Deriving Ice Motion Patterns in Mountainous Regions by Integrating the Intensity-Based Pixel-Tracking and Phase-Based D-InSAR and MAI Approaches: A Case Study of the Chongce Glacier

Abstract

Abstract:As a sensitive indicator of climate change, mountain glacier dynamics are of great concern, but the ice motion pattern of an entire glacier surface cannot be accurately and efficiently generated by the use of only phase-based or intensity-based methods with synthetic aperture radar (SAR) imagery. To derive the ice movement of the whole glacier surface with a high accuracy, an integrated approach combining differential interferometric SAR (D-InSAR), multi-aperture interferometry (MAI), and a pixel-tracking (PT) method is proposed, which could fully exploit the phase and intensity information recorded by the SAR sensor. The Chongce Glacier surface flow field is estimated with the proposed integrated approach. Compared with the traditional SAR-based methods, the proposed approach can determine the ice motion over a widely varying range of ice velocities with a relatively high accuracy. Its capability is proved by the detailed ice displacement pattern with the average accuracy of 0.2 m covering the entire Chongce Glacier surface, which shows a maximum ice movement of 4.9 m over 46 days. Furthermore, it is shown that the ice is in a quiescent state in the downstream part of the glacier. Therefore, the integrated approach presented in this paper could present us with a novel way to comprehensively and accurately understand glacier dynamics by overcoming the incoherence phenomenon, and has great potential for glaciology study.

Characterizing the behaviour of surge- and non-surge-type glaciers in the Kingata Mountains, eastern Pamir, from 1999 to 2016

“…Changes in glacial motion can also be attributed to changes in precipitation and temperature over recent decades (Raper and Braithwaite, 2009). Most glaciers in the KM are relatively small compared to glaciers in nearby areas, such as the Kelayayilake Glacier (Lv et al, 2016;Shangguan et al, 2016) and Muztag Glacier (Yang et al, 2013). No in situ climate data exist for this region, making it difficult to disentangle glacier response to a change in accumulation from other factors.…”

“…Due to their remoteness and harsh environment, few ground-based glaciological studies have been carried out (Thompson et al, 1995;Ono et al, 1997;Shangguan et al, 2016). Remote-sensing studies have provided most of the available data for this region, using both optical and radar imagery to evaluate the temporal changes in glacier extent and flow (Kääb, 2002;Luckman et al, 2007;Yang et al, 2013;Yasuda and Furuya, 2015). Three approaches have generally been employed to derive displacements of the glacier surface: offset tracking based on intensity using both optical and synthetic aperture radar (SAR) imagery (Copland et al, 2009;Quincey et al, 2011Quincey et al, , 2015Burgess et al, 2013), interferometric SAR (InSAR) (Goldstein et al, 1993;Kenyi and Kaufmann, 2003;Gourmelen et al, 2011), and a combination of these two methods (Yan et al, 2016).…”

Monitoring and Analyzing Mountain Glacier Surface Movement Using SAR Data and a Terrestrial Laser Scanner: A Case Study of the Himalayas North Slope Glacier Area

“…In general, pixel offsets consist of offsets caused by orbital differences, glacial motion, topography, and the ionosphere [32]. The global offset due to orbital differences can be removed by polynomial fitting, in this paper, the non-glacial area is used to estimate the overall co-registration parameter, and there is no related systematic error in the offset results [29,30]. The ionosphere has a negligible influence on X-band images in low-, and mid-latitude areas and can thus be ignored [33].…”

“…The value of CC (L,S) reflects the similarity between the template window and the search window. When the CC (L,S) is maximized, the match between the template window and the search window is completed, and the pixel offset between the two SAR images is calculated [24,[29][30][31].…”

Auther response to two reviewer comments

“…Changes in glacial motion can also be attributed to changes in precipitation and temperature over recent decades (Raper and Braithwaite, 2009). Most glaciers in the KM are relatively small compared to glaciers in nearby areas, such as the Kelayayilake Glacier Shangguan et al, 2016) and Muztag Glacier (Yang et al, 2013). No in situ climate data exist for this region, making it difficult to disentangle glacier response to a change in accumulation from other factors.…”