HR: 0800h
AN: P31C-0211    [Abstracts]
TI: Analysis of the RANETA Imaging GPR data collected on the Antarctic Continent and Comparison with Simulated Data
AU: Ciarletti, V
EM: ciarletti@cetp.ipsl.fr
AF: CETP/IPSL, 10 12 avenue de l'Europe, Velizy, 78140 France
AU: Berthelier, J
EM: berthelier@cetp.ipsl.fr
AF: CETP/IPSL, 4 avenue Neptune, Saint Maur des Foss‚, 94107 France
AU: * Le Gall, A
EM: legall@cetp.ipsl.fr
AF: CETP/IPSL, 4 avenue Neptune, Saint Maur des Foss‚, 94107 France
AU: Dolon, F
EM: dolon@cetp.ipsl.fr
AF: CETP/IPSL, 4 avenue Neptune, Saint Maur des Foss‚, 94107 France
AU: Ney, R
EM: ney@cetp.ipsl.fr
AF: CETP/IPSL, 4 avenue Neptune, Saint Maur des Foss‚, 94107 France
AU: Reineix, A
EM: reineix@unilim.fr
AF: IRCOM, universit‚ de Limoges, Limoges, 87060 France
AB: The RANETA GPR is a pulsed HF ground penetrating radar (GPR). It was initially designed to probe the deep Martian subsurface at depths of one kilometre or more in order to search for liquid water reservoirs. In contrast with classical GPRs, this GPR is operated from the surface at a fixed position. Hence, the 2 horizontal components of the wave electric field and the 3 components of the wave magnetic field are combined to provide the propagation vector of each returning echo. In such a way, not only the distance but also the direction of the reflectors can be retrieved. In addition, the perfect stability of the environment allows to perform a very large number of coherent integrations which provide a significant signal to noise ratio even for echoes returning from deep interfaces The RANETA GPR prototype was operated at different locations on the ice of the Antarctic continent in Terre Adelie. The collected data at 2-3 and 4 MHz clearly show echoes due to the reflection of the transmitted electromagnetic waves on the bed rock at distances ranging from 300 to about 1100 meters. In most situations, the observed multiple echoes indicate that reflection occurred at different spots of the bedrock. Complementary antenna impedance measurements that bring useful information on the geoelectrical properties of subsurface have also been performed. Accurate electromagnetic simulations (using a three dimensional Finite Difference in Time Domain code) have been used to make a quantitative analysis of the available experimental data. The precise design of the electric 35 meters loaded dipole antennas, the radar structure as well as the subsurface properties have been considered to model precisely the transmitted and received waves and to make data interpretation possible. The obtained result is a simplified yet realistic mapping of the bed rock topography. As the true topography of the ice-bed rock interface is unknown, comparison between the experimental data and the results of numerical simulations taking into account the proposed subsurface structure will be shown.
DE: 5464 Remote sensing
DE: 5470 Surface materials and properties
DE: 5494 Instruments and techniques
DE: 6964 Radio wave propagation
DE: 6994 Instruments and techniques (1241)
SC: Planetary Sciences [P]
MN: Fall Meeting 2005