Blue ice areas and their topographical properties in the Lambert glacier, Amery Iceshelf system using Landsat ETM+, ICESat laser altimetry and ASTER GDEM data

Abstract

AbstractBlue ice extent and its geographical distribution during the three years from December 1999–January 2003 have been mapped together with rock exposure areas for the entire Lambert-Amery glacial basin at an unprecedented level of spatial detail using Landsat ETM+ images. Various geometric and shape attributes for each blue ice patch have been derived. The total area of blue ice is estimated to be 20 422 km2, accounting for 1.48% of the glacial basin. We also found that the image texture information is helpful for distinguishing different types of blue ice: rough blue ice, smooth blue ice, and level blue ice. Rough blue ice areas are mostly associated with glacial dynamics and located in relatively low elevation regions, smooth blue ice areas are often related to nunataks and mountains, steep slopes and wind blows, and level blue ice areas are formed by melt-induced lakes in the margin of the ice shelf and melt-induced ponds on the ice shelf in low elevations. The elevation and surface slope properties of different types of blue ice area are characterized through regional topographical analysis with ICESat laser altimetry data. The effect of mountain height on the blue ice extent is also examined with local topographic profile analysis based on the ASTER global digital elevation model. The wide variation of the ratio of blue ice area length to mountain height indicates that the factors controlling the formation and extent of blue ice are more complicated than we previously thought.