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The northern Antarctic Peninsula is one of the fastest changing regions on Earth. The disintegration of the Larsen-A Ice Shelf in 1995 caused tributary glaciers to adjust by speeding up, surface lowering, and overall increased ice-mass discharge. In this study, we investigate the temporal variation of these changes at the Dinsmoor–Bombardier–Edgeworth glacier system by analyzing dense time series from various spaceborne and airborne Earth observation missions. Precollapse ice shelf conditions and subsequent adjustments through 2014 were covered. Our results show a response of the glacier system some months after the breakup, reaching maximum surface velocities at the glacier front of up to 8.8 m/d in 1999 and a subsequent decrease to ∼1.5 m/d in 2014. Using a dense time series of interferometrically derived TanDEM-X digital elevation models and photogrammetric data, an exponential function was fitted for the decrease in surface elevation. Elevation changes in areas below 1000 m a.s.l. amounted to at least 130 ± 15 m between 1995 and 2014, with change rates of ∼3.15 m/a between 2003 and 2008. Current change rates (2010–2014) are in the range of 1.7 m/a. Mass imbalances were computed with different scenarios of boundary conditions. The most plausible results amount to − 40.7 ± 3.9 Gt . The contribution to sea level rise was estimated to be 18.8 ± 1.8 Gt , corresponding to a 0.052 ± 0.005 mm sea level equivalent, for the period 1995–2014. Our analysis and scenario considerations revealed that major uncertainties still exist due to insufficiently accurate ice-thickness information. The second largest uncertainty in the computations was the glacier surface mass balance, which is still poorly known. Our time series analysis facilitates an improved comparison with GRACE data and as input to modeling of glacio-isostatic uplift in this region. The study contributed to a better understanding of how glacier systems adjust to ice shelf disintegration.

Hielo Patagonico Sur (HPS), an icefield in Southern Patagonia, is the largest temperate ice mass in the southern hemisphere. Despite continued research efforts during the last decade many glaciological variables, especially mass balance, are still poorly known. This is partly because access to the icefield is difficult due to remoteness and persistent harsh weather conditions. Therefore, remote sensing appears to be a more suitable tool for the acquisition of data. In this work we present a remote sensing study of snow zonation on HPS using Landsat 5 Thematic Mapper data acquired on 12 March 2001. By using image processing and classification techniques, proved to be useful in other glaciated regions, we map for the first time the extent and occurrence of major snow zones on the whole HPS. We separate between two classes of ice and three classes of snow. Ice facies are classified as bare or debris (i.e. dirt) covered ice, covering 2454 km 2 and 777 km 2 respectively, or 18.4% and 5.8% of the icefield on the day of image acquisition. Snow types are classified according to spectral differences in the images, following the glacier facies concept. Two of the three snow cover types are interpreted to represent differences in snow grain size within a fairly homogeneous snow pack whereas the third one is interpreted to represent the slush zone. A first order altitudinal control on the distribution of these snow facies is evident. In addition, our results show that snow accumulation on HPS is markedly controlled by the interaction of strong west–northwest snow-bearing winds and the rough mountainous terrain. In order of decreasing altitude we find that the two snow facies and the slush facies occupy 3819 km 2 , 3292 km 2 and 2295 km 2 respectively, or 28.6%, 24.6% and 17.2% of the icefield, on the day of image acquisition. Estimates of equilibrium line altitude using our results yield values of 800–900 m above sea level for the western side and 1500–1600 m above sea level for the eastern side, with an accumulation area ratio of 0.74.

Recent unexpected changes in the Antarctic Ice Sheet, including ice sheet thinning, ice shelf collapse and changes in ice velocities, along with the recent realization that as much as one third of ice shelf mass loss is due to bottom melt, place a new urgency on understanding the processes involved in these changes. Technological advances, including very new or forthcoming satellite-based (e.g. ICESat, CryoSat) remote sensing missions, will improve our ability to make meaningful determinations of changes in Antarctic Ice Sheet mass balance.This paper is the result of a workshop held to develop a strategy for international collaboration aimed at the collection and synthesis of Antarctic Ice Sheet mass balance data, and at understanding the processes involved so that we might predict future change. Nine sets of recommendations are made, concerning the most important and sensitive measurements, temporal ranges and study areas. A final tenth recommendation calls for increased synthesis of ice sheet data and communication between the field measurement, satellite observation and modelling communities. (C) 2004 Published by Elsevier B.V.

Glaciar Mayo, covering an area of 43 km 2 , is an eastern outlet glacier of the Southern Patagonian Icefield at its narrowest part. Aerial photographs from 1970, an optical satellite image of 1986 and synthetic aperture radar (SAR) images of the SIR-C/X-SAR, acquired in 1994, were used to investigate changes of the glacier terminus and of an ice-dammed lake, and to derive the surface velocity in the ablation area. In 1970, the glacier was damming a lake, Laguna Escondida, covering 8.6 km 2 . The analysis of the 1986 image reveals a 56% decrease in the area of the lake, the size in the SAR images from 1994 is similar. The western front of Glaciar Mayo advanced slightly between 1970 and 1986 and then retreated by about the same amount until 1994, whereas the eastern front retreated during both periods. The retreat of Glaciar Mayo is in accordance with the general glacier recession observed during the last three decades for almost all glaciers of the Patagonian icefields. Striking features in the images are two major debris bands across the terminus, the first originating from rock fall before 1959, the second from rock fall between 1970 and 1986. The second band was displaced between 1986 and 1994 with an average velocity of 288 m/year (79 cm/day). For the same trajectory, a motion of 80 cm was derived for a 24 h period in October 1994 with L-Band SIR-C data by means of interferometry. The agreement of the velocities derived by the two methods indicates little seasonal and interannual variability of ice motion, as observed also on the neighbouring Glaciar Perito Moreno.