Results are presented from two years of field data collected along the Siple Coast region of West Antarctica. Measurements were made in the vicinities of base camps which were established in the mouths of ice streams B and C and at the upstream edge of Crary Ice Rise. The annual rate of ice deformation in Ice Stream C is very small, generally less than 10−5 yr−1. Reoccupation of an 11 year old stake network permitted ice motion (6.1 m/yr) and grounding-line retreat (41 m/yr) to be measured. Visable strand cracks were used to map the grounding line. Its location differed from the grounding-line position determined from radar soundings by Scott Polar Research Institute (SPRI) by as much as 10 km but these differences are not believed to have dynamic significance. In contrast, Ice Stream B has no obvious grounding line near the position mapped by SPRI. The surface topography exhibits elongated ridges instead of the smoother surface of Ice Stream C. Regions of Ice Stream B with a lower surface elevation move faster than higher elevation regions, presumably because the lower-elevation ice is thinner and experiences less basal friction. Surface strain rates at Ice Stream B vary on a scale similar to the topographic relief but transverse differences in downstream velocity are only 1 to 2% of the 527 ± 50 m/yr ice motion. This value is slightly higher than predictions of the balance velocity which range between 450 and 480 m/yr. Near Crary Ice Rise, surface strain rates show increasing compression of the ice as it approaches the ice rise. The upstream boundary of Crary Ice Rise has been accurately determined based on a combination of surface measurements, aerial photography and radar-sounding data.
Weitere Kapitel dieses Buchs durch Wischen aufrufen
- Ice Stream-Ice Shelf Interaction in West Antarctica
R. A. Bindschadler
D. R. MacAyeal
S. N. Stephenson
- Springer Netherlands