http://hdl.handle.net/2122/121 Tue, 21 May 2013 07:28:44 GMT 2013-05-21T07:28:44Z 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/2122/8440 Title: Intervento reatino "Rete WiFi" Authors: Cardinale, Vincenzo; Istituto Nazionale di Geofisica e Vulcanologia, Sezione CNT, Roma, Italia Editors: Cardinale, Vincenzo Abstract: A seguito di una sequenza sismica nell’area reatina (settembre 2010) si è deciso di installare una rete temporanea che potesse aumentare in quell’area il numero di stazioni in tempo reale. Mon, 20 Dec 2010 23:00:00 GMT http://hdl.handle.net/2122/8440 2010-12-20T23:00:00Z http://hdl.handle.net/2122/8391 Title: Calving
 event 
detection 
by
 observation 
of 
seiche 
effects 
on 
the
 Greenland 
fjords Authors: Walter, F.; Swiss
 Seismological 
Service, 
ETH 
Zürich,
 Switzerland; Laboratory
 of
 Hydraulics,
 Hydrology 
and
 Glaciology,
 ETH
 Zürich,
 Switzerland; Olivieri, M.; Istituto Nazionale di Geofisica e Vulcanologia, Sezione Bologna, Bologna, Italia; Clinton, J.; Swiss
 Seismological 
Service, 
ETH 
Zürich,
 Switzerland Abstract: With mass loss from the Greenland ice sheet accelerating and spreading to higher latitudes, the quantification of mass discharge in the form of icebergs has recently received much scientific attention. Here, we make use of very low frequency (0.001-0.01 Hz) seismic data from three permanent broadband stations installed in the summers of 2009/2010 in northwest Greenland in order to monitor local calving activity. At these frequencies, calving seismograms are dominated by a tilt signal produced by local ground flexure in response to fjord seiching generated by major iceberg calving events. A simple triggering algorithm is proposed to detect calving events from large calving fronts with potentially no user interaction. Our calving catalogue identifies spatial and temporal differences in calving activity between Jakobshavn Isbræ and glaciers in the Uummannaq district some 200 km further north. The Uummannaq glaciers show clear seasonal fluctuations in seiche-based calving detections as well as seiche amplitudes. In contrast, the detections at Jakobshavn Isbræ show little seasonal variation, which may be evidence for an ongoing transition into winter calving activity. The results offer further evidence that seismometers can provide efficient and inexpensive monitoring of calving fronts. Sat, 31 Dec 2011 23:00:00 GMT http://hdl.handle.net/2122/8391 2011-12-31T23:00:00Z http://hdl.handle.net/2122/7840 Title: Proposal of a geomorphosite for a small glacial valley on the northeastern flank of the Mount Etna volcano (Sicily) Authors: Carveni, Pietro; Università di Catania, Italia; Benfatto, Salvo; Università di Catania, Italia; Imposa, Sebastiano; Università di Catania, Italia; Mele, Giuliana; Istituto Nazionale di Geofisica e Vulcanologia, Sezione Roma1, Roma, Italia Editors: Giusti, Christian; Paris-Sorbonne Université Abstract: Mount Etna is the largest active volcano of Europe and the highest mountain (about 3,330 m a.s.l.) of peninsular and insular Italy; moreover, during the Last Glacial Maximum (LGM, 25,000 ÷ 14,000 years BP) it was some hundreds meters higher than today. Since other mountains of the Apennines were covered by glaciers during the Upper Pleistocene, several authors hypothesized that a glacial cover could have been also present on Mount Etna during the LGM, being the estimated limit of perpetual snow around 2,500 m a.s.l. at that time and latitude. We have carried out a morphological survey in a portion of the volcanic edifice where rocks older than the LGM outcrop. This portion includes Punta Lucia, on the NW slope, and Serra delle Concazze, on the NE slope. Along the upper part of the northeastern slope of Etna we have found a small valley, about 170 m long, 15 m wide and 7 m deep, characterized by a clear U-shaped section, that we interpreted to be of glacial origin. The search for moraine deposits that could be ascribed to the activity of the hypothesized glacier was unsuccessful so far and is also complicated by the presence of vegetation and recent lava and tephra deposits covering the volcano flanks. We are aware that this valley should be considered as a possible geomorphosite to guarantee its preservation and further study. Wed, 31 Dec 2008 23:00:00 GMT http://hdl.handle.net/2122/7840 2008-12-31T23:00:00Z http://hdl.handle.net/2122/7742 Title: The sensitivity of the Late Saalian (140 ka) and LGM (21 ka) Eurasian ice sheets to sea surface conditions Authors: Colleoni, F.; Centro Euro-Mediterraneo per i Cambiamenti Climatici; Liakka, J.; Department of Meteorology, Stockholm University; Krinner, G.; Laboratoire de Glaciologie et Ge´ophysique de l’Environnement, UJF, CNRS; Jakobsson, M.; Department of Geological Sciences, Stockholm University; Masina, S.; Istituto Nazionale di Geofisica e Vulcanologia, Sezione Bologna, Bologna, Italia; Peyaud, V.; Laboratoire de Glaciologie et Ge´ophysique de l’Environnement, UJF, CNRS Abstract: This work focuses on the Late Saalian (140 ka) Eurasian ice sheets’ surface mass balance (SMB) sensitivity to changes in sea surface temperatures (SST). An Atmospheric General Circulation Model (AGCM), forced with two preexisting Last Glacial Maximum (LGM, 21 ka) SST reconstructions, is used to compute climate at 140 and 21 ka (reference glaciation). Contrary to the LGM, the ablation almost stopped at 140 ka due to the climatic cooling effect from the large ice sheet topography. Late Saalian SST are simulated using an AGCM coupled with a mixed layer ocean. Compared to the LGM, these 140 ka SST show an inter-hemispheric asymmetry caused by the larger ice-albedo feedback, cooling climate. The resulting Late Saalian ice sheet SMB is smaller due to the extensive simulated sea ice reducing the precipitation. In conclusion, SST are important for the stability and growth of the Late Saalian Eurasian ice sheet. Fri, 31 Dec 2010 23:00:00 GMT http://hdl.handle.net/2122/7742 2010-12-31T23:00:00Z http://hdl.handle.net/2122/7732 Title: Refined broad-scale sub-glacial morphology of Aurora Subglacial Basin, East Antarctica derived by an ice-dynamics-based interpolation scheme Authors: Roberts, J. L.; Department of Sustainability, Environment, Water, Population and Communities, Australian Antarctic Division, Hobart, Tasmania, Australia and Antarctic Climate and Ecosystems Cooperative Research Centre, Private Bag 80, Hobart, Tasmania 7001, Australia; Warner, R. C.; Department of Sustainability, Environment, Water, Population and Communities, Australian Antarctic Division, Hobart, Tasmania, Australia and Antarctic Climate and Ecosystems Cooperative Research Centre, Private Bag 80, Hobart, Tasmania 7001, Australia; Young, D.; Institute of Geophysics, Jackson School of Geosciences, University of Texas at Austin, Austin, Texas, USA; Wright, A.; School of GeoSciences, University of Edinburgh Edinburgh, Scotland, UK; van Ommen, T. D.; Department of Sustainability, Environment, Water, Population and Communities, Australian Antarctic Division, Hobart, Tasmania, Australia and Antarctic Climate and Ecosystems Cooperative Research Centre, Private Bag 80, Hobart, Tasmania 7001, Australia; Blankenship, D. D.; Institute of Geophysics, Jackson School of Geosciences, University of Texas at Austin, Austin, Texas, USA; Siegert, M.; School of GeoSciences, University of Edinburgh Edinburgh, Scotland, UK; Young, N. W.; Department of Sustainability, Environment, Water, Population and Communities, Australian Antarctic Division, Hobart, Tasmania, Australia and Antarctic Climate and Ecosystems Cooperative Research Centre, Private Bag 80, Hobart, Tasmania 7001, Australia; Tabacco, I. E.; Geofisica, Universita di Milano, Milan, Italy; Forieri, A.; Geofisica, Universita di Milano, Milan, Italy; Passerini, A.; Istituto Nazionale di Geofisica e Vulcanologia, Sezione Roma1, Roma, Italia; Zirizzotti, A.; Istituto Nazionale di Geofisica e Vulcanologia, Sezione Roma2, Roma, Italia; Frezzotti, M.; Agenzia nazionale per le nuove tecnologie, l’energia e lo sviluppo economico sostenibile, Rome, Italy Abstract: Ice thickness data over much of East Antarctica are sparse and irregularly distributed. This poses difficulties for reconstructing the homogeneous coverage needed to properly assess underlying sub-glacial morphology and fundamental geometric constraints on sea level rise. Here we introduce a new physically-based ice thickness interpolation scheme and apply this to existing ice thickness data in the Aurora Subglacial Basin region. The skill and robustness of the new reconstruction is demonstrated by comparison with new data from the ICECAP project. The interpolated morphology shows an extensive marine-based ice sheet, with considerably more area below sea-level than shown by prior studies. It also shows deep features connecting the coastal grounding zone with the deepest regions in the interior. This has implications for ice sheet response to a warming ocean and underscores the importance of obtaining additional high resolution data in these marginal zones for modelling ice sheet evolution. Tue, 12 Jul 2011 22:00:00 GMT http://hdl.handle.net/2122/7732 2011-07-12T22:00:00Z http://hdl.handle.net/2122/7543 Title: Glacial features on the Galicica Mountains, Macedonia: preliminary report Authors: Ribolini, A.; Dipartimento di Scienze della Terra, Università di Pisa, Pisa, Italia; Isola, I.; Istituto Nazionale di Geofisica e Vulcanologia, Sezione Pisa, Pisa, Italia; Zanchetta, G.; Istituto Nazionale di Geofisica e Vulcanologia, Sezione Pisa, Pisa, Italia; Bini, M.; Dipartimento di Scienze della Terra, Università di Pisa, Pisa, Italia; Sulpizio, R.; Dipartimento di Scienze della Terra e Geoambientali, Università di Bari, Bari, Italia; Istituto per la Dinamica dei Processi Ambientali, CNR, Milano Abstract: Glacial features were described for the first time on the Galicia Mountains, a mountain range separating the lakes of Ohrid and Prespa in Macedonia. The geomorphological mapping of part of this range allowed to document the existence of frontal and lateral moraines, as well as trimlines, cirques and polished rocks. These glacial features allowed the reconstruction of the original topography of the glaciers that deposited the frontal moraines. The Equilibrium Line Altitude (ELA) of three different phases of expansion was calculated (ca. 1850 m, ca. 2000 m and 2130 m a.s.l.) through the Area-Altitude Balance Ratio (AABR) method, and correlated with the values available for the Balkan region and northern Greece. An attribution to Last Glacial Maximum (LGM) and Lateglacial (Oldest and Younger Dryas) was argued for the glacial phases of Galicica Mountains, in agreement with the ELAs of dated moraines in the region, as well as in the Apennines and Maritime Alps. Through the extrapolation of summer temperatures at the ELAs for the single glacial phases, the amount of precipitation needed to sustain the glaciers existence was calculated (3500-3700 mm of weq) using a well established polynomial regression. The attribution to the LGM of the lowermost frontal moraine points out to an older age for the till found well below the examined area, near the Prespa Lake shore. This indicates that a more extended glaciation phase occurred during the Middle Pleistocene. Fri, 31 Dec 2010 23:00:00 GMT http://hdl.handle.net/2122/7543 2010-12-31T23:00:00Z http://hdl.handle.net/2122/7351 Title: Insights on the kinematics of deep-seated gravitational slope deformations along the 1915 Avezzano earthquake fault (Central Italy), from time-series DInSAR Authors: Moro, M.; Istituto Nazionale di Geofisica e Vulcanologia, Sezione CNT, Roma, Italia; Saroli, M.; Dipartimento di Meccanica, Strutture, Ambiente e Territorio, University of Cassino, Cassino, Italy; Tolomei, C.; Istituto Nazionale di Geofisica e Vulcanologia, Sezione CNT, Roma, Italia; Salvi, S.; Istituto Nazionale di Geofisica e Vulcanologia, Sezione CNT, Roma, Italia Abstract: Among the causes of deep-seated gravitational slope deformations (DGSD), the most important is relief energy, which is closely related to the intensity of the active tectonic deformations, either at the regional scale or at the scale of a single active fault. We analyzed some examples of DGSD from the Eastern border of the Fucino basin, in the Central Apennines, where extensional tectonics has been active since the late Pliocene. Photogeological and field geomorphological analysis was performed to identify landforms typically associated with DGSD, such as counterslope scarps, double crests, trenches, and bulging slopes. These features are located on a mountain range at less than 1 km from the causative fault of the 1915 Avezzano earthquake. We used the SBAS Differential SAR Interferometry technique to measure the slow movements of the surface, and calculated differential vertical and horizontal ground velocities of 2–4 mm yr−1 during the period spanning from 1992 to 2001. The quantitative information on the kinematics of the deformation provided some inferences on the different processes responsible for the evolution of the observed DGSD. The displacement time series shows non-linear deformation trends at some locations, possibly correlated with a strong meteorological event. We speculate that DGSD in this area are normally subject to slow deformation, and that sudden slip along sliding surfaces (observed in excavations) may sporadically be triggered off by extreme meteorological or seismic events. Evidence of catastrophic collapse of previous DGSD along the same mountain slope reinforce this hypothesis. Wed, 31 Dec 2008 23:00:00 GMT http://hdl.handle.net/2122/7351 2008-12-31T23:00:00Z