Flow and structure in a dendritic glacier with bedrock steps

Jiskoot, Hester; Fox, T. A.; Wychen, Wesley Van

doi:10.1017/jog.2017.58

Cited by 14 publications

(23 citation statements)

References 86 publications

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“…Thus, there are three segments of velocity pattern that are mostly controlled by incoming flow from tributaries (c.f. Bhambri and others, 2017; Jiskoot and others, 2017).…”

Section: Resultsmentioning

confidence: 96%

Interannual modulation of seasonal glacial velocity variations in the Eastern Karakoram detected by ALOS-1/2 data

Usman

Furuya

2018

J. Glaciol.

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Unlike in most other regions, Karakoram glaciers are either stable or advancing, a phenomenon known as the Karakoram anomaly. Despite studies of glacier surges and the derivation of surface velocity maps, the spatiotemporal variability of glacier dynamics still remains poorly understood, particularly in the Eastern Karakoram Range. We use Advanced Land Observing Satellite/the Phased Array type L-band Synthetic Aperture Radar (ALOS/PALSAR)-1/2 data from 2007 to 2011 and 2014 to 2015 to examine detailed surface velocity patterns of the Siachen, Baltoro, Kundos, Singkhu and Gasherbrum Glaciers. The first three glaciers show considerable velocity variability (20–350 m a−1), with clear seasonal patterns. Although all glaciers, except for Baltoro, flow slowest in 2015, the velocity structures are individual and vary in space and time. In Gasherbrum Glacier, peak surge-phase velocities are seasonally modulated, with maxima in summers 2006 and 2007, suggesting surface melt plays an important role in maintaining the active phase. Given the relatively close proximity of these glaciers, we assume that surface melt timing and rates are comparable. We therefore argue that the observed spatiotemporal and interannual velocity patterns are determined by local and internal mechanisms, including englacial and subglacial hydrology, thermal processes and tributary configuration of each individual glacier.

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“…Thus, there are three segments of velocity pattern that are mostly controlled by incoming flow from tributaries (c.f. Bhambri and others, 2017; Jiskoot and others, 2017).…”

Section: Resultsmentioning

confidence: 96%

Interannual modulation of seasonal glacial velocity variations in the Eastern Karakoram detected by ALOS-1/2 data

Usman

Furuya

2018

J. Glaciol.

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“…Satellite remote sensing imagery has allowed the structure of large ice masses to be investigated, including ice shelves and ice streams (e.g., Ely & Clark, 2016;Ely et al, 2017;Fahnestock et al, 2000;Glasser & Gudmundsson, 2012;Glasser & Scambos, 2008;Glasser et al, 2015;Hambrey & Dowdeswell, 1994;Reynolds & Hambrey, 1988). Of indirect value to interpreting structures is the use of satellite data to quantify the dynamics of ice masses, including interferometry, feature-tracking, and speckle-tracking (e.g., Jiskoot et al, 2017;Luckman et al, 2002;Mansell et al, 2012;Medrzycka et al, 2019;Pritchard et al, 2005;Quincey et al, 2009). Another remote-sensing technique which is in the early stages of implementation in glacier studies is Light Detection and Ranging (LiDAR), as reviewed for the cryosphere by Bhardwaj et al (2016).…”

Section: Structural Glaciological Analytical Methodsmentioning

confidence: 99%

“…Extending flow above and within an icefall is followed by compressive flow at the base, and the resulting structural assemblage differs markedly from that described in Section 6.1. Well-studied examples include Griesgletscher and Bas Glacier d'Arolla in the Swiss Alps (Table 1), Blue Glacier in Washington State (Allen et al, 1960), Gulkana Glacier in Alaska (Ragan, 1969), Pasterzenkees in the Austrian Alps (Herbst & Neubauer, 2000), Kvíárjökull in Iceland (Phillips et al, 2017;Swift & Jones, 2018), Soler Glacier in the Northern Patagonian Icefield (Aniya & Naruse, 1987;Aniya et al, 1988), and Shackleton Glacier in the Canadian Rockies (Jiskoot et al, 2017). Severe recession of these glaciers has meant that many of the features described in the earlier (pre-2010) studies have now disappeared.…”

Section: Structural Assemblage Dominated By Icefall Processesmentioning

confidence: 99%

“…Five main groups of crevasse types were identified: (a) arcuate upglacier and transverse crevasses in zones of longitudinal extension as the ice approached an icefall and where the main trunk narrowed; (b) longitudinal and splaying crevasses indicative of lateral extension at the base of the icefalls; (c) short marginal crevasses forming at angle of 45° to the margins in zones of uniform velocity; (d) longer, upward-splaying crevasses where the glacier trunk enters a valley constriction and zone of longitudinal compressive flow; and (e) chevron and en echelon crevasses in rotating marginal bends. The SPOT imagery also allowed digitization of the density of crevasses to be determined (Jiskoot et al, 2017).…”

Section: Shackleton Glacier Canadian Rockiesmentioning

confidence: 99%

“…The largest temperate glacier in the Canadian Rockies, covering 40 km 2 , is Shackleton Glacier. It has a complex morphology, characterized by multiple flow units, a channel that fluctuates in width, bedrocks steps, and multiple icefalls (Jiskoot et al, 2017). A range of structures were identified, including crevasses, crevasse traces, ogives, longitudinal foliation, folded foliation, and thrust-faults.…”

Section: Shackleton Glacier Canadian Rockiesmentioning

confidence: 99%

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Structures and Deformation in Glaciers and Ice Sheets

Jennings

Hambrey

2021

Reviews of Geophysics

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The purpose of this review is to provide a comprehensive assessment of the state of knowledge concerning the manner in which macroscopic structures evolve within glaciers, and to evaluate their meaning in terms of understanding the flow of glaciers and ice sheets. Using concepts drawn from structural geology (e.g., Fossen, 2010;Hobbs et al., 1976;Ramsay, 1967;Ramsay & Huber, 1983), attention is drawn to the similarities between glacier ice and deformed rocks. The review emphasizes those structures that can be observed at the glacier surface and considers their three-dimensional (3-D) geometry. Structures in glaciers are commonly complex and challenging to interpret, especially where several phases of deformation over-print one another. Hence, to aid the reader in the field, many of the described structures and their cross-cutting relationships are illustrated in photographs, maps, and conceptual diagrams, with examples ranging from the Arctic, through mid-latitude mountain ranges, to the Antarctic.

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Topographic controls on ice flow and recession for Juneau Icefield (Alaska/British Columbia)

Davies

Bendle

Carrivick

et al. 2022

Earth Surf Processes Landf

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Globally, mountain glaciers and ice caps are losing dramatic volumes of ice. The resultant sea‐level rise is dominated by contributions from Alaska. Plateau icefields may be especially sensitive to climate change due to the non‐linear controls their topography imparts on their response to climate change. However, Alaskan plateau icefields have been subject to little structural glaciological or regional geomorphological assessment, which makes the controls on their present and former mass balance difficult to ascertain. We inventoried 1050 glaciers and 368 lakes in the Juneau Icefield region for the year 2019. We found that 63 glaciers had disappeared since the 2005 inventory, with a reduction in glacier area of 422 km2 (10.0%). We also present the first structural glaciological and geomorphological map for an entire icefield in Alaska. Glaciological mapping of >20 800 features included crevasses, debris cover, foliation, ogives, medial moraines and, importantly, areas of glacier fragmentation, where glaciers either separated from tributaries via lateral recession (n = 59), or disconnected within areas of former icefalls (n = 281). Geomorphological mapping of >10 200 landforms included glacial moraines, glacial lakes, trimlines, flutes and cirques. These landforms were generated by a temperate icefield during the Little Ice Age (LIA) neoglaciation. These data demonstrate that the present‐day outlet glaciers, which have a similar thermal and ice‐flow regime, have undergone largely continuous recession since the LIA. Importantly, disconnections occurring within glaciers can separate accumulation and ablation zones, increasing rates of glacier mass loss. We show that glacier disconnections are widespread across the icefield and should be critically taken into consideration when icefield vulnerability to climate change is considered.

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Flow and structure in a dendritic glacier with bedrock steps

Cited by 14 publications

References 86 publications

Interannual modulation of seasonal glacial velocity variations in the Eastern Karakoram detected by ALOS-1/2 data

Interannual modulation of seasonal glacial velocity variations in the Eastern Karakoram detected by ALOS-1/2 data

Structures and Deformation in Glaciers and Ice Sheets

Topographic controls on ice flow and recession for Juneau Icefield (Alaska/British Columbia)

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