Glacio RADAR system and results

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 J,lS and 1 J,ls. The receiving window is 64 J,lS which implies a maximum penetration depth (range) in the ice of about 5.3 Ion. The horizontal sampling rate is 10 traces/s at a mean aircraft speed of about 70 mls. 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

Airborne Radio Echo Sounding (RES) measures on Alpine Glaciers to evaluate ice thickness and bedrock geometry: preliminary results from pilot tests performed in the Ortles Cevedale Group (Italian Alps).

“…Based on our past experience in airborne RES measurements [Tabacco I.E. et al, 1999 et al, Zirizzotti A. et al, 2008, we develop a 24 V.d.c. system operating at 40 MHz (4 kW maximum peak power) with an envelope pulse width variable between 25 ns (1 cycle) and 500 ns (20 cycles).…”

Electromagnetic ice absorption rate at Dome C, Antarctica

“…Lakes have been grouped in four different zones in the Concordia area to analyze different ice properties in different zones. The analyzed radar measurements were collected during different Antarctic campaigns using several different RES systems, with different transmitted peak powers (2–4 kW), and different pulse lengths (100 ns to 1 µs) at the same carrier frequency of 60 MHz (Zirizzotti and others, 2008).…”