http://hdl.handle.net/2122/122 2013-05-24T03:43:25Z 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. 2012-07-31T22:00:00Z http://hdl.handle.net/2122/5120 Title: Obliquity-paced Pliocene West Antarctic ice sheet oscillations Authors: Naish, T.; Antarctic Research Centre, Victoria University of Wellington, Kelburn Parade, PO Box 600, Wellington 6012, New Zealand; Powell, R.; Department of Geology & Environmental Geosciences, Northern Illinois University, DeKalb, Illinois 60115, USA.; Levy, R.; ANDRILL Science Management Office, Department of Geosciences, University of Nebraska-Lincoln, Lincoln, Nebraska 68588-0340, USA; Wilson, G.; University of Otago, Department of Geology, PO Box 56, Leith Street, Dunedin, Otago 9001, New Zealand; Scherer, R.; Department of Geology & Environmental Geosciences, Northern Illinois University, DeKalb, Illinois 60115, USA.; Talarico, F.; Universita` di Siena, Dipartimento di Scienze delle Terra, Via Laterina 8, I-53100 Siena, Italy; Krissek, L.; Ohio State University, Department of Geological Sciences, 275 Mendenhall Lab, 125 South Oval Mall, Columbus, Ohio 43210, USA; Niessen, F.; Alfred Wegener Institute, Department of Geosciences, Postfach 12 01 6, Am Alten Hafen 26, D-27515 Bremerhaven, Germany; Pompilio, M.; Istituto Nazionale di Geofisica e Vulcanologia, Sezione Pisa, Pisa, Italia; Wilson, T.; Ohio State University, Department of Geological Sciences, 275 Mendenhall Lab, 125 South Oval Mall, Columbus, Ohio 43210, USA; Carter, L.; Antarctic Research Centre, Victoria University of Wellington, Kelburn Parade, PO Box 600, Wellington 6012, New Zealand; DeConto, R.; Department of Geosciences, 233 Morrell Science Centre, University of Massachusetts, Amherst, Massachusetts 01003-9297, USA; Huybers, P.; Department of Earth and Planetary Sciences, Harvard University, Massachusetts 02138, USA; Mckay, R.; Antarctic Research Centre, Victoria University of Wellington, Kelburn Parade, PO Box 600, Wellington 6012, New Zealand; Pollard, D.; Earth and Environmental Systems Institute, Pennsylvania State University, University Park, Pennsylvania 16802, USA; Ross, J.; New Mexico Institute of Mining & Technology, Earth & Environmental Sciences, Socorro, New Mexico 87801, USA; Winter, D.; ANDRILL Science Management Office, Department of Geosciences, University of Nebraska-Lincoln, Lincoln, Nebraska 68588-0340, USA; Barrett, P.; Antarctic Research Centre, Victoria University of Wellington, Kelburn Parade, PO Box 600, Wellington 6012, New Zealand; Browne, G.; GNS Science, 1 Fairway Drive, PO Box 30-368, Lower Hutt 5040, New Zealand; Cody, R.; Antarctic Research Centre, Victoria University of Wellington, Kelburn Parade, PO Box 600, Wellington 6012, New Zealand; Cowan, E.; Department of Geology, Appalachian State University, ASU Box 32067, Boone, North Carolina 28608-2067, USA; Crampton, J.; GNS Science, 1 Fairway Drive, PO Box 30-368, Lower Hutt 5040, New Zealand; Dunbar, G.; Antarctic Research Centre, Victoria University of Wellington, Kelburn Parade, PO Box 600, Wellington 6012, New Zealand; Florindo, F.; Istituto Nazionale di Geofisica e Vulcanologia, Sezione Roma2, Roma, Italia; Gebhardt, C.; Alfred Wegener Institute, Department of Geosciences, Postfach 12 01 6, Am Alten Hafen 26, D-27515 Bremerhaven, Germany; Graham, I.; GNS Science, 1 Fairway Drive, PO Box 30-368, Lower Hutt 5040, New Zealand; Hannah, M.; Antarctic Research Centre, Victoria University of Wellington, Kelburn Parade, PO Box 600, Wellington 6012, New Zealand; Hansaraj, D.; Antarctic Research Centre, Victoria University of Wellington, Kelburn Parade, PO Box 600, Wellington 6012, New Zealand; Harwood, D.; ANDRILL Science Management Office, Department of Geosciences, University of Nebraska-Lincoln, Lincoln, Nebraska 68588-0340, USA; Helling, D.; Alfred Wegener Institute, Department of Geosciences, Postfach 12 01 6, Am Alten Hafen 26, D-27515 Bremerhaven, Germany; Henrys, S.; GNS Science, 1 Fairway Drive, PO Box 30-368, Lower Hutt 5040, New Zealand; Hinnov, L.; Department of Earth and Planetary Sciences, Johns Hopkins University, Baltimore, Maryland 21218, USA; Kuhn, G.; Alfred Wegener Institute, Department of Geosciences, Postfach 12 01 6, Am Alten Hafen 26, D-27515 Bremerhaven, Germany; Kyle, P.; New Mexico Institute of Mining & Technology, Earth & Environmental Sciences, Socorro, New Mexico 87801, USA; Laüfer, A.; Federal Institute of Geosciences & Natural Resources, BGR, Stilleweg 2, D-30655 Hannover, Germany; Maffioli, P.; Universita` Milano-Bicocca, Dipartimento di Scienze Geologiche e Geotecnologie, Piazza della Scienza 4, I-20126 Milano, Italy; Magens, D.; Alfred Wegener Institute, Department of Geosciences, Postfach 12 01 6, Am Alten Hafen 26, D-27515 Bremerhaven, Germany; Mandernack, K.; Colorado School of Mines, Department of Chemistry & Geochemistry, 1500 Illinois Street, Golden, Colorado 80401, USA; McIntosh, W.; New Mexico Institute of Mining & Technology, Earth & Environmental Sciences, Socorro, New Mexico 87801, USA; Millan, C.; Ohio State University, Department of Geological Sciences, 275 Mendenhall Lab, 125 South Oval Mall, Columbus, Ohio 43210, USA; Morin, R.; US Geological Survey, Mail Stop 403, Denver Federal Center, Denver, Colorado 80225, USA; Ohneiser, C.; University of Otago, Department of Geology, PO Box 56, Leith Street, Dunedin, Otago 9001, New Zealand; Paulsen, T.; University of Wisconsin-Oshkosh, Department of Geology, 800 Algoma Boulevard, Oshkosh, Wisconsin 54901, USA; Persico, D.; Dipartimento di Scienze della Terra, Universita` degli Studi di Parma, Via Usberti 157/A, I-43100 Parma, Italy; Raine, I.; GNS Science, 1 Fairway Drive, PO Box 30-368, Lower Hutt 5040, New Zealand; Reed, J.; CHRONOS, Iowa State University, Department of Geological & Atmospheric Sciences, 275 Science I, Ames, Iowa 50011-3212, USA; Riesselman, C.; Department of Geological and Environmental Sciences, School of Earth Sciences, Stanford University, Stanford, California 94305, USA; Sagnotti, L.; Istituto Nazionale di Geofisica e Vulcanologia, Sezione Roma2, Roma, Italia; Schmitt, D.; Department of Physics, Mailstop #615, University of Alberta, Edmonton, Alberta T6G 2G7, Canada; Sjunneskog, C.; Department of Geology and Geophysics, Louisiana State University, Baton Rouge, Louisiana 70803, USA; Strong, P.; GNS Science, 1 Fairway Drive, PO Box 30-368, Lower Hutt 5040, New Zealand; Taviani, M.; CNR, ISMAR – Bologna, Via Gobetti 101, I-40129 Bologna, Italy; Vogel, S.; Department of Geology & Environmental Geosciences, Northern Illinois University, DeKalb, Illinois 60115, USA.; Wilch, T.; Albion College, Department of Geology, Albion, Michigan 49224, USA; Williams, T.; Columbia University, Lamont-Doherty Earth Observatory, Palisades, New York 10964, USA Abstract: Thirty years after oxygen isotope records frommicrofossils deposited in ocean sediments confirmed the hypothesis that variations in the Earth’s orbital geometry control the ice ages1, fundamental questions remain over the response of the Antarctic ice sheets to orbital cycles2. Furthermore, an understanding of the behaviour of the marine-based West Antarctic ice sheet (WAIS) during the ‘warmer-than- present’ early-Pliocene epoch (̃5–3Myr ago) is needed to better constrain the possible range of ice-sheet behaviour in the context of future global warming3. Here we present a marine glacial record from the upper 600 m of theAND-1B sediment core recovered from beneath the northwest part of the Ross ice shelf by the ANDRILL programme and demonstrate well-dated, ̃40-kyr cyclic variations in ice-sheet extent linked to cycles in insolation influenced by changes in the Earth’s axial tilt (obliquity) during the Pliocene. Our data provide direct evidence for orbitally induced oscillations in the WAIS, which periodically collapsed, resulting in a switch from grounded ice, or ice shelves, to open waters in the Ross embayment when planetary temperatures were up to ̃3 C warmer than today4 and atmospheric CO2 concentration was as high as ̃400 p.p.m.v. (refs 5, 6). The evidence is consistent with a new ice-sheet/ice-shelf model7 that simulates fluctuations in Antarctic ice volume of up to + 7 m in equivalent sea level associated with the loss of the WAIS and up to +3 m in equivalent sea level from the EastAntarctic ice sheet, in response to ocean-induced melting paced by obliquity.During interglacial times, diatomaceous sediments indicate high surface-water productivity, minimal summer sea ice and air temperatures above freezing, suggesting an additional influence of surface melt8 under conditions of elevated CO2. 2009-03-18T23:00:00Z http://hdl.handle.net/2122/4082 Title: Analysis of bottom morphology of the David Glacier-Drygalski Ice Tongue, East Antarctica Authors: Tabacco, I. E.; Sezione Geofisica, Dipartimento di Science della Terra, Università degli Studi di Milano, I-20129 Milano, Italy; Bianchi, C.; Istituto Nazionale di Geofisica e Vulcanologia, Sezione Roma2, Roma, Italia; Chiappini, M.; Istituto Nazionale di Geofisica e Vulcanologia, Sezione Roma2, Roma, Italia; Zirizzotti, A.; Istituto Nazionale di Geofisica e Vulcanologia, Sezione Roma2, Roma, Italia; Zuccheretti, E.; Istituto Nazionale di Geofisica e Vulcanologia, Sezione Roma2, Roma, Italia Abstract: Data from radio-sounding measurements have been analysed to determine the ice thickness and the bottom morphology of Drygalski Ice Tongue, Antarctica. The morphology and the structure of the bottom surface has been studied through an electromagnetic interpretation. A function that includes the gain/loss due to the geometrical shape of the reflecting surfaces has been calculated. Such a function has been evaluated assuming some physical electromagnetic quantities (the temperature of the glacier, the complex dielectric permittivity of ice, sea ice and sea water). The ice-water interface shows both concave and convex faces toward the sounding system, producing a focusing or defocusing effect, detected as absolute (or relative) amplitude variation in the echo signal. It is shown that the calculated function follows quite well the observed bottom rippled surface of the glacier tongue estimated from the time-arrival measurements of the echo signal. 1999-12-31T23:00:00Z http://hdl.handle.net/2122/4011 Title: Five subglacial lakes and one of Antarctica's thickest ice covers newly determined by radio echo sounding over the Vostok-Dome C region Authors: Cafarella, L.; Istituto Nazionale di Geofisica e Vulcanologia, Sezione Roma2, Roma, Italia; Urbini, S.; Istituto Nazionale di Geofisica e Vulcanologia, Sezione Roma2, Roma, Italia; Bianchi, C.; Istituto Nazionale di Geofisica e Vulcanologia, Sezione Roma2, Roma, Italia; Zirizzotti, A.; Istituto Nazionale di Geofisica e Vulcanologia, Sezione Roma2, Roma, Italia; Tabacco, I. E.; Dip. Science della Terra, Sez. Geofisica, Via Cicognara 7, 20129 Milan, Italy; Forieri, A.; Dip. Science della Terra, Sez. Geofisica, Via Cicognara 7, 20129 Milan, Italy Abstract: Radio echo sounding (RES) measurements were collected from 1995 to 2003 during Italian Antarctic expeditions over the Vostok-Dome C region. The data collected allow for the reconstruction of a bedrock elevation map between the Belgica Highlands and the Aurora Subglacial Basin (112.0° - 124.0°E 74.0° - 78.0°S). Moreover, analysis of the RES data has revealed one of the thickest ice covers in Antarctica (4755 ± 16 m; 118.321°E, 76.059°S) as well as five new subglacial lakes. 2005-12-31T23:00:00Z http://hdl.handle.net/2122/4008 Title: Italian RES Investigation in Antarctica: The New Radar System Authors: Tabacco, I. E.; Dip. Scienze della Terra, Sez. Geofisica, Via Cicognara 2, Milano - Italy; Bianchi, C.; Istituto Nazionale di Geofisica e Vulcanologia, Sezione Roma2, Roma, Italia; Baskaradas, J. A.; Istituto Nazionale di Geofisica e Vulcanologia, Sezione Roma2, Roma, Italia; Cafarella, L.; Istituto Nazionale di Geofisica e Vulcanologia, Sezione Roma2, Roma, Italia; Sciacca, U.; Istituto Nazionale di Geofisica e Vulcanologia, Sezione Roma1, Roma, Italia; Zirizzotti, A.; Istituto Nazionale di Geofisica e Vulcanologia, Sezione Roma2, Roma, Italia; Zuccheretti, E.; Istituto Nazionale di Geofisica e Vulcanologia, Sezione Roma2, Roma, Italia Abstract: A Radio Echo Sounding (RES) system is an active remote-sensing instrument that uses electromagnetic wave penetration into the ice to obtain information on the depth of the bedrock and on the ice thickness and its inhomogeneities, i.e. internal layering of glaciers and subglacial lake exploration. In 1995 the INGV developed its own airborne radio echo sounding system, which is continuously being upgraded. During the 1995, 1997, 1999, 2001 and 2003 Italian Antarctic Expeditions, the RES system was used to investigate different Antarctic regions. During 2007-2008 campaign, new RES systems will be used. In the following the main characteristics of the systems will be briefly described. 2008-06-30T22:00:00Z http://hdl.handle.net/2122/4007 Title: RES Investigation of the Aurora Basin Area (East Antarctica) Authors: Cafarella, L.; Istituto Nazionale di Geofisica e Vulcanologia, Sezione Roma2, Roma, Italia; Urbini, S.; Istituto Nazionale di Geofisica e Vulcanologia, Sezione Roma2, Roma, Italia; Bianchi, C.; Istituto Nazionale di Geofisica e Vulcanologia, Sezione Roma2, Roma, Italia; Zirizzotti, A.; Istituto Nazionale di Geofisica e Vulcanologia, Sezione Roma2, Roma, Italia; Tabacco, I. E.; Dipartimento Scienze della Terra, Sez. Geofisica, Milano - Italy; Forieri, A.; Dipartimento Scienze della Terra, Sez. Geofisica, Milano - Italy Abstract: We analyse radio echo sounding (RES) data on the region between Lake Vostok and the Belgica Subglacial Highlands (East Antarctica) collected during four Italian expeditions (1995, 1999, 2001 and 2003). The survey aimed to define the morphological characteristics of the Aurora Trench and to aid the exploration of subglacial lakes. 2008-06-30T22:00:00Z http://hdl.handle.net/2122/4006 Title: Evidence for Possible New Subglacial Lakes along a Radar Transect Crossing the Belgica Highlands and the Concordia Trench Authors: Forieri, A.; Università degli Studi di Milano, Sez. Geofisica, Via Cicognara 7, 20129 Milano - Italia; Tabacco, I. E.; Università degli Studi di Milano, Sez. Geofisica, Via Cicognara 7, 20129 Milano - Italia; Cafarella, L.; Istituto Nazionale di Geofisica e Vulcanologia, Sezione Roma2, Roma, Italia; Urbini, S.; Istituto Nazionale di Geofisica e Vulcanologia, Sezione Roma2, Roma, Italia; Bianchi, C.; Istituto Nazionale di Geofisica e Vulcanologia, Sezione Roma2, Roma, Italia; Zirizzotti, A.; Istituto Nazionale di Geofisica e Vulcanologia, Sezione Roma2, Roma, Italia Abstract: Subglacial lakes are of great interest to the scientific community, and about 190 lakes have been identified in Antarctica and catalogued (Siegert et al., 2005; Cafarella et al., 2006; Popov & Masolov, 2007). We report on the possible existence of 5 new subglacial lakes in the area between the Belgica HighLands and the Concordia Trench. Analysis of radar data collected during the 2003 Antarctic field survey reveals particularly strong radar echoes coming from the subglacial interface. As radar surveys are only one of the methods used to identify subglacial lakes, the presence of these 5 new lakes must be discussed and confirmed through other geophysical investigations. 2008-06-30T22:00:00Z http://hdl.handle.net/2122/3890 Title: Glacio RADAR system and results Authors: Zirizzotti, A.; Istituto Nazionale di Geofisica e Vulcanologia, Sezione Roma2, Roma, Italia; Baskaradas, J. A.; Istituto Nazionale di Geofisica e Vulcanologia, Sezione Roma2, Roma, Italia; Bianchi, C.; Istituto Nazionale di Geofisica e Vulcanologia, Sezione Roma2, Roma, Italia; Sciacca, U.; Istituto Nazionale di Geofisica e Vulcanologia, Sezione Roma1, Roma, Italia; Tabacco, I. E.; Università di Milano/ Dipartimento scienza della terra, Via Cicognara 7 20129 Milano Italy; Zuccheretti, E.; Istituto Nazionale di Geofisica e Vulcanologia, Sezione Roma2, Roma, Italia Editors: IEEE Aerospace and Electronics Systems Society, (AESS); IEEE Aerospace and Electronics Systems Society Abstract: Since 1997 the Istituto Nazionale di Geofisica e Vulcanologia (INGV) in Italy has been involved in the development of the airborne RES system named Glacio RADAR, which is continuously upgraded. Radio Echo Sounding (RES) techniques are widely used in glaciological measurements. They are based on the use of radar systems, to obtain information concerning ice thickness of ice sheets and ice shelves, internal layering of glaciers, detection of inhomogeneities, exploration of subglacial lakes and identification of physical nature of subglacial interface. The Glacio RADAR is mounted on an aircraft and flies at an altitude around 300m above the ice surface during the survey. The first prototype operates in bistatic mode with separate transmit and receive one wire folded dipole installed beneath the aircraft wings. It works at 60 MHz with an envelope pulse width variable between 0.3 s and 1 s. The receiving window is 64 s which implies a maximum penetration depth (range) in the ice of about 5.3 km. The horizontal sampling rate is 10 traces/s at a mean aircraft speed of about 70 m/s. This would produce roughly 143 traces per kilometre (horizontal resolution of 1 trace every 7 m). The Navigation and geographical information is based on a on board GPS receiver giving longitude, latitude, altitude and time for the acquired radar trace. This radar was used in several Italian Antarctic Expeditions (1997, 1999, 2001 and 2003) and highlights of data results from these expeditions are presented here. 2008-05-25T22:00:00Z http://hdl.handle.net/2122/3787 Title: Spatial and temporal variability of surface mass balance near Talos Dome, East Antarctica Authors: Frezzotti, M.; Ente per le Nuove Tecnologie, l’Energia e l’Ambiente, Rome, Italy; Urbini, S.; Istituto Nazionale di Geofisica e Vulcanologia, Sezione Roma2, Roma, Italia; Proposito, M.; Ente per le Nuove Tecnologie, l’Energia e l’Ambiente, Rome, Italy; Scarchilli, C.; Ente per le Nuove Tecnologie, l’Energia e l’Ambiente, Rome, Italy - Dipartimento di Scienze della Terra, University of Siena, Siena, Italy; Gandolfi, S.; Dipartimento di Ingegneria delle Strutture, dei Trasporti, delle Acque, del Rilevamento, del Territorio, University of Bologna, Bologna, Italy Abstract: Predictions concerning Antarctica’s contribution to sea level change have been hampered by poor knowledge of surface mass balance. Snow accumulation is the most direct climate indicator and has important implications for paleoclimatic reconstruction from ice cores. Snow accumulation measurements (stake, core, snow radar) taken along a 500-km transect crossing Talos Dome (East Antarctica) have been used to assess accumulation signals and the representativeness of ice core records. Stake readings show that accumulation hiatuses can occur at sites with accumulation rates below 120 kg m 2 yr 1. Differences between cores and stakes can lead to statistical misidentification of annual layers determined from seasonal signals at sites with accumulation rates below 200 kg m 2 yr 1 because of nondetection of higher and lower values. Achieving ±10% accuracy in the reconstruction of snow accumulation from single cores requires high accumulation (750 kg m 2 yr 1). Low-accumulation sites are representative if cumulative rates computed over several years are used to reach the 750 kg m 2 yr 1 threshold. Temporal variability of accumulation over the last two centuries shows no significant increase in accumulation. Wind-driven processes are a fundamental component of surface mass balance. Spatial variations in accumulation are well correlated with surface slope changes along the wind direction and may exceed 200 kg m 2 yr 1 within 1 km. Wind-driven sublimation rates are less than 50 kg m 2 yr 1 in plateau areas and up to 260 kg m 2 yr 1 in slope areas and account for 20–75% of precipitation, whereas depositional features are negligible in surface mass balance. 2006-12-31T23:00:00Z