The climate memory of an Arctic polythermal glacier

Delcourt, Charlotte; Liefferinge, Brice Van; Nolan, M.; Pattyn, Frank

doi:10.3189/2013jog12j109

Cited by 6 publications

(7 citation statements)

References 42 publications

(77 reference statements)

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“…McCall Glacier is a polythermal valley glacier in the eastern Brooks Range (69°3′N, 143°8′W), northeast Alaska (Klok and others, 2005; Delcourt and others, 2013) (Figs 2a, b). It covers an area of about 6.35 km 2 with a maximum flow line distance of 7200 m over an elevation range from 1375 to 2635 m above sea level (m a.s.l.)…”

Section: Study Sitementioning

confidence: 99%

Modelling spatial patterns of near-surface air temperature over a decade of melt seasons on McCall Glacier, Alaska

Troxler

Ayala²,

Shaw

et al. 2020

J. Glaciol.

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We examine the spatial patterns of near-surface air temperature (Ta) over a melting glacier using a multi-annual dataset from McCall Glacier, Alaska. The dataset consists of a 10-year (2005–2014) meteorological record along the glacier centreline up to an upper glacier cirque, spanning an elevation difference of 900 m. We test the validity of on-glacier linear lapse rates, and a model that calculates Ta based on the influence of katabatic winds and other heat sources along the glacier flow line. During the coldest hours of each summer (10% of time), average lapse rates across the entire glacier range from −4.7 to −6.7°C km−1, with a strong relationship between Ta and elevation (R2 > 0.7). During warm conditions, Ta shows more complex, non-linear patterns that are better explained by the flow line-dependent model, reducing errors by up to 0.5°C compared with linear lapse rates, although more uncertainty might be associated with these observations due to occasionally poor sensor ventilation. We conclude that Ta spatial distribution can vary significantly from year to year, and from one glacier section to another. Importantly, extrapolations using linear lapse rates from the ablation zone might lead to large underestimations of Ta on the upper glacier areas.

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Section: Study Sitementioning

confidence: 99%

Modelling spatial patterns of near-surface air temperature over a decade of melt seasons on McCall Glacier, Alaska

Troxler

Ayala²,

Shaw

et al. 2020

J. Glaciol.

Self Cite

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“…The mass loss coincidentally started to stabilize as the terminus was nearing this riegel, highlighting the role of the glacier's basal topography on the retreat of its terminus. The thinning of a polythermal glacier can also make its tongue colder and thus slower (Delcourt et al 2013), possibly further constricting the flow of ice past the riegel, which might have hindered the lowermost parts of the glacier from being replenished in the 1900s. The glacier's basal topography, together with a warming climate, are therefore both likely causes of its strong melt in the first half of the 1900s.…”

Section: Discussionmentioning

confidence: 99%

Constraining 135 years of mass balance with historic structure-from-motion photogrammetry on Storglaciären, Sweden

Holmlund

2019

Geografiska Annaler: Series A, Physical Geography

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Geodetic volume estimates of Storglaciären in Sweden suggest a 28% loss in total ice mass between 1910 and 2015. Terrestrial photographs from 1910 of Tarfala valley, where Storglaciären is situated, allow for an accurate reconstruction of the glacier's surface using Structure-from-Motion photogrammetry, which we used for past volume and mass estimations. The glacier's yearly mass balance gradient and net mass balance was also estimated back to 1880 using weather data from Karesuando, 170 km northeast of Storglaciären, through neural network regression. These combined reconstructions provide a continuous mass change series between the end of the Little Ice Age and 1946, when field data become available. The resultant reconstruction suggests a state close to equilibrium between 1880 and the 1910s, followed by drastic melt until the 1970s, constituting 76% of the 1910-2015 ice loss. More favourable conditions subsequently stabilized the mass balance until the late 1990s, after which Storglaciären started losing mass again. The 1910 reconstruction allows for a more accurate mass change series than previous estimates, and the methodology can be used on other glaciers where early photographic material exists.

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“…In many glacierized regions, atmospheric warming, rising snowlines, and expanding ablation areas may result in extensive supraglacial hydrology even as total glacier areas decline. Similarly, glacier thinning and cooling in higher latitudes (e.g., Delcourt, Liefferinge, Nola, & Pattyn, ; Irvine‐Fynn, Hodson, et al, ) may also promote an increasing dominance of supraglacial hydrology. Consequently, understanding the influence that the weathering crust has on modulating supraglacial run‐off and its characteristics is important to improve predictive hydrological models.…”

Section: Discussionmentioning

confidence: 99%

Section: Hydrological Role Of the Weathering Crust And Relevance Tomentioning

confidence: 99%

Near‐surface hydraulic conductivity of northern hemisphere glaciers

Stevens

Irvine‐Fynn

Porter

et al. 2018

Hydrological Processes

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The hydrology of near‐surface glacier ice remains a neglected aspect of glacier hydrology despite its role in modulating meltwater delivery to downstream environments. To elucidate the hydrological characteristics of this near‐surface glacial weathering crust, we describe the design and operation of a capacitance‐based piezometer that enables rapid, economical deployment across multiple sites and provides an accurate, high‐resolution record of near‐surface water‐level fluctuations. Piezometers were employed at 10 northern hemisphere glaciers, and through the application of standard bail–recharge techniques, we derive hydraulic conductivity (K) values from 0.003 to 3.519 m day−1, with a mean of 0.185 ± 0.019 m day−1. These results are comparable to those obtained in other discrete studies of glacier near‐surface ice, and for firn, and indicate that the weathering crust represents a hydrologically inefficient aquifer. Hydraulic conductivity correlated positively with water table height but negatively with altitude and cumulative short‐wave radiation since the last synoptic period of either negative air temperatures or turbulent energy flux dominance. The large range of K observed suggests complex interactions between meteorological influences and differences arising from variability in ice structure and crystallography. Our data demonstrate a greater complexity of near‐surface ice hydrology than hitherto appreciated and support the notion that the weathering crust can regulate the supraglacial discharge response to melt production. The conductivities reported here, coupled with typical supraglacial channel spacing, suggest that meltwater can be retained within the weathering crust for at least several days. Not only does this have implications for the accuracy of predictive meltwater run‐off models, but we also argue for biogeochemical processes and transfers that are strongly conditioned by water residence time and the efficacy of the cascade of sediments, impurities, microbes, and nutrients to downstream ecosystems. Because continued atmospheric warming will incur rising snowline elevations and glacier thinning, the supraglacial hydrological system may assume greater importance in many mountainous regions, and consequently, detailing weathering crust hydraulics represents a research priority because the flow path it represents remains poorly constrained.

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The climate memory of an Arctic polythermal glacier

Cited by 6 publications

References 42 publications

Modelling spatial patterns of near-surface air temperature over a decade of melt seasons on McCall Glacier, Alaska

Modelling spatial patterns of near-surface air temperature over a decade of melt seasons on McCall Glacier, Alaska

Constraining 135 years of mass balance with historic structure-from-motion photogrammetry on Storglaciären, Sweden

Near‐surface hydraulic conductivity of northern hemisphere glaciers

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