Abstract
We obtained accurate, detailed motion distribution of glaciers in Central Asia by applying digital elevation model (DEM) assisted pixel-tracking method to L-band synthetic aperture radar imagery. The paper firstly introduces and analyzes each component of the offset field briefly, and then describes the method used to efficiently and precisely compensate the topography-related offset caused by the large spatial baseline and rugged terrain with the help of DEM. The results indicate that the rugged topography not only forms the complex shapes of glaciers, but also affects the glacier velocity estimation, especially with large spatial baseline. The maximum velocity, 0.85 m∙d−1, was observed in the middle part on the Fedchenko Glacier, which is the world’s longest mountain glacier. The motion fluctuation on its main trunk is apparently influenced by mass flowing in from tributaries, as well as angles between tributaries and the main stream. The approach presented in this paper was proved to be highly appropriate for monitoring glacier motion and will provide valuable sensitive indicators of current and future climate change for environmental analysis.
Highlights
Glaciers, especially mountain glaciers, are usually treated as one of the most sensitive indicators of the Earth’s climate change, which has always been characterized by natural variability such as global annual air temperature and average precipitation [1,2,3,4]
This paper presents a method to efficiently provide an accurate ice velocity distribution map for several glaciers located in the eastern Pamirs of Central Asia using pixel-tracking methods assisted with external SRTM digital elevation model (DEM) version 4 data for compensating for topographical effects, based on ALOS/PALSAR images acquired on 2 January and 17 February 2007
Synthetic Aperture Radar (SAR) imagery identified in this study is demonstrated to be a suitable approach for estimating glacier surface velocities, especially in cloud- and snow-covered glaciated mountainous areas where visible optical imagery is problematic
Summary
Especially mountain glaciers, are usually treated as one of the most sensitive indicators of the Earth’s climate change, which has always been characterized by natural variability such as global annual air temperature and average precipitation [1,2,3,4]. The former shows significant increase during the last century [5,6]. Ice melting in response to global warming in glaciated areas could further accelerate glacier flow and potentially lead to significant loss of glacier mass, which would affect river runoff, cause glacial retreat or bring about supraglacial lake outburst floods [7,9].
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