Title Dual-frequency altimeter signal from Envisat on the Amery Ice Shelf
Author Lacroix, P.; Legrésy, B.; Coleman, R.; Dechambre, M.; Rémy, F.
Author Affil Lacroix, P., UPS, LEGOS, Toulouse, France. Other: University of Tasmania, Australia; CETP, France
Source Remote Sensing of Environment, 109(3), p.285-294. Publisher: Elsevier, New York, NY, United States. ISSN: 0034- 4257
Publication Date Aug. 15, 2007
Notes In English. 20 refs. GeoRef Acc. No: 310018. CRREL Acc. No: 65006834
Index Terms precipitation (meteorology); glacial geology; ice shelves; analysis (mathematics); measurement; remote sensing; snow; Antarctica- -Amery Ice Shelf; Antarctica--East Antarctica; altimetry; Amery Ice Shelf; Antarctica; atmospheric precipitation; East Antarctica; elevation; fissures; glacial features; mathematical methods; roughness; satellite methods; seasonal variations; waveforms
Abstract In Antarctica, radar altimeter measurements are sensitive to dielectric and penetration properties of the sensed medium (snow) such that the spacecraft's altitude can be biased. Since 2002, relatively low frequency radar measurements over the Amery Ice Shelf, east Antarctica, have been acquired using the Envisat dual frequency altimeter at S (3.2 GHz) and Ku (13.6 GHz) bands, which penetrate a few meters into the firn. The altimeter signal is however modified in summer by the presence of snowfilled crevasses. Indeed, the specularity of the snow surfaces in summer makes the altimetric signal sensitive mostly to nadir echoes, that increases the ratio between the crevasse signal and the surrounding ice-shelf signal at nadir. Crevasses are distinguished by differences in backscattering behavior compared with the surrounding ice-shelf signal. Crevasses are characterized by a strong backscatter coefficient at Ku band and anomalies in the S band altitude estimation. These two characteristics make snowfilled crevasses detectable by the dual frequency altimeter of Envisat. (mod. journ. abst.)
URL http://hdl.handle.net/10.1016/j.rse.2007.01.007
Publication Type journal article
Record ID 91476