Temporal variations in supraglacial debris distribution on Baltoro Glacier, Karakoram between 2001 and 2012

Gibson, Morgan; Glasser, Neil F.; Quincey, Duncan J.; Mayer, C.; Rowan, Ann V.; Irvine‐Fynn, Tristram

doi:10.1016/j.geomorph.2017.08.012

Cited by 55 publications

(85 citation statements)

References 51 publications

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“…An obvious application of high-resolution thermal imagery is to inversely estimate debris-cover thickness (Mihalcea et al, 2008b;Foster et al, 2012;Rounce and McKinney, 2014;Schauwecker et al, 2015;Gibson et al, 2017;Kraaijenbrink et al, 2017), since thickness is an important variable in the surface energy balance of debris-covered glaciers (e.g., Benn, 2006, 2013;Ragettli et al, 2016). As we show in this study, the UAV is able to capture spatial patterns and heterogeneity in T s (Figures 7, 10).…”

Section: Applications Of Thermal Uav Imagerymentioning

confidence: 73%

Mapping Surface Temperatures on a Debris-Covered Glacier With an Unmanned Aerial Vehicle

et al. 2018

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A layer of debris cover often accumulates across the surface of glaciers in active mountain ranges with exceptionally steep terrain, such as the Andes, Himalaya, and New Zealand Alps. Such a supraglacial debris layer has a major influence on a glacier's surface energy budget, enhancing radiation absorption, and melt when the layer is thin, but insulating the ice when thicker than a few cm. Information on spatially distributed debris surface temperature has the potential to provide insight into the properties of the debris, its effects on the ice below and its influence on the near-surface boundary layer. Here, we deploy an unmanned aerial vehicle (UAV) equipped with a thermal infrared sensor on three separate missions over one day to map changing surface temperatures across the debris-covered Lirung Glacier in the Central Himalaya. We present a methodology to georeference and process the acquired thermal imagery, and correct for emissivity and sensor bias. Derived UAV surface temperatures are compared with distributed simultaneous in situ temperature measurements as well as with Landsat 8 thermal satellite imagery. Results show that the UAV-derived surface temperatures vary greatly both spatially and temporally, with −1.4 ± 1.8, 11.0 ± 5.2, and 15.3 ± 4.7 • C for the three flights (mean ± sd), respectively. The range in surface temperatures over the glacier during the morning is very large with almost 50 • C. Ground-based measurements are generally in agreement with the UAV imagery, but considerable deviations are present that are likely due to differences in measurement technique and approach, and validation is difficult as a result. The difference in spatial and temporal variability captured by the UAV as compared with much coarser satellite imagery is striking and it shows that satellite derived temperature maps should be interpreted with care. We conclude that UAVs provide a suitable means to acquire surface temperature maps of debris-covered glacier surfaces at high spatial and temporal resolution, but that there are caveats with regard to absolute temperature measurement.

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Section: Applications Of Thermal Uav Imagerymentioning

confidence: 73%

Mapping Surface Temperatures on a Debris-Covered Glacier With an Unmanned Aerial Vehicle

et al. 2018

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“…Rockfalls therefore play a significant, if not principal role in rockwall slope erosion, which is consistent with the observation that mass movements are a dominant mechanism for Himalayan landscape denudation (Gabet et al ., ; Dortch et al ., ; Lupker et al ., ). The frequency and magnitude of rockfall events over 10 3 −10 5 year timescales are likely controlled by regional erosion rates, which are moderated by climate and/or tectonism (Molnar et al ., ; Scherler et al ., ; Gibson et al ., ).…”

Section: Discussionmentioning

confidence: 99%

“…Past studies have quantified rockwall slope erosion by dating and estimating the volume of slope deposits such as talus (Andre, ; Curry and Morris, ; Hinchliffe and Ballantyne, ; Siewert et al ., ), or modeling supraglacial debris flux (Heimsath and McGlynn, ; Gibson et al ., ). More recently, rockwall slope erosion has been measured using cosmogenic 10 Be in medial moraine sediment (Heimsath and McGlynn, ; Seong et al ., ; Ward and Anderson, ; Scherler and Egholm, ).…”

Section: Methodsmentioning

confidence: 99%

“…For a given medial moraine sediment package, the shorter the duration of exposure of the source rockwall slopes to cosmic rays, the lower the accumulation of 10 Be, and the faster the inferred slope erosion rate. On sub‐millennial timescales the 10 Be concentrations are likely to reflect slope erosion via periglacial weathering processes, whereas over geomorphic timescales (10 3 −10 5 years) the input is more likely affected by local or regional erosion rates (Gibson et al ., ). We combine TCN methods with geomorphic and sedimentological analyses of Gangotri glacier medial moraines to constrain rates of rockwall slope erosion for the upper Bhagirathi catchment.…”

Section: Methodsmentioning

confidence: 99%

“…Periglacial weathering processes including freeze-thaw, frost cracking and ice wedging deliver large volumes of rockfall and avalanche debris to the mountain glacier sedimentary system from catchment slopes (Schroder et al, 2000;Matsuoka, 2001;Owen et al, 2003;Hales and Roering, 2005;Sanders et al, 2012;Gibson et al, 2017). The strength of coupling between rockwall slopes and glaciers affect glacier dynamics, catchment sediment flux and can dictate the relief and topographic configuration of catchment divides over time (Montgomery, 2002;Thiede et al, 2005;Moore et al, 2009).…”

Section: Introductionmentioning

confidence: 99%

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Rates of rockwall slope erosion in the upper Bhagirathi catchment, Garhwal Himalaya

Orr

Owen

Saha

et al. 2019

Earth Surf Processes Landf

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Rockwall slope erosion is defined for the upper Bhagirathi catchment using cosmogenic Beryllium‐10 (10Be) concentrations in sediment from medial moraines on Gangotri glacier. Beryllium‐10 concentrations range from 1.1 ± 0.2 to 2.7 ± 0.3 × 104 at/g SiO2, yielding rockwall slope erosion rates from 2.4 ± 0.4 to 6.9 ± 1.9 mm/a. Slope erosion rates are likely to have varied over space and time and responded to shifts in climate, geomorphic and/or tectonic regime throughout the late Quaternary. Geomorphic and sedimentological analyses confirm that the moraines are predominately composed of rockfall and avalanche debris mobilized from steep relief rockwall slopes via periglacial weathering processes. The glacial rockwall slope erosion affects sediment flux and storage of snow and ice at the catchment head on diurnal to millennial timescales, and more broadly influences catchment configuration and relief, glacier dynamics and microclimates. The slope erosion rates exceed the averaged catchment‐wide and exhumation rates of Bhagirathi and the Garhwal region on geomorphic timescales (103−105 years), supporting the view that erosion at the headwaters can outpace the wider catchment. The 10Be concentrations of medial moraine sediment for the upper Bhagirathi catchment and the catchments of Chhota Shigri in Lahul, northern India and Baltoro glacier in Central Karakoram, Pakistan show a tentative relationship between 10Be concentration and precipitation. As such there is more rapid glacial rockwall slope erosion in the monsoon‐influenced Lesser and Greater Himalaya compared to the semi‐arid interior of the orogen. Rockwall slope erosion in the three study areas, and more broadly across the northwest Himalaya is likely governed by individual catchment dynamics that vary across space and time. © 2019 The Authors. Earth Surface Processes and Landforms Published by John Wiley & Sons, Ltd.

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Evolution of debris cover on glaciers of the Eastern Alps, Austria, between 1996 and 2015

Fleischer

Otto

Junker

et al. 2021

Earth Surf Processes Landf

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Debris cover on glaciers is an important component of glacial systems as it influences climate–glacier dynamics and thus the lifespan of glaciers. Increasing air temperatures, permafrost thaw and rock faces freshly exposed by glacier downwasting in accumulation zones result in increased rockfall activity and debris input. In the ablation zone, negative mass balances result in an enhanced melt‐out of englacial debris. Glacier debris cover thus represents a clear signal of climate warming in mountain areas. To assess the temporal development of debris on glaciers of the Eastern Alps, Austria, we mapped debris cover on 255 glaciers using Landsat data at three time steps. We applied a ratio‐based threshold classification technique and analysed glacier catchment characteristics to understand debris sources better. Across the Austrian Alps, debris cover increased by more than 10% between 1996 and 2015 while glaciers retreated in response to climate warming. Debris cover distribution shows significant regional variability, with some mountain ranges being characterised by mean debris cover on glaciers of up to 75%. We also observed a general rise of the mean elevation of debris cover on glaciers in Austria. The debris cover distribution and dynamics are highly variable due to topographic, lithological and structural settings that determine the amount of debris delivered to and stored in the glacier system. Despite strong variation in debris cover, all glaciers investigated melted at increasing rates. We conclude that the retarding effects of debris cover on the mass balance and melt rate of Austrian glaciers is strongly subdued compared with other mountain areas. The study indicates that, if this trend continues, many glaciers in Austria may become fully debris covered. However, since debris cover seems to have little impact on melt rates, this would not lead to prolonged existence of debris‐covered ice compared with clean ice glaciers.

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Temporal variations in supraglacial debris distribution on Baltoro Glacier, Karakoram between 2001 and 2012

Cited by 55 publications

References 51 publications

Mapping Surface Temperatures on a Debris-Covered Glacier With an Unmanned Aerial Vehicle

Mapping Surface Temperatures on a Debris-Covered Glacier With an Unmanned Aerial Vehicle

Rates of rockwall slope erosion in the upper Bhagirathi catchment, Garhwal Himalaya

Evolution of debris cover on glaciers of the Eastern Alps, Austria, between 1996 and 2015

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