A Glacier Surge of Bivachny Glacier, Pamir Mountains, Observed by a Time Series of High-Resolution Digital Elevation Models and Glacier Velocities

Abstract

Surge-type glaciers are characterised by relatively short phases of enhanced ice transport and mass redistribution after a comparatively long quiescent phase when the glacier is virtually inactive. This unstable behaviour makes it difficult to assess the influence of climate change on those glaciers. We describe the evolution of the most recent surge of Bivachny Glacier in the Pamir Mountains, Tajikistan between 2011 and 2015 with respect to changes in its topography and dynamics. For the relevant time span, nine digital elevation models were derived from TanDEM-X data; optical satellite data (Landsat 5, 7 and 8, EO-1) as well as synthetic aperture radar data (TerraSAR-X and TanDEM-X) were used to analyse ice flow velocities. The comparison of the topography at the beginning of the surge with the one observed by the Shuttle Radar Topography Mission in 2000 revealed a thickening in the upper part of the ablation area of the glacier and a thinning further down the glacier as is typically observed during the quiescent phase. During the active phase, a surge bulge measuring up to around 80 m developed and travelled downstream for a distance of 13 km with a mean velocity of 4400 m year −1 . Ice flow velocities increased from below 90 m year −1 duringthe quiescent phase in 2000 to up to 3400 m year −1 in spring 2014. After reaching the confluence with Fedchenko Glacier, the surge slowed down until it completely terminated in 2015. The observed seasonality of the glacier velocities with a regular speed-up during the onset of the melt period suggests a hydrological control of the surge related to the effectiveness of the subglacial drainage system.

The Possible Transition From Glacial Surge to Ice Stream on Vavilov Ice Cap

“…The pattern of glacier speed has also evolved (Figures 2a-2d, S3, and Movie S1). In 2016/2017, the maximum speed appears at the boundary of reservoir/receiving zone near the ELA, which is typical for a glacier surge (Fu et al, 2019;Nuth et al, 2019;Wendt et al, 2017). However, during the 2018 speedup event the maximum speed is observed near the terminus.…”

Status and Change of the Cryosphere in the Extended Hindu Kush Himalaya Region

“…Despite significant recent progress through remote-sensing/field measurements (Immerzeel et al 2014) and model studies of the complex coupled system of debris, ice cliffs, and ponds (Miles et al 2016;Buri et al 2016; Banerjee 2017), significant challenges still remain in understanding these glaciers: we cannot yet predict the long-term changes in the debris cover area or thickness, or the effect of such changes on the future of glaciers and their meltwater production at the scale of the whole Himalaya. Frequent surges and contrasting length changes are not only common in the Karakoram but also in central and northeast Pamir (Dolgoushin and Osipova 1975;Kotlyakov et al 2008;Osipova and Khromova 2010;Holzer et al 2016;Wendt et al 2017), and a recent surge was also reported in eastern Pamir (Shangguan et al 2016). In contrast to the Karakoram, however, existing studies on glacier area and length changes suggest a continuous area loss in northeastern and central Pamir.…”

A consistent glacier inventory for Karakoram and Pamir derived from Landsat data: distribution of debris cover and mapping challenges

“…In the western Pamir, glacier volume evolution seems to be more negative, but is for the first decade of the 2000s still relatively modest (Brun et al, 2017); moreover, satellite images of the past two decades reveal that many glaciers in this region have surged (e.g. Wendt et al, 2017). However, many of the non-surge-type glaciers in the Pamir have been continuously retreating and losing area 1810 N. Mölg et al: Inventory of glaciers and debris cover for Karakoram and Pamir (Holzer et al, 2016;Khromova et al, 2006;Shangguan et al, 2006).…”

“…In contrast to this definition, the surging Bivachny glacier tongue was separated from Fedchenko glacier in the confluence region although one can argue that Bivachny is a connected feeder (see Fig. 6 in Wendt et al, 2017). A size filter of 0.02 km 2 was applied to remove small seasonal snowfields and remaining noise.…”