Multiannual observations and modelling of seasonal thermal profiles through supraglacial debris in the Central Himalaya

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Multiannual observations and modelling of seasonal thermal profiles through supraglacial debris in the Central Himalaya. / Rowan, Ann V.; Nicholson, Lindsey; Collier, Emily; Quincey, Duncan J.; Gibson, Morgan; Wagnon, Patrick; Irvine-Fynn, Tristram; Glasser, Neil.

In: Cryosphere Discussions, 30.11.2017.

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Rowan AV, Nicholson L, Collier E, Quincey DJ, Gibson M, Wagnon P et al. Multiannual observations and modelling of seasonal thermal profiles through supraglacial debris in the Central Himalaya. Cryosphere Discussions. 2017 Nov 30. https://doi.org/10.5194/tc-2017-239

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Rowan, Ann V. ; Nicholson, Lindsey ; Collier, Emily ; Quincey, Duncan J. ; Gibson, Morgan ; Wagnon, Patrick ; Irvine-Fynn, Tristram ; Glasser, Neil. / Multiannual observations and modelling of seasonal thermal profiles through supraglacial debris in the Central Himalaya. In: Cryosphere Discussions. 2017.

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@article{75e8ea48093643749fec619f098b4875,
title = "Multiannual observations and modelling of seasonal thermal profiles through supraglacial debris in the Central Himalaya",
abstract = "Many glaciers in the Central Himalaya are covered with rock debris that modifies the transfer of heat from the atmosphere to the underlying ice. These debris-covered glaciers are experiencing rapid mass loss at rates that have accelerated during the last two decades. Quantifying recent and future glacier mass change requires understanding the relationship between debris thickness and ablation particularly through the summer monsoon season. We present air, near-surface and debris temperatures measured during three monsoon seasons at five sites on Khumbu Glacier in Nepal, and compare these results to similar measurements from two other debris-covered glaciers in this region. Seasonal debris temperature profiles are approximately linear and consistent between sites for thick (> 0.5 m) and thin (< 0.5 m) debris across thicknesses ranging from 0.26 to 2.0 m. The similarities between these multiannual data imply that they are representative of supraglacial debris layers in the monsoon-influenced Himalaya more generally. We compare three methods to calculate sub-debris ablation, including using our temperature measurements with a thermal diffusion model that incorporates a simplified treatment of debris moisture. Estimated ablation between 3 June and 11 October at around 5000 m above sea level ranged from 0.10 m water equivalent beneath 1.5 m of debris to 0.47 m water equivalent beneath 0.3 m debris. However, these values are small when compared to remotely observed rates of surface lowering, suggesting that mass loss from these debris-covered glaciers is greatly enhanced by supraglacial and englacial processes that locally amplify ablation",
author = "Rowan, {Ann V.} and Lindsey Nicholson and Emily Collier and Quincey, {Duncan J.} and Morgan Gibson and Patrick Wagnon and Tristram Irvine-Fynn and Neil Glasser",
year = "2017",
month = nov,
day = "30",
doi = "10.5194/tc-2017-239",
language = "English",
journal = "Cryosphere Discussions",
issn = "1994-0432",
publisher = "Copernicus Publications",

}

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TY - JOUR

T1 - Multiannual observations and modelling of seasonal thermal profiles through supraglacial debris in the Central Himalaya

AU - Rowan, Ann V.

AU - Nicholson, Lindsey

AU - Collier, Emily

AU - Quincey, Duncan J.

AU - Gibson, Morgan

AU - Wagnon, Patrick

AU - Irvine-Fynn, Tristram

AU - Glasser, Neil

PY - 2017/11/30

Y1 - 2017/11/30

N2 - Many glaciers in the Central Himalaya are covered with rock debris that modifies the transfer of heat from the atmosphere to the underlying ice. These debris-covered glaciers are experiencing rapid mass loss at rates that have accelerated during the last two decades. Quantifying recent and future glacier mass change requires understanding the relationship between debris thickness and ablation particularly through the summer monsoon season. We present air, near-surface and debris temperatures measured during three monsoon seasons at five sites on Khumbu Glacier in Nepal, and compare these results to similar measurements from two other debris-covered glaciers in this region. Seasonal debris temperature profiles are approximately linear and consistent between sites for thick (> 0.5 m) and thin (< 0.5 m) debris across thicknesses ranging from 0.26 to 2.0 m. The similarities between these multiannual data imply that they are representative of supraglacial debris layers in the monsoon-influenced Himalaya more generally. We compare three methods to calculate sub-debris ablation, including using our temperature measurements with a thermal diffusion model that incorporates a simplified treatment of debris moisture. Estimated ablation between 3 June and 11 October at around 5000 m above sea level ranged from 0.10 m water equivalent beneath 1.5 m of debris to 0.47 m water equivalent beneath 0.3 m debris. However, these values are small when compared to remotely observed rates of surface lowering, suggesting that mass loss from these debris-covered glaciers is greatly enhanced by supraglacial and englacial processes that locally amplify ablation

AB - Many glaciers in the Central Himalaya are covered with rock debris that modifies the transfer of heat from the atmosphere to the underlying ice. These debris-covered glaciers are experiencing rapid mass loss at rates that have accelerated during the last two decades. Quantifying recent and future glacier mass change requires understanding the relationship between debris thickness and ablation particularly through the summer monsoon season. We present air, near-surface and debris temperatures measured during three monsoon seasons at five sites on Khumbu Glacier in Nepal, and compare these results to similar measurements from two other debris-covered glaciers in this region. Seasonal debris temperature profiles are approximately linear and consistent between sites for thick (> 0.5 m) and thin (< 0.5 m) debris across thicknesses ranging from 0.26 to 2.0 m. The similarities between these multiannual data imply that they are representative of supraglacial debris layers in the monsoon-influenced Himalaya more generally. We compare three methods to calculate sub-debris ablation, including using our temperature measurements with a thermal diffusion model that incorporates a simplified treatment of debris moisture. Estimated ablation between 3 June and 11 October at around 5000 m above sea level ranged from 0.10 m water equivalent beneath 1.5 m of debris to 0.47 m water equivalent beneath 0.3 m debris. However, these values are small when compared to remotely observed rates of surface lowering, suggesting that mass loss from these debris-covered glaciers is greatly enhanced by supraglacial and englacial processes that locally amplify ablation

U2 - 10.5194/tc-2017-239

DO - 10.5194/tc-2017-239

M3 - Article

JO - Cryosphere Discussions

JF - Cryosphere Discussions

SN - 1994-0432

ER -

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