Spatial-Temporal Characteristics of Glacier Velocity in the Central Karakoram Revealed with 1999–2003 Landsat-7 ETM+ Pan Images

Abstract

Abstract:The situation of stable and slightly advancing glaciers in the Karakoram is called the "Karakoram anomaly". Glacier surface velocity is one of the key parameters of glacier dynamics and mass balance, however, the response of glacier motion to this regional anomaly is not fully understood. Here, we characterize the spatial-temporal variations in glacier velocity over the Central Karakoram from 1999-2003. The inter-annual glacier velocity fields were retrieved using a cross-correlation-based algorithm applied to four Landsat-7 Enhanced Thematic Mapper Plus (ETM+) panchromatic image pairs. We find that most of the glaciers on the southern slope flowed faster than those on the northern slope, which might be attributed to the differences in glacier sizes. Furthermore, ice motion observations over four years reveal that most of the glaciers were quasi-stable or experienced small fluctuations of flow velocity during our study period. We identify a new surging event for the South Skamri Glacier in the study period by investigating the glacier frontal changes and the longer-term time series of surface velocities between 1996 and 2006. From the transverse velocity profiles of seven typical glaciers, we infer that basal sliding is the predominant motion mechanism of the middle and upper glaciers, whereas internal deformation dominates closest to the glacier terminus.

Surface Velocity Dynamics of Samudra Tapu Glacier, India From 2013 to 2017 Using Landsat-8 Data

“…Surface velocity is estimated only in ablation area of the glaciers because more trackable features and good image contrast is available in this zone as compared to accumulation zone. This also increases the accuracy of velocity estimation (Sun et al, 2017). Mean annual surface velocity along the centre flow line during 2013 to 2017 are compiled in Table 3.…”

“…Optical and microwave remote sensing are generally used in surface velocity estimation. Optical remote sensing data are now-a-days commonly used for surface velocity estimation by researchers using feature tracking method due to availability of data from large number of optical sensor, from low resolution to high resolution (Bhushan et al, 2018;Paul et al, 2017;Sun et al, 2017) which is even freely available from some sensors. MODIS, ASTER, Landsat ETM+, TM, OLI and Sentinel-2 MSI sensors can be used for surface velocity estimation.…”

Recent Surge Behavior of Walsh Glacier Revealed by Remote Sensing Data

“…Different solar illuminations, shadows, clouds, and snow-cover were the main sources of potential correlation failure. Although all of the Landsat images used were in the same path/row (063/017) to minimize the influences of geometric distortions and shadows [56], there were still some voids in the velocity maps resulting from correlation failure. In addition, clouds also forced us to choose some image pairs with longer intervals, thereby lowering the temporal resolution of the glacial velocity.…”

Impacts of Climate and Supraglacial Lakes on the Surface Velocity of Baltoro Glacier from 1992 to 2017

“…Though, in our case, the summer velocities from 2006 to 2008 had higher rates, as we used additional ALOS PALSAR-1 data from 2007 and 2008 covering the time period with higher surface velocities. Sun et al [3] analyzed the annual velocities over the central Karakoram for the period 1999-2003 using Landsat-7 ETM+ imagery and for the period 2007-2011, whereas the latter period has also been investigated by Rankl et al [10]. Sun et al [3] The last displacement result bases on ALOS PALSAR-2 data, which covers only the upstream part of the glacier.…”

“…Sun et al [3] analyzed the annual velocities over the central Karakoram for the period 1999-2003 using Landsat-7 ETM+ imagery and for the period 2007-2011, whereas the latter period has also been investigated by Rankl et al [10]. Sun et al [3] The last displacement result bases on ALOS PALSAR-2 data, which covers only the upstream part of the glacier. Due to different acquisition orbits, just a single acquisition is required to cover the whole Baltoro Glacier with ALOS PALSAR-1 data, whereas with ALOS PALSAR-2 data, at least four acquisitions are needed to ensure a full coverage of the glacier.…”