Abstract
We use 124 scenes of TerraSAR–X data that were acquired in 2009 and 2010 to analyse the spatial and temporal variability in surface kinematics of the debris-covered Inylchek Glacier, located in the Tien Shan mountain range in Central Asia. By applying the feature tracking method to the intensity information of the radar data and combining the results from the ascending and descending orbits, we derive the surface velocity field of the glaciated area. Analysing the seasonal variations over the upper part of the Southern Inylchek branch, we find a temperature-related increase in velocity from 25 cm/d up to 50 cm/d between spring and summer, with the peak occurring in June. Another prominent velocity peak is observable one month later in the lower part of the Southern Inylchek branch. This area shows generally little motion, with values of approximately 5–10 cm/d over the year, but yields surface kinematics of up to 25 cm/d during the peak period. Comparisons of the dates of annual glacial lake outburst floods (GLOFs) of the proglacial Lake Merzbacher suggest that this lower part is directly influenced by the drainage, leading to the observed mini-surge, which has over twice the normal displacement rate. With regard to the GLOF and the related response of Inylchek Glacier, we conclude that X–band radar systems such as TerraSAR–X have a high potential for detecting and characterising small-scale glacial surface kinematic variations and should be considered for future inter-annual glacial monitoring tasks.
Highlights
The Tien Shan mountain range, located in Central Asia, contains a large number of high-mountain glacial sites
This paper is organised as follows: First, we provide a detailed description of the setting and special conditions of the Inylchek Glacier
Afterwards, we present in detail the spatial and temporal variability of the surface velocity gained from the displacement maps and we discuss the seasonal kinematics from 2009 and 2010 with respect to the air temperature and the yearly glacial lake outburst floods (GLOFs) events
Summary
The Tien Shan mountain range, located in Central Asia, contains a large number of high-mountain glacial sites. The ice has a volume of around 1000 km and is distributed over an area of approximately. Many studies have been conducted to investigate the long-term changes of the Tien Shan glaciers with remote sensing data from e.g., Shuttle Radar Topography Mission (SRTM) and Advanced Spaceborne. An extensive summary of recent investigations regarding the retreat of Tien Shan glaciers is given by [6]. Those studies consistently show a current decrease of the glaciated area, which has notably accelerated since 1970. Glaciers situated in the Northern Tien Shan range are more affected than those of Central Tien Shan. The observed ablation phenomena are related to an increase of the annual mean temperature, whereas a significant trend in precipitation changes has not yet been detected [2,5]
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