DSpace Collection: 02.02.05. Ice dynamics

Snow dunes and glazed surfaces in Antarctica: new field and remote-sensing data

Mon, 29 Oct 2001 22:58:59 GMT

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.

A New Bedrock Map of the Dome C Area

Tue, 29 Oct 2002 22:58:59 GMT

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.

Un karst sous la glace de l'Antarctide ?

Tue, 29 Oct 2002 22:58:59 GMT

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.

Evidence of 14 New Subglacial Lakes in the Dome C-Vostok Area

Tue, 29 Oct 2002 22:58:59 GMT

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.