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  • 1
    Publication Date: 2017-04-04
    Description: 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.
    Description: Finmeccanica Selex - Sistemi Integrati, Italy
    Description: Published
    Description: Sheraton Golf Parco dè Medici, Roma
    Description: 3.8. Geofisica per l'ambiente
    Description: open
    Keywords: VHF Radar ; RES-system ; 02. Cryosphere::02.02. Glaciers::02.02.99. General or miscellaneous ; 02. Cryosphere::02.02. Glaciers::02.02.10. Instruments and techniques
    Repository Name: Istituto Nazionale di Geofisica e Vulcanologia (INGV)
    Type: Conference paper
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  • 2
    Publication Date: 2017-04-04
    Description: 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.
    Description: Published
    Description: 69-73
    Description: 3.8. Geofisica per l'ambiente
    Description: JCR Journal
    Description: reserved
    Keywords: radio echo sounding (RES) ; Antarctica ; subglacial lakes ; 02. Cryosphere::02.02. Glaciers::02.02.99. General or miscellaneous
    Repository Name: Istituto Nazionale di Geofisica e Vulcanologia (INGV)
    Type: article
    Location Call Number Limitation Availability
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  • 3
    Publication Date: 2017-04-04
    Description: 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.
    Description: Published
    Description: 47-51
    Description: 3.8. Geofisica per l'ambiente
    Description: JCR Journal
    Description: reserved
    Keywords: glaciers ; radio-echo-sounding ; radio propagation in the ice ; 02. Cryosphere::02.02. Glaciers::02.02.99. General or miscellaneous ; 02. Cryosphere::02.02. Glaciers::02.02.07. Ocean/ice interaction ; 02. Cryosphere::02.02. Glaciers::02.02.10. Instruments and techniques
    Repository Name: Istituto Nazionale di Geofisica e Vulcanologia (INGV)
    Type: article
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  • 4
    Publication Date: 2017-04-04
    Description: Precise topography from European Remote-sensing Satellite radar altimetry and high density of airborne radio-echo sounding in the area surrounding Dome C, Antarctica, show a link between surface features and subglacial lakes. In this paper, we extend the study to fine structures by computing a curvature-based coefficient (cy) related to surface undulations. These coefficient variations reveal many surface undulations, and some elongated features of this parameter seem to link known subglacial lakes. A population of high values of this coefficient, assumed to correspond to transitions between sliding and non-sliding flow regime, strengthen the appearance of a network which would link most of the lakes in the area. The existence of such a network impacts on ice-flow dynamics and on subglacial-lake studies.
    Description: Published
    Description: 252-256
    Description: 3.8. Geofisica per l'ambiente
    Description: JCR Journal
    Description: reserved
    Keywords: Ice sheet ; Subglagial lakes ; 02. Cryosphere::02.02. Glaciers::02.02.03. Geomorphology ; 02. Cryosphere::02.02. Glaciers::02.02.04. Ice ; 02. Cryosphere::02.02. Glaciers::02.02.05. Ice dynamics
    Repository Name: Istituto Nazionale di Geofisica e Vulcanologia (INGV)
    Type: article
    Location Call Number Limitation Availability
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  • 5
    Publication Date: 2017-04-04
    Description: Improved knowledge of geometrical boundary conditions, such as bedrock geometry and surface topography, can contribute significantly to glaciological studies including ice-sheet-flow modelling. Precise thickness and altimetric data allow an estimation of ice-flow direction, the balance velocity and the basal shear stress. These parameters are calculated along a 1160 km profile in East Antarctica using a relationship between shear stress, basal temperature, the Glen flow exponent and a parameter related to strain rate. Strong variations of the flow-law parameters and basal conditions are found to play a major role in the ice-flow pattern. Sliding, anisotropy and longitudinal stress strongly perturb the validity of the law, but their signature can be identified.
    Description: Published
    Description: 102-106
    Description: 3.8. Geofisica per l'ambiente
    Description: JCR Journal
    Description: reserved
    Keywords: Ice sheet ; Mass balance ; Bedrock-topography ; 02. Cryosphere::02.02. Glaciers::02.02.03. Geomorphology ; 02. Cryosphere::02.02. Glaciers::02.02.04. Ice ; 02. Cryosphere::02.02. Glaciers::02.02.05. Ice dynamics
    Repository Name: Istituto Nazionale di Geofisica e Vulcanologia (INGV)
    Type: article
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  • 6
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    International Glaciological Society
    Publication Date: 2017-04-04
    Description: The power strength of the radio-echo signal coming from reflecting sub-ice surfaces is used to determine the nature of the reflecting surface, i.e. rock, water or sea water. Electromagnetic analysis shows that the amplitude variations detected by radio-echo sounding are mainly due to the nature of the interface as well as the concave or convex shape of the reflectors. In this paper, some relevant profiles showing the power variations due to the different nature of the interface and the shape of the reflectors are presented. These results are important both for surface shape determination and for subglacial lake detection.
    Description: Published
    Description: 9-12
    Description: 3.8. Geofisica per l'ambiente
    Description: JCR Journal
    Description: reserved
    Keywords: Bedrock-topography ; Ice sheet ; 02. Cryosphere::02.02. Glaciers::02.02.03. Geomorphology ; 02. Cryosphere::02.02. Glaciers::02.02.04. Ice ; 02. Cryosphere::02.02. Glaciers::02.02.05. Ice dynamics
    Repository Name: Istituto Nazionale di Geofisica e Vulcanologia (INGV)
    Type: article
    Location Call Number Limitation Availability
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  • 7
    Publication Date: 2017-04-04
    Description: Radio echo sounding (RES) systems for ice thickness measurements are practically the only suitable equipment for large-scale radar flight surveys in polar regions. The length of the radio wave carrier does not allow the employment of sophisticated antennas, so folded dipoles are used, arranged beneath the wings. As a consequence, the transmitted radio wave beam illuminates a relatively large area, making the power of the echo signal related in a significant way to the shape of the reflecting surfaces. An electromagnetic analysis shows that the amplitude variations detected by the system, under certain conditions, are mainly due to focusing or defocusing effects determined by the shape of the reflectors.
    Description: Published
    Description: 3049-3058
    Description: 1.8. Osservazioni di geofisica ambientale
    Description: JCR Journal
    Description: reserved
    Keywords: radar ; ice tongues ; airborne instrument ; 01. Atmosphere::01.01. Atmosphere::01.01.08. Instruments and techniques ; 02. Cryosphere::02.02. Glaciers::02.02.04. Ice ; 02. Cryosphere::02.02. Glaciers::02.02.06. Mass balance ; 02. Cryosphere::02.02. Glaciers::02.02.10. Instruments and techniques ; 02. Cryosphere::02.04. Sea ice::02.04.04. Instruments and techniques
    Repository Name: Istituto Nazionale di Geofisica e Vulcanologia (INGV)
    Type: article
    Location Call Number Limitation Availability
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  • 8
    Publication Date: 2017-04-04
    Description: The Frontier Mountain blue ice field is an important Antarctic meteorite trap which has yielded 472 meteorite specimens since its discovery in 1984. Remote sensing analyses and field campaigns from 1993 to 1999 have furnished new glaciological data on ice flow, ice thickness, bedrock topography, ice ablation and surface mass transport by wind, along with detailed descriptions of the field situation at the trap. This solid set of data combined with an updated meteorite distribution map and terrestrial ages available from literature allows us to better describe the nature of the concentration mechanism. In particular, we observe that the meteorite trap forms in a blue ice field (1) located upstream of an absolute and a shallow sub-ice barriers; (2) characterized by compressive ice flow with horizontal velocities decreasing from 100 to 〈10 cm/year on approaching the obstacle; (3) undergoing mean ablation rates of 6.5 cm/year; (4) nourished by a limited snow accumulation zone extending ∼20 km upstream of the blue ice area. We also draw the following conclusions: (1) the origin of the meteorite trap can be explained according to the present-day glaciological situation; (2) the meteorite concentration develops according to the general principles of the "ice flow model"; (3) the accumulation model can be described as "stagnant ice or slow-moving ice against an absolute and submerged barriers", according to the descriptive schemes present in literature; (4) the Frontier Mountain ice field is an effective trap for meteorites weighing more than ∼200 g; for smaller masses, the combination of wind and glacial drift may remove meteorites in less than a few tens of thousands of years; (5) although the activation age of the Frontier Mountain trap is not yet constrained, we infer that one of the most important findsites may be as old as 50 ka, predating the last glacial maximum.
    Description: Published
    Description: 209-228
    Description: JCR Journal
    Description: reserved
    Keywords: Frontier Mountain ; Antarctic meteorite trap ; remote sensing ; glaciological data ; 04. Solid Earth::04.02. Exploration geophysics::04.02.04. Magnetic and electrical methods ; 04. Solid Earth::04.02. Exploration geophysics::04.02.05. Downhole, radioactivity, remote sensing, and other methods ; 04. Solid Earth::04.02. Exploration geophysics::04.02.06. Seismic methods
    Repository Name: Istituto Nazionale di Geofisica e Vulcanologia (INGV)
    Type: article
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  • 9
    Publication Date: 2017-04-04
    Description: 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.
    Description: Published
    Description: 199-201
    Description: 3.8. Geofisica per l'ambiente
    Description: N/A or not JCR
    Description: open
    Keywords: radio echo sounding (RES) ; Antarctica ; subglacial lakes ; 02. Cryosphere::02.02. Glaciers::02.02.99. General or miscellaneous
    Repository Name: Istituto Nazionale di Geofisica e Vulcanologia (INGV)
    Type: article
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  • 10
    Publication Date: 2017-04-04
    Description: 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.
    Description: Published
    Description: Milan, 25-26 June 2002 / Dipartimento di Scienze Ambiente e Territorio (DISAT), Università di Milano Bicocca, P.zza della Scienza 1, 20126 Milano
    Description: 3.8. Geofisica per l'ambiente
    Description: open
    Keywords: East Antarctica ; RES system ; EPICA ; bedrock map ; 02. Cryosphere::02.02. Glaciers::02.02.02. Cryosphere/atmosphere Interaction ; 02. Cryosphere::02.02. Glaciers::02.02.05. Ice dynamics ; 02. Cryosphere::02.02. Glaciers::02.02.06. Mass balance ; 04. Solid Earth::04.02. Exploration geophysics::04.02.99. General or miscellaneous
    Repository Name: Istituto Nazionale di Geofisica e Vulcanologia (INGV)
    Type: Conference paper
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