Modelling debris transport within glaciers by advection in a full-Stokes ice flow model

Wirbel, Anna; Jarosch, Alexander H.; Nicholson, Lindsey

doi:10.5194/tc-12-189-2018

Cited by 31 publications

(39 citation statements)

References 49 publications

(73 reference statements)

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“…Our results show that debris‐covered tongues can be generally characterized as flatter and located at lower elevations than debris‐free tongues. Moreover, the avalanche contributing area correlates strongly with the percentage of debris cover, hinting that large part of the debris supply originates from the glacier upper reaches (e.g., Wirbel et al, ). These conclusions are in line with those of Scherler et al (), even though, contrary to them, we do not include ice surface velocity in our analysis.…”

Section: Discussionmentioning

confidence: 98%

Heterogeneous Influence of Glacier Morphology on the Mass Balance Variability in High Mountain Asia

et al. 2019

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We investigate the control of the morphological variables on the 2000–2016 glacier‐wide mass balances of 6,470 individual glaciers of High Mountain Asia. We separate the data set into 12 regions assumed to be climatically homogeneous. We find that the slope of the glacier tongue, mean glacier elevation, percentage of supraglacial debris cover, and avalanche contributing area all together explain a maximum of 48% and a minimum of 8% of the glacier‐wide mass balance variability, within a given region. The best predictors of the glacier‐wide mass balance are the slope of the glacier tongue and the mean glacier elevation for most regions, with the notable exception of the inner Tibetan Plateau. Glacier‐wide mass balances do not differ significantly between debris‐free and debris‐covered glaciers in 7 of the 12 regions analyzed. Lake‐terminating glaciers have more negative mass balances than the regional averages, the influence of lakes being stronger on small glaciers than on large glaciers.

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Section: Discussionmentioning

confidence: 98%

Heterogeneous Influence of Glacier Morphology on the Mass Balance Variability in High Mountain Asia

et al. 2019

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“…The pronounced effect of debris should therefore not be ignored in numerical experiments to determine the future evolution of mountain glaciers, yet only few studies have included this complex process in time-dependent models (e.g. Jouvet et al, 2011;Rowan et al, 2015;Huss and Fischer, 2016;Kienholz et al, 2017;Rezepkin and Popovnin, 2018;Wirbel et al, 2018).…”

Section: Introductionmentioning

confidence: 99%

Modelling the evolution of Djankuat Glacier, North Caucasus, from 1752 until 2100 CE

et al. 2020

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Abstract. We use a numerical flow line model to simulate the behaviour of the Djankuat Glacier, a World Glacier Monitoring Service reference glacier situated in the North Caucasus (Republic of Kabardino-Balkaria, Russian Federation), in response to past, present and future climate conditions (1752–2100 CE). The model consists of a coupled ice flow–mass balance model that also takes into account the evolution of a supraglacial debris cover. After simulation of the past retreat by applying a dynamic calibration procedure, the model was forced with data for the future period under different scenarios regarding temperature, precipitation and debris input. The main results show that the glacier length and surface area have decreased by ca. 1.4 km (ca. −29.5 %) and ca. 1.6 km2 (−35.2 %) respectively between the initial state in 1752 CE and present-day conditions. Some minor stabilization and/or readvancements of the glacier have occurred, but the general trend shows an almost continuous retreat since the 1850s. Future projections using CMIP5 temperature and precipitation data exhibit a further decline of the glacier. Under constant present-day climate conditions, its length and surface area will further shrink by ca. 30 % by 2100 CE. However, even under the most extreme RCP 8.5 scenario, the glacier will not have disappeared completely by the end of the modelling period. The presence of an increasingly widespread supraglacial debris cover is shown to significantly delay glacier retreat, depending on the interaction between the prevailing climatic conditions, the debris input location, the debris mass flux magnitude and the time of release of debris sources from the surrounding topography.

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“…The debris currently found at the glacier's centreline has either moved there by secondary processes such as glacier movement and on-glacier sliding, or originated from other sources, e.g. headwall erosion (Benn and Owen, 2002) or basal debris, (re-)emerging at the glacier surface towards the tongue (Boulton, 1978;Wirbel et al, 2018).…”

Section: Debris Distribution Onto the Glaciermentioning

confidence: 99%

Estimating lateral moraine sediment supply to a debris-covered glacier in the Himalaya

Woerkom

Steiner

Kraaijenbrink

et al. 2018

Preprint

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Abstract. Debris-covered glacier tongues in the Himalaya play an important role in the high-altitude water cycle. The thickness of the debris layer is a key control of the melt rate of those tongues, yet little is known about the relative importance of the three potential sources of debris supply to those glaciers: the headwalls, the glacier bed or the lateral moraines. In this study we hypothesize that erosion from the lateral moraines is a significant debris supply to the debris-covered tongues, in particular when the tongue is disconnected from the headwall due to glacier downwasting. To test this hypothesis eight high-resolution and highly accurate digital elevation models for the lateral moraines of the debris-covered Lirung glacier in Nepal derived from an unmanned aerial vehicle between May 2013 and April 2018 are used. The analysis shows that the lateral moraines erode at an average rate of 0.31 ± 0.26 m yr−1 during this period driven by different erosion processes. There is also a higher erosion rate observed in the monsoon season (0.42 m yr−1) than in the dry season (0.25 m yr−1). In addition the loose lower parts of the lateral moraines erode at a faster rate during both seasons. These erosion rates translate into an annual increase in debris thickness ranging from 0.17 m yr−1 when the eroded material is distributed over the entire glacier to 0.29 m yr−1 in case the material is deposited in a narrow runout zone. It is concluded that the lateral moraines provide an important source of surface debris for glaciers in an advanced state of mass loss, and the source needs to be incorporated into models of glacier evolution. Further research should focus on how large this negative feedback is in controlling the melt of the tongues and a better understanding of the redistribution of debris on the tongue is therefore required.

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Modelling debris transport within glaciers by advection in a full-Stokes ice flow model

Cited by 31 publications

References 49 publications

Heterogeneous Influence of Glacier Morphology on the Mass Balance Variability in High Mountain Asia

Heterogeneous Influence of Glacier Morphology on the Mass Balance Variability in High Mountain Asia

Modelling the evolution of Djankuat Glacier, North Caucasus, from 1752 until 2100 CE

Estimating lateral moraine sediment supply to a debris-covered glacier in the Himalaya

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