Radio Echo Soundings and Ice-Temperature Measurements in a Surge-Type Glacier

Goodman, R. H.

doi:10.1017/s002214300001340x

Cited by 41 publications

(23 citation statements)

References 6 publications

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“…Drainage of basal water and conductive cooling return the glacier to its initial state, whereupon the cycle can begin once more. It has long been recognized that the existence of temperate surging glaciers means that thermal instability cannot provide a general explanation of all surges [Clarke, 1976;Clarke and Goodman, 1975;Jarvis and Clarke, 1975], although thermal instability remains a viable surge mechanism for glaciers with basal temperatures near the melting point.…”

Section: Introductionmentioning

confidence: 99%

Thermal structure of Svalbard glaciers and implications for thermal switch models of glacier surging

et al. 2015

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Switches between cold‐ and warm‐based conditions have long been invoked to explain surges of High Arctic glaciers. Here we compile existing and new data on the thermal regime of six glaciers in Svalbard to test the applicability of thermal switch models. Two of the large glaciers of our sample are water terminating while one is land terminating. All three have a well‐known surge history. They have a thick basal layer of temperate ice, superimposed by cold ice. A cold terminus forms during quiescence but is mechanically removed by calving on tidewater glaciers. The other three glaciers are relatively small and are either entirely cold or have a diminishing warm core. All three bear evidence of former warm‐based thermal regimes and, in two cases, surge‐like behavior during the Little Ice Age. In Svalbard, therefore, three types of glaciers have switched from slow to fast flow: (1) small glaciers that underwent thermal cycles during and following the Little Ice Age (switches between cold‐ and warm‐based conditions), (2) large terrestrial glaciers which remain warm based throughout the entire surge cycle but develop cold termini during quiescence, and (3) large tidewater glaciers that remain warm based throughout the surge cycle. Our results demonstrate that thermal switching cannot explain the surges of large glaciers in Svalbard. We apply the concept of enthalpy cycling to the spectrum of surge and surge‐like behavior displayed by these glaciers and demonstrate that all Svalbard surge‐type glaciers can be understood within a single conceptual framework.

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Section: Introductionmentioning

confidence: 99%

Thermal structure of Svalbard glaciers and implications for thermal switch models of glacier surging

et al. 2015

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“…In all mountainous glaciated area, polythermal structures can be observed on glaciers. Many studies have described this kind of glacier in the Alps [ Eisen et al , 2009], Greenland [ Loewe , 1966], Alaska [ Rabus and Echelmeyer , 2002; Harrison et al , 1975], the Rockies [ Paterson , 1972; Clarke and Goodman , 1975], the Himalayas [ Maohuan , 1990; Gulley et al , 2009], the Peri‐Antarctic Islands [ Navarro et al , 2009], the Canadian Arctic [ Copland et al , 2003; Blatter , 1987], Svalbard [ Jania et al , 1996; Ødegard et al , 1992; Rippin et al , 2005], and the Scandinavian mountains [ Holmlund and Eriksson , 1989]. In fact, all glaciers with wet accumulation areas [ Paterson , 1994] and ablation areas with a mean annual temperature below zero are polythermal with a temperate accumulation area and a partially cold ablation area.…”

Section: Introductionmentioning

confidence: 99%

The influence of snow cover thickness on the thermal regime of Tête Rousse Glacier (Mont Blanc range, 3200 m a.s.l.): Consequences for outburst flood hazards and glacier response to climate change

et al. 2012

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Tête Rousse Glacier (French Alps) was responsible for an outburst flood in 1892 that devastated the village of St Gervais‐Le Fayet close to Chamonix, causing 175 fatalities. Changes in the hydrothermal configuration of the glacier are suspected to be the cause of this catastrophic outburst flood. In 2010, geophysical surveys of this glacier revealed a subglacial lake that was subsequently drained artificially. The processes controlling the thermal regime of the glacier have been investigated on the basis of measurements and snow/firn cover and heat flow models using meteorological data covering the last 200 years. Temperature measurements show a polythermal structure with subglacial water trapped by the cold lowest part of the glacier (−2°C). The modeling approach shows that the polythermal structure is due to temporal changes in the depth of the snow/firn cover at the glacier surface. Paradoxically, periods with negative mass balances, associated with warmer air temperature, tend to cool the glacier, whereas years with colder temperatures, associated with positive mass balances, tend to increase the glacier temperature by increasing the firnpack depth and extent. The thermal effect of the subglacial lake is evaluated and shows that the lake was formed around 1980. According to future climate scenarios, modeling shows that the glacier may cool again in the future. This study provides insights into the thermal processes responsible for water storage inside a small almost static glacier, which can lead to catastrophic outburst floods such as the 1892 event or potentially dangerous situations as in 2010.

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“…This lack of generality has led to some disregard for thermal regulation as a control for glacier surges. Despite this, many authors acknowledge that the thermal regime must influence surging (Clarke and Goodman, 1975; Clarke, 1976), and indeed the presence of an internal radio-echo sounding reflector (believed to be a surrogate for a polythermal regime) seems to be related to the occurrence of glacier surging in Svalbard (Hamilton and Dowdeswell, 1996; Jiskoot and others, 2000).…”

Section: Introductionmentioning

confidence: 99%

Thermally controlled glacier surging

Fowler

Murray²,

2001

J. Glaciol.

172

181

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Bakaninbreen in Svalbard and Trapridge Glacier in Yukon Territory, Canada, are two prominent examples of surging glaciers which are thought to be controlled by their thermal regime. Both glaciers have developed large bulges which have propagated forward as travelling wave fronts, and which are thought to divide relatively stagnant downstream cold-based ice from faster-moving warm-based upstream ice. Additionally, both glaciers are underlain by a wet, metres thick layer of deforming till. We develop a simple model for the cyclic surging behaviour of these glaciers, which interrelates the motion of the ice and till through a description of the subglacial hydrology. We find that oscillations (surges) can occur if the subglacial hydrological transmissivity is sufficiently low and the till layer is sufficiently thin, and we suggest that these oscillations are associated with the development and propagation of a travelling wave front down the glacier. We therefore interpret the travelling wave fronts on both Trapridge Glacier and Bakaninbreen as manifestations of surges. In addition, we find that the violence of the surge in the model is associated with the resistance to ice flow offered by undulations in the bed, and the efficiency with which occasional hydrological events can release water accumulated at the glacier sole.

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Radio Echo Soundings and Ice-Temperature Measurements in a Surge-Type Glacier

Cited by 41 publications

References 6 publications

Thermal structure of Svalbard glaciers and implications for thermal switch models of glacier surging

Thermal structure of Svalbard glaciers and implications for thermal switch models of glacier surging

The influence of snow cover thickness on the thermal regime of Tête Rousse Glacier (Mont Blanc range, 3200 m a.s.l.): Consequences for outburst flood hazards and glacier response to climate change

Thermally controlled glacier surging

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