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Bering Glacier, Alaska, USA, has a ∼20 year surge cycle, with its most recent surge reaching the terminus in 2011. To study this most recent activity a time series of ice velocity maps was produced by applying optical feature-tracking methods to Landsat-7 ETM+ imagery spanning 2001-11. The velocity maps show a yearly increase in ice surface velocity associated with the down-glacier movement of a surge front. In 2008/09 the maximum ice surface velocity was 1.5 ±0.017 km a-1 in the mid-ablation zone, which decreased to 1.2 ±0.015 km a-1 in 2009/10 in the lower ablation zone, and then increased to nearly 4.4 ± 0.03 km a-1 in summer 2011 when the surge front reached the glacier terminus. The surge front propagated down-glacier as a kinematic wave at an average rate of 4.4 ±2.0 km a-1 between September 2002 and April 2009, then accelerated to 13.9 ± 2.0 km a-1 as it entered the piedmont lobe between April 2009 and September 2010. The wave seems to have initiated near the confluence of Bering Glacier and Bagley Ice Valley as early as 2001, and the surge was triggered in 2008 further down-glacier in the mid-ablation zone after the wave passed an ice reservoir area.

Despite containing only 14% of the Greenland ice sheet by area, the southeastern sector has the highest accumulation rates, and hence receives ∼30% of the total snow accumulation. We present accumulation rates obtained during our 2010 Arctic Circle Traverse derived from three 50 m firn cores dated using geochemical analysis. We tracked continuous internal reflection horizons between the firn cores using a 400 MHz ground-penetrating radar (GPR). GPR data combined with depth-age scales from the firn cores provide accumulation rates along a 70 km transect. We followed an elevation gradient from ∼2350 to ∼1830m to understand how progressive surface melt may affect the ability to chemically date the firn cores and trace the internal layers with GPR. From the firn cores, we find a 52% (∼0.43 m w.e. a-1) increase in average snow accumulation and greater interannual variability at the lower site than the upper site. The GPR profiling reveals that accumulation rates are influenced by topographic undulations on the surface, with up to 23% variability over 7 km. These measurements confirm the presence of high accumulation rates in the southeast as predicted by the calibrated regional climate model Polar MM5.

Investigations into glacial changes, including understanding variations in the rates of glacial volume and surface-elevation changes, have increased over the past decade. This study uses historical glacier elevation data in the form of topographic maps from 1970 and a digital elevation model from the mid-1980s to calculate surface-elevation and volume changes for Ha-Iltzuk Icefield, southwest British Columbia, Canada. Results indicate that the icefield thinned at an average rate of 0.76±0.25 ma–1 during this period. A previous study of Ha-Iltzuk Icefield also using the geodetic method found a thinning rate of 1.0±0.20ma–1 between the mid-1980s and 1999, indicating a slight increase in the amount of icefield thinning. Within the ablation zone, thinning increased with decreasing elevation at a rate of 1.9±0.68 ma–1 km–1 between these two periods (1970 to mid-1980s versus mid-1980s to 1999). Analysis of meteorological data suggests that increases in both temperature and rainfall, as well as decreases in snowfall, likely contributed to the increased thinning rate.

Large variations in both snow water equivalent (SWE) and snow slope stability are known to exist in the alpine snowpack, caused by wind, topographic and microclimatic effects. This variability makes extrapolation of point measurements of snowpack properties difficult and prone to error, but these types of measurements are used to estimate SWE and stability across entire mountain ranges. Radar technology provides a promising alternative to point measurements, because large areas can be covered quickly and non-intrusively. There is great potential for obtaining information on a large spatial scale from airborne applications. Frequency-modulated continuous wave (FMCW) radar measurements were made from the ground in several different alpine snowpacks, along with manual and in situ electrical measurements. The surface and ground reflections from the radar data, combined with an average density estimate, can provide a useful estimate of SWE. In addition, the locations of internal reflections are highly correlated with both visually identified layers and measured changes in in situ dielectric properties.

Seward Glacier, on the Alaskan/Yukon border along the Gulf of Alaska, sits atop an important structural and morphological junction in the Saint Elias orogen. It is situated at the intersection between the Fairweather and Bagley strike–slip faults, and in the hanging wall of the Malaspina and Chugach–Saint Elias thrust faults. An ice surface velocity map of Seward Glacier derived from interferometric synthetic aperture (InSAR) reveals a complex flow pattern, which implies there is a previously unmapped northwest-trending supra-/subsurface ridge crossing the Seward. Analysis of additional remote-sensing images, ASTER, ERS SAR and the InSAR coherence map, confirms this observation. The presence of this ridge leads to a set of tectonic models describing the possible interaction of the underlying faults.

Daily acquisitions from satellite microwave sensors can be used to observe the spatial and temporal characteristics of the Arctic sea-ice snowmelt onset because the initial presence of liquid water in a dry snowpack causes a dramatic change in the active-and passive-microwave response. A daily sequence of backscatter coefficient images from the NASA scatterometer (NSCAT) clearly shows the spatially continuous progression of decreasing backscatter associated with snowmelt onset across the Arctic Ocean during spring 1997. A time series of the active NSCAT backscatter and a scattering index from the passive Special Sensor Microwave/Imager (SSM/I) show similar trends during the time of the melt onset. An NSCATsnowmelt-onset detection algorithm is developed using the derivative of the backscatter with respect to time to select a melt-onset date for each pixel, generating a melt map for the Arctic sea ice. Comparison between this melt map and one previously generated from an SSM/I scattering index shows the NSCAT algorithm predicts the onset occurs 1−10 days earlier than the SSM/I-based algorithm for most portions of multi-year ice.

The space-shuttle-based SIR-C/X-SAR synthetic aperture radar (SAR) imaged part of Hielo Patagónico Sur (HPS; southern Patagonia ice field, South America) for five successive days during missions in April and October 1994. A significant meteorological event occurred during each mission, including a major storm in April and a sharp temperature decrease in October. Changes in backscatter are observed for both episodes in X-SAR returns from the mid-portions of one of the two large outlet glaciers in the study area. Ground-station and satellite meteorological, and hydrological data are combined with the daily X-SAR images to interpret changes in glacier surface conditions caused by meteorological events. Effects interpreted from the April storm are (1) wind- and precipitation-influenced surface roughening of a wet snowpack, and (2) the deposition of new wet snow at lower elevation and its subsequent retreat up-glacier. An abrupt decrease in regional temperature during October is thought to reduce the snow wetness and increase grain-size. The changes in the radar-defined glacier zones due to the April precipitation event are subtle, while the October temperature drop causes significant backscatter increases. Our results suggest that trends in HPS glacier surface and near-surface conditions observable from spaceborne SARs are not significantly masked by precipitation events.

The first topographic and ice-motion maps of the northwestern flank of Hielo Patagónico Norte (HPN, northern Patagonia Icefield), in Chile, were produced using satellite synthetic-aperture interferometric radar data acquired by NASA’s Spaceborne Imaging Radar C instrument in October 1994. The topographic map has a 10 m vertical precision with a 30 m horizontal spacing, which should be sufficient to serve as a reference for monitoring future mass changes of the icefield. The ice-motion map is accurate to within 4 mm d−1 (or 1 m a−1). The radar-derived surface topography and ice velocity are used to estimate the ice discharge from the accumulation area of four outlet glaciers, and the calving flux and mass balance of Glaciar San Rafael. The results demonstrate the use of SAR interferometry for monitoring glaciological parameters on a spatial and temporal scale unattainable by any other means.