The morphology of the Lichen Hills in the upper section of Rennick Glacier, Victoria Land, Antarctica, is summarised as follows: (a) a top surface on the volcanic rocks with scattered erratic blocks; (b) an exhumed Kukri Peneplain, sculptured with roches moutonnees with striae and crescentic gouges on which lie moraines and patches of drift of mainly volcanic rocks; (c) a granitic bedrock eroded by glaciers into sharp peaks and cirques on top of which there is a glacial drift attributable to ancient blue-ice areas higher than those observed at present and which may be correlated with the Terra Nova drift (Late Wisconsin); (d) various Holocene ice-cored moraines that are pushed to the lee side of the nunataks arid are often banded in strips of different lithology. The bands of the Holocene moraines are related to the rock complexes that became exposed from the ice during the lowering of the surface of the glacier Analysis of the lithology and pattern of the supraglacial debris, as well as of the blue-ice areas, allows us to construct a depositional model for the moraines, and to relate the glacial drift to blue-ice areas existing since the Last Glacial Maximum (LGM).The proposed model shows the different stages of recession of upper Rennick Glacier that are also valid for similar situations observed in northern Victoria Land. A surface lowering of upper Rennick Glacier of several hundred metres shows that significant changes have occurred at the Pacific edge of the East Antarctic ice sheet since the LGM.

Since 1994 the Alfred Wegener Institute (AWI) has operated an airborne radio-echo sounding system for remote-sensing studies of the polar ice caps in Antarctica and in Greenland. It is used to map ice thicknesses and internal layernigs of glaciers, ice sheets and ice shelves, and is capable of penetrating ice thicknesses of up to 4 km. The system was designed and built by AWI in cooperation with Aerodata Flugmeßtechnik GmbH, Technische Umversitat Hamburg-Harburg and the Deutsches Zentrum fur Luft- und Raumfahrt e.V. The system uses state-of-the-art techniques, and results in high vertical (5 m) as well as along-track (3.25 m) resolution. The radar signal is a 150 MHz burst with a duration of 60 or 600 ns. The peak power is 1.6 kW, and the system sensitivity is 190 dB. The short backfire principle has been adopted and optimized for antennae used on Polar2, a Dormer 228-100 aircraft, resulting in an antenna gain of 14 dB each. Digital data recording allows further processing. The quality of the recorded data can be monitored on screen and as online analogue plots during the flight.

During the austral summer 1996–97 an extensive field program with geophysical and geodetic observations was carried out in the vicinity of the grounding line of Ekstromisen, Dronning Maud Land, Antarctica. The main emphasis of the joint program was placed on continuous observations of the horizontal as well as the vertical component of the ice displacement across the grounding zone. Data-processing methods for the in parts discontinuous time series and the vertical displacements in the area of the grounding zone are described, and first results presented, with the focus on the influence of the ocean tides on grounded ice. Tidal-induced deflections with amplitudes of up to 0.15 m were recorded at a station on grounded ice 1 km from the grounding line.

As an ice-sounding radar receiver and transmitter are moved together across the snow surface, the returning echoes change rapidly, forming the "spatial fading pattern". Because the fading pattern is determinedly the details of the ice-bed interface" and remains fixed in position relative to that interface while the ice moves, repeated measurements of the fading pattern can reveal the relative displacement between the snow surface and targets near the bed of the ice and/or in the ice. Six high-density grids, comprising flag lines approximately along and normal to the direction of ice flow on Ice Stream B2, West Antarctica, were repeatedly profiled with a digital 50 MHz radar system by triggering a burst of 128 pulses from the radar transmitter every 0.7 m. A highly directional microwave motion sensor and a manual event button provided registration marks along the lines. The original recorded amplitudes were resampled at a constant spatial interval by interpolation between adjacent traces to make possible an analytical comparison of fading patterns. Fading patterns recorded on different days were compared by cross-correlation analysis to estimate the horizontal displacement. Then near-surface crevasses, which locally blocked the transmitted energy, were used to correct for flag-positiomng errors. The results from the three largest grids are significantly different: differential motions between the surface and the bed range from 1 to -0.5 ma−1. We suspect that the differences are related to the complex systems of strains within the ice stream reported by Hulbe and Whillans (1997).

Data from the Filchner V Campaign were used to investigate the mass-balance conditions in the southeastern Ronne Ice Shelf (RIS), Antarctica. Radio-echo sounding and seismic measurements over this area show a maximum ice thickness of >2000 m close to the grounding line of Foundation Ice Stream. The measurements also revealed that the position of this grounding line is 40 km further south than previously thought. New mass-flux calculations result in an estimate of 51 km3 a−1 for the ice-stream transport from the ice sheet into the eastern ice shelf. The Mollereisstrom (MES), west of Foundation Ice Stream, shows a maximum ice thickness of 1100-1200 m in the grounding-line area and a mass flux of 23 km3 a−1.

Assuming steady-state conditions, mass-balance calculations based on the new data result in a mean melt rate of about 1 ma−1 at the ice-shelf base for the entire southeastern part of the RIS. The melt rate in the grounding-line area of Foundation Ice Stream exceeds 9 m a−1. In contrast, other ice streams draining into the Filchner-Ronne Ice Shelf show maximum melt rates from 1-2 ma-1. (MES) to 4 ma−1 (Rutford Ice Stream). Our calculations indicate that nearly all of the ice deposited in the drainage area of the eastern RIS on the ice sheet does not reach the ice-shelf front as original meteoric ice, but is melted at the ice-shelf base.

A variety of data are used to investigate Larsen B, which is at present the northernmost section of the Larsen Ice Shelf, Antarctic Peninsula. Recently declassified U.S. Argon satellite photographs from 1963 Kosmos photographs from 1975, Landsat images from 1986,1988 and 1990, ERS-1/2 synthetic aperture radar images from 1992-97, Radarsat from 1998 and field surveys are used to analyze the areal extent, surface characteristics and dynamic behaviour of this ice-shelf section over more than three decades. Visible and radar imagery together with field observations are used synergistically to describe the ice-shelf morphology, including meltwater features and rifts. In contrast to the retreat of the ice-shelf sections in the north, Larsen B advanced steadily from 1963 to early 1995, when the area decreased significantly due to a major calving event. Analysis of different satellite images indicates that melting is proceeding further south in accordance with the regional warming trend. In addition? fracturing processes and rapid development of new rifts are observed, associated with recent acceleration of ice motion close to the front. All observations predict major calving events for this ice-shelf section in the near future.

The motion field of the northern Larsen Ice Shelf, Antarctic Peninsula, was analyzed, based on Landsat data from 1986 to 1989, Earth Resources Satellite (ERS) synthetic aperture radar (SAR) data from 1992 to 1997, and comparative field measurements along three transects. During this period the northern sections of the ice shelf showed steady retreat, which culminated in the disintegration of the two ice-shelf sections north of Seal Nunataks in January 1995. Velocities of these two sections were derived by cross-correlation, using SAR images of 1 year time intervals and Landsat images of 1-3 year intervals. A slight increase of velocity was observed as crevasses and rifts opened before the final disintegration. In addition, an interferometric motion analysis was carried out for the ice shelf around and south of Seal Nunataks, based on an image pair from the ERS-1/2 Tandem Mission in 1995. This analysis reveals a complex pattern of tidal flexure in the grounding zones, as well as rifting and shear zones on the ice shelf. In addition, the motion of the main input glaciers was derived.

Since the austral summer of 1994-95 the Alfred Wegener Institute has carried out airborne radio-echo sounding (RES) measurements in Antarctica with its newly designed RES system. Since 1995-96 an ongoing pre-site survey for an ice-coring drill site in Dronning Maud Land has been carried out as part of the European Project for Ice Goring in Antarctica. The survey covers an area of 948 000 km2, with >49 500 km of airborne RES obtained from >200 hours of flight operation flown during the period 1994-97. In this paper, first results of the airborne RES survey are graphically summarized as newly derived maps of the ice thickness and subglacial topography, as well as a three-dimensional view of surface and subglacial bed and outcrop topography, revealing a total ice volume of 1.48 x 106 km3.

High-resolution numerical model experiments were carried out along two flowlines in Dronning Maud Land, Antarctica, one flowline passing through the central part of a coastal mountain range and the other along a major continental ice stream (Shirase Glacier). Results showed that ice-sheet behaviour in response to the climatic signal differs locally. Response patterns are different for the inland ice sheet, for the coastal ice sheet and around marginal (subglacial) mountains. Modelled response time series were analyzed by lag-correlation, range and fractal analysis. Local differentiation in ice-sheet response is primarily related to the sensitive interplay between surface accumulation patterns, thermomechanical properties of the ice sheet and bedrock roughness.

To study the relationship between surface topography and satellite laser altimetry waveform, a numerical model that simulates an ideal satellite laser altimeter has been developed. It has a Gaussian beam pattern and a Gaussian pulse shape. Different three-dimensional surface topographies have been used in the simulation to generate waveforms. Using a non-linear least-squares method, the generated waveforms were fitted to theoretical models to calculate surface roughness and surface slope. The outputs from the models were then compared with the values calculated from the given assumed surfaces. There is no way to distinguish between a horizontal, randomly rough surface and a smoothly sloping surface from waveform fitting alone. However, if either the surface roughness or the surface slope can be acquired independently, the other one can be determined through waveform fitting.

The RADARSAT-1 Antarctic Mapping Project (RAMP) is a partnership between the Canadian Space Agency and the US. National Aeronautics and Space Administration. The goal of the project is to create the first complete high-resolution radar mosaic of all of Antarctica for studies of Antarctic glaciology, geology coastal processes and climate. The major participants in RAMP are the Ohio State University the Alaska SAR Facility, the Jet Propulsion Laboratory, Pasadena, GA, and Vexcel Corporation. Phase one of the project was the Antarctic Imaging Gampaign-1 (AIG) which occurred during the period 9 September-20 October 1997. The AIG relied on the abilities of the Canadian RADARSAT-1 to rotate in orbit and to image with a variety of look angles to acquire imagery from the Antarctic coast to the pole. Its primary goal was the acquisition of image data. The nearly flawless execution of the mission also enabled additional collections of exact repeat orbit data. These data, covering a large part of the interior Antarctic, are potentially suitable for interferometric analysis of surface velocity. This paper describes the AIG and the various datasets obtained! It also reviews early scientific findings on the large-scale characteristics of the ice sheet including ice divides and ice streams. The overall conclusion is that these data, which constitute complete high-resolution microwave coverage, represent a new view of the Antarctic, revealing in considerable detail the glaciology, coastal processes and geology of the Southern Continent.