & Ridley,1998; Tabacco et al., 2002). To date, about 70 lakes have been discovered in all of Antarctica (Siegert et al.,1996); 21 of these are located in the Dome C-Vostok region. Tue, 31 Dec 2002 23:00:00 GMT http://hdl.handle.net/2122/4063 2002-12-31T23:00:00Z