Author(s): Unfeng Wei; Shiyin Liu; Junli Xu; Wanqin Guo
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Abstract: This paper evaluates the suitability of available data – the ASTER GDEM with the DEMs derived from 1:50000 topographic maps for glaciological application. The topographic maps, constructed from aerial photography in the 1970s, were used to create a digital elevation model with 15 m resolution; the ASTER GDEM with 30 m resolution was produced from 2000s ASTER images by the Ministry of Economy, Trade and Industry (METI) of Japan and the United States National Aeronautics and Space Administration (NASA) and released in June 2009. We converted the two DEMs to the same coordinate system (WGS-1984) and the same resolution (30 m); compared the DEM extracted for topographic maps to ASTER GDEM on a cell-by-cell basis, after removing the relative horizontal bias with the orthogonal polynomial model; correlated the vertical differences between the DEMs with topographic characteristics (elevation and slope); and then estimated the change of glaciers in Altai, China. The RMSE of the DEM derived from topographic maps with respect to the ASTER GDEM on non-glaciated area was 8.76 m, which is better than the accuracy of 20 m reported by ASTER GDEM Validation Team, and is suitable for glaciological application. Mean elevation errors greater than 10 m occur on the slopes more than 50°; and the accuracy on N-facing slope is more than on other slopes obviously. The vertical differences in study area on the elevation of 1600–1750 m are greater than on other elevations. In the period 1970–2001, the mean vertical change in the surface of glaciers in Altai is -16 m, and a total ice volume of about 5 billion m3 is lost, pointing the glacier shrinkage in the Altai Mountains in China.
Year: 2012