Investigation of glacial dynamics in Lambert Glacial basin using satellite remote sensing techniques.

摘要

The Antarctic ice sheet mass budget is a very important factor for global sea level. An understanding of the glacial dynamics of the Antarctic ice sheet are essential for mass budget estimation. Utilizing a surface velocity field derived from Radarsat three-pass SAR interferometry, this study has investigated the strain rate, grounding line, balance velocity, and the mass balance of the entire Lambert Glacier - Amery Ice Shelf system, East Antarctica.; The surface velocity increases abruptly from 350 m/year to 800 m/year at the main grounding line. It decreases as the main ice stream is floating, and increases to 1200 to 1500 m/year in the ice shelf front. The strain rate distribution defines the shear margins of ice flows. The major ice streams and their confluence area experience the most severe ice deformation. The width of the shear margin decreases as it flows downstream except for the convergent areas with tributary glaciers. The grounding line for the main ice stream and the boundary of Amery Ice Shelf and surrounding tributary glaciers is delineated.; The total basal melting is estimated to be 87.82 +/- 3.78 Gt/year for the entire Amery Ice Shelf. Compared with the ice flux (16.35 +/- 3.11 Gt/year) at the ice shelf front, basal melting is apparently the dominant discharging process of the system. The melting rate for the Amery Ice Shelf decreases rapidly from the grounding zone (21.64 +/- 2.17 m/year) to the ice shelf front (-0.95 +/- 0.14 m/year).; The Lambert Glacial Basin contributes the total ice mass of 95.64 +/- 2.89 Gt/year to the ocean, which is equivalent to increasing the global sea level by 0.24 mm/year. Considering 90.54 +/- 1.55 Gt/year of snow accumulation, the entire Lambert Glacier - Amery Ice Shelf system is slightly negatively imbalanced at -5.09 +/- 3.46 Gt/year. Although the entire system is estimated to have a slight negative mass balance, three sub-glacial systems have a net positive mass balance due to a relatively high snow accumulation rate or relatively slow ice motion. Considering the large mass loss in West Antarctica, it is believed that the overall mass budget in Antarctica is negative based on this research.