Helheim Glacier ice velocity variability responds to runoff and terminus position change at different timescales

Ultee, Lizz; Felikson, Denis; Minchew, Brent; Stearns, L. A.; Riel, Bryan

doi:10.1038/s41467-022-33292-y

Cited by 10 publications

(14 citation statements)

References 101 publications

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“…This is in some contrast to Ultee et al. (2022), who concluded that on seasonal timescales, Helheim was primarily runoff‐driven, and Bevan et al. (2015), who also found a link between runoff and seasonal surface elevation change.…”

Section: Discussioncontrasting

confidence: 69%

“…(2018) studied three points within 30 km of the terminus, while Ultee et al. (2022) studied 23 points at 1 km spacing on Helheim Glacier, and six points within ∼20 km of the terminus were analyzed at Jakobshavn Glacier by Joughin et al. (2012, 2019), at Helheim and Kangerdlussuaq Glaciers by Kehrl et al.…”

Section: Introductionmentioning

confidence: 99%

“…Usually, analyses of many glaciers study a single site at each glacier (Moon et al, 2014;Sakakibara & Sugiyama, 2019;Vijay et al, 2019Vijay et al, , 2021, while analyses that focus on a smaller number of large glaciers study ice flow at two to eight points along a flowline. For instance, at Zachariae Ice Stream, Lemos et al (2018) studied three points within 30 km of the terminus, while Ultee et al (2022) studied 23 points at 1 km spacing on Helheim Glacier, and six points within ∼20 km of the terminus were analyzed at Jakobshavn Glacier by Joughin et al (2012Joughin et al ( , 2019, at Helheim and Kangerdlussuaq Glaciers by Kehrl et al (2017), and at three glaciers feeding Godthabsfjord by Davison et al (2020). At all these glaciers, the seasonal variations in ice flow were synchronous across all study points, with more muted variability inland that was in phase with the variability nearer the terminus.…”

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confidence: 99%

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Seasonal Flow Types of Glaciers in Sermilik Fjord, Greenland, Over 2016–2021

Poinar

2023

JGR Earth Surface

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Greenland glaciers have three primary seasonal ice flow patterns, or “types”: terminus‐driven, runoff‐driven, and runoff‐adapting. To date, glacier types have been identified by analyzing flow at a single location near the terminus; information at all other locations is discarded. Here, we use principal component (PC)/empirical orthogonal function (EOF) analysis to decompose multi‐year time series of glacier speed, combined from three satellite‐derived products at four glaciers feeding Sermilik Fjord, Greenland. This improves on single‐point methods by yielding spatial patterns (EOFs), which ensure the result reflects data at all locations on the glacier, and associated temporal patterns (PCs), which allow identification of glacier type. We find that the leading EOF is uniformly signed over the entire glacier domain, that this mode explains the majority of the variance in speed, and therefore that glacier type can be inferred from the leading PC. We find that Helheim Glacier was terminus‐driven, Fenris Glacier and Midgard Glacier were runoff‐adapting, and Pourquoi Pas Glacier was runoff‐driven over 2016–2021. Our classification agrees with previous work for Helheim and Midgard Glaciers, but differs at the other two. At all but Fenris Glacier, the leading PC correlates significantly with the speed pattern observed at the single point used in previous analyses. Thus, Fenris Glacier has more complex flow patterns than single‐point analysis can capture, and wider spatial analysis techniques such as EOF/PC are required. We suggest that, due to its low computational cost and inclusion in standard analysis packages, EOF/PC analysis should be used for assessing glacier type.

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Section: Discussioncontrasting

confidence: 69%

Section: Introductionmentioning

confidence: 99%

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confidence: 99%

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Seasonal Flow Types of Glaciers in Sermilik Fjord, Greenland, Over 2016–2021

Poinar

2023

JGR Earth Surface

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“…However, in their analyses of Jakobshavn Isbrae, Joughin et al (2012) and Ashmore et al (2022) found that other processes contributes as well but to a smaller degree. For Helheim Glacier in southeast Greenland, Ultee et al (2022) concluded that both terminus position and runoff are important controls on the seasonal variations in flow. This is most likely the case for most glaciers and must be taken into account when interpreting the clusters.…”

Section: Discussionmentioning

confidence: 99%

“…For Helheim Glacier in southeast Greenland, Ultee et al. (2022) concluded that both terminus position and runoff are important controls on the seasonal variations in flow. This is most likely the case for most glaciers and must be taken into account when interpreting the clusters.…”

Section: Discussionmentioning

confidence: 99%

Seasonal Patterns of Greenland Ice Velocity From Sentinel‐1 SAR Data Linked to Runoff

Solgaard

Rapp

Noël

et al. 2022

Geophysical Research Letters

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The Greenland Ice Sheet (GrIS) is losing mass and has been a major contributor to sea-level rise since year 2000 (Fox-Kemper et al., 2021), and the contributions from surface melting and discharge at the marine outlet glaciers contributed equally to the mass loss in the period 1992-2018 (Shepherd et al., 2020). The dynamic response of the marine outlet glaciers to atmospheric and oceanic forcings remains a key uncertainty in determining the future ice-sheet mass-balance and projecting future sea level changes (Bevis et al., 2019;Fox-Kemper et al., 2021;Goelzer et al., 2020;Slater et al., 2020). Fast flowing ice feeds into the marine outlets and carries ice accumulated in the interior to the ocean. The discharge from these marine outlet glaciers have generally increased since the 2000s (Mankoff et al., 2020), and the glaciers further respond to climate on seasonal timescales (Bartholomew

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Effects of topography on dynamics and mass loss of lake-terminating glaciers in southern Patagonia

Minowa

Schaefer

Skvarca³

2023

J. Glaciol.

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Calving glaciers are highly sensitive to bedrock geometry near their terminus. To understand the mechanisms controlling rapid calving glaciers’ mass loss, we measured the lake topography in front of four lake-terminating glaciers in the southern Patagonian icefield. Using remotely sensed surface elevation data, we calculated flotation height and surface slope and compared those with changes in ice-front position, surface speed and surface elevation. Rapid retreat accompanied by rapid flow acceleration and ice surface steepening was observed at Glaciar Upsala from 2008–2011, and at O'Higgins and Viedma glaciers from 2016–present. Surface lowering in the lower part of Glaciar Upsala reached 30 m a−1 and was 18 m a−1 and 12 m a−1 at O'Higgins and Viedma glaciers, respectively. Near- or super-buoyant conditions were observed prior to these events, leading to gradual flow acceleration due to low effective pressure and decoupling from the bed. The super-buoyant condition and gradual acceleration imply full-thickness buoyant calving, which causes the ice front to retreat from the shallow bedrock topography with substantial flow acceleration. We conclude that the buoyancy force plays an important role in the rapid mass loss of lake-terminating glaciers in southern Patagonia.

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Helheim Glacier ice velocity variability responds to runoff and terminus position change at different timescales

Cited by 10 publications

References 101 publications

Seasonal Flow Types of Glaciers in Sermilik Fjord, Greenland, Over 2016–2021

Seasonal Flow Types of Glaciers in Sermilik Fjord, Greenland, Over 2016–2021

Seasonal Patterns of Greenland Ice Velocity From Sentinel‐1 SAR Data Linked to Runoff

Effects of topography on dynamics and mass loss of lake-terminating glaciers in southern Patagonia

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