William Krabill

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Recent aircraft and satellite laser altimeter surveys of the Amundsen Sea sector of West Antarctica show that local glaciers are discharging about 250 cubic kilometers of ice per year to the ocean, almost 60% more than is accumulated within their catchment basins. This discharge is sufficient to raise sea level by more than 0.2 millimeters per year. Glacier(More)
[1] Interferometric synthetic-aperture radar data collected by ERS-1/2 and Radarsat-1 satellites show that Antarctic Peninsula glaciers sped up significantly following the collapse of Larsen B ice shelf in 2002. Hektoria, Green and Evans glaciers accelerated eightfold between 2000 and 2003 and decelerated moderately in 2003. Jorum and Crane glaciers(More)
6. Accumulation estimates from recent cores were provided by R. Bales, pending completion of a paper updating the accumulation map for Greenland. 7. C. Davis, personal communication. 8. Values of T north of latitude 70°N shown in Fig. 3 are about 4 cm/year lower than our earlier estimates (2), reflecting improvement in estimates of snow-accumulation rates(More)
[1] Satellite radar interferometry data from 1995 to 2004, and airborne ice thickness data from 2002, reveal that the glaciers flowing into former Wordie Ice Shelf, West Antarctic Peninsula, discharge 6.8 ± 0.3 km 3 /yr of ice, which is 84 ± 30 percent larger than a snow accumulation of 3.7 ± 0.8 km 3 /yr over a 6,300 km 2 drainage basin. Airborne and(More)
Radiometer sea ice validation campaign. The comparison of the elevation measurements shows that they agree quite well with correlations of around 0.9 for individual shots and a bias of less than 2 cm. The differences are found to decrease quite rapidly when applying running means. The comparison of the roughness measurements show that there are significant(More)
morphological changes that reflect an earlier automatic response on the part of the plants to the selective pressures of seedbed and harvesting (the adaptive syndrome of domestication) (1, 2, 17). The intact Cucur-bita seeds from the Archaic period occupations of the cave provide evidence, in terms of size increase, that such an adaptive response to seedbed(More)
a r t i c l e i n f o Keywords: Satellite altimetry Radar altimeter Laser altimetry Sea ice thickness Snow depth Sea ice thickness is a crucial, but very undersampled cryospheric parameter of fundamental importance for climate modeling. Advances in satellite altimetry have enabled the measurement of sea ice freeboard using satellite microwave altimeters.(More)
High resolution airborne laser altimetry is used to determine the small-scale surface relief in central Greenland and estimate the contribution from spatial noise to stratigraphic records. The standard deviation of the surface roughness is 1.6 cm water equivalent, corresponding to a standard deviation of annual layer thickness of 2.3 cm we. This estimate(More)
polynya were used to intercalibrate the ATM and D2P altimeters before estimating an altimeter snow depth. Results show that the mean difference between the PSR and altimeter snow depths is −2.4 cm (PSR minus altimeter) with a standard deviation of 7.7 cm. The RMS difference is 8.0 cm. The overall correlation between the two snow depth data sets is 0.59.