Monitoring Muztagh Kuksai glacier surface velocity with L-band SAR data in southwestern Xinjiang, China

This study presents the results of measuring surface velocity fields of alpine glaciers with multi-temporal ALOS/PALSAR synthetic aperture radar (SAR) data using the normalized cross-correlation technique. The main limitations of spaceborne optical data and interferometric SAR for retrieving reliable interferometric product are firstly discussed. Next, an efficient method of deriving surface velocity with spaceborne SAR system using the intensity-tracking method based on the cross-correlation optimization is expounded. This method is an invaluable alternative way of estimating the glacier surface field when the differential SAR interferometry is limited by the loss of coherence and can also overcome the drawback of the lack of available optical data in alpine glacier areas. The method was successfully applied in the region of the Muztagh Kuksai Glacier using ALOS/PALSAR L-band data with 44 days temporal separation. The glacier surface velocity fields were obtained for two different time intervals (14 January to 11 March 2009 and 1 September to 17 October 2009). The accuracy of the method was estimated from the residual value in the non-glacier area, which is often used to evaluate the performance of the approach for monitoring the glacier surface velocity. Finally the distribution maps of the surface velocity fields on the Muztagh Kuksai Glacier were retrieved with an accuracy of 0.3 m (SD 0.2 m) using L-band spaceborne SAR data. The results show that overall average velocity for 1 September to 17 October in 2009 is about 11 % faster than that for 14 January to 11 March in 2009. It is concluded that the potential of monitoring the long-term evolution of glaciers with SAR data should be emphasized.