Morphology and evolution of supraglacial hummocks on debris‐covered Himalayan glaciers

Bartlett, Oliver T.; Ng, Felix; Rowan, Ann V.

doi:10.1002/esp.5043

Cited by 16 publications

(24 citation statements)

References 63 publications

Supporting

Mentioning

Contrasting

Order By: Relevance

“…Even so, some of the patterns observed here can help to inform interpretations of process-landform relationships. The length-scales used in the domain set-up (∼10 2 m) are generally consistent with those observed in topographic features of modern debris-covered valley glaciers (Bartlett et al, 2020), and for simulations that produced significant postglacial relief, moraine ridges are similarly spaced. This spacing is also consistent with some observed hummocky moraine tracts (albeit in only one dimension) (Johnson and Clayton, 2005), and is inherited from the prescribed spacing of debris source nonuniformity.…”

Section: Discussionsupporting

confidence: 61%

Numerical Simulation of Supraglacial Debris Mobility: Implications for Ablation and Landform Genesis

Moore

2021

Front. Earth Sci.

View full text Add to dashboard Cite

Supraglacial debris does not remain fixed atop ablating ice, but can move across the ice surface as supraglacial topography evolves. This active debris movement (distinct from passive movement due to underlying ice motion) affects landform genesis as well as the rate and spatial distribution of ablation. While observations of debris transport across evolving supraglacial topography are abundant, models of these coupled processes over timescales of decades and longer are few. Here I adapt a numerical model of coupled ablation and downslope debris transport to simulate the evolution of an idealized debris-covered glacier on the timescale of complete de-icing. The model includes ablation that depends on supraglacial debris thickness and a hillslope-scale debris transport function that scales non-linearly with slope angle. Ice thickness and debris distribution evolve with model time, allowing complete simulation of de-icing and landform construction in an idealized glacier test-section. The model produces supraglacial relief that leads to topographic inversions consistent with conceptual models of hummocky landform genesis. Model results indicate that the relief of the glacier surface and postglacial hummocks depend on the relationship between characteristic timescales for ablation and debris transport, which is defined as an index of debris mobility. When debris mobility is high, topographic inversions are rapid and supraglacial and postglacial relief are subdued. When debris mobility is low, more pronounced supraglacial relief is produced, but postglacial relief remains subdued. An intermediate mobility appears to optimize both postglacial relief and the rate of de-icingcompared with both highly-mobile and immobile debris. This enhancement of de-icing due to debris mobility could contribute to the observed anomalous rates of ablation in some debris-covered glaciers.

show abstract

Section: Discussionsupporting

confidence: 61%

Numerical Simulation of Supraglacial Debris Mobility: Implications for Ablation and Landform Genesis

Moore

2021

Front. Earth Sci.

View full text Add to dashboard Cite

show abstract

“…The final stage of cliff reburial occurred during our study interval as the cliff exhausted the available topography, as suggested in Brun and others (2016). It is apparent, however, that the reworking of the debris surface by the cliff's backwasting led to thinner debris over a broad area (Bartlett and others, 2020). We note that the melt distance of the area occupied by the ice cliff in May was 3–3.6 m, whereas the peak melt distances (>4.5 m) occurred in an area not observed to be occupied by an ice cliff, and melt distances within the scallop area (>3 m) were twice the value of the surrounding area (1–1.9 m).…”

Section: Resultsmentioning

confidence: 99%

Quantifying heterogeneous monsoonal melt on a debris-covered glacier in Nepal Himalaya using repeat uncrewed aerial system (UAS) photogrammetry

et al. 2021

View full text Add to dashboard Cite

The ablation zones of debris-covered glaciers in Himalaya exhibit heterogeneous processes and melt patterns. Although sub-debris melt is measured at ablation stakes, the high variability of debris thickness necessitates distributed melt measurements at the glacier scale. Focusing on Annapurna III Glacier, we used uncrewed aerial system (UAS) photogrammetry to estimate total volume loss and slope-perpendicular glacier melt between May and November 2019 using flow-corrected point clouds. Results indicated the average elevation change was −1.10 ± 0.19 m, while the mean melt was −0.87 m w.e., equating to a mean melt rate of −0.47 cm w.e. d−1. However, the spatial pattern was highly variable due to complex local processes necessitating future study over short intervals. The evaluation of specific areas showed the interplay of debris thickness variability, subseasonal debris redistribution, supraglacial channel reconfiguration and the imprint of relict ice cliffs in leading to contemporary melt rates. Ice cliffs had higher melt distances (mean −3.9 ± 0.19 m) compared to non-cliff areas (mean −0.75 ± 0.19 m) and were the predominant control on the spatial patterns of seasonal melt rates. Crucially, the definition of ice cliff areas from thinning data has a profound impact on derived melt rates and melt enhancement. Our study demonstrates the possibility and utility of deriving fully-distributed slope-perpendicular melt measurements.

show abstract

“…

Debris-covered glaciers are widespread in all mountain ranges around the globe (Herreid & Pellicciotti, 2020b;Scherler et al, 2018) and especially in High Mountain Asia (HMA), where half of the glaciers larger than 2 km 2 have more than 5% of their total area covered by a layer of rock debris (Herreid & Pellicciotti, 2020b) varying in thickness from centimeter to meter scale. These glaciers are often characterized by undulating, hummocky topography (Bartlett et al, 2020) and their surface is punctuated by supraglacial ponds, streams, and ice cliffs. Ice cliffs have been observed in all the main mountain ranges of the planet (

…”

mentioning

confidence: 99%

Interannual Dynamics of Ice Cliff Populations on Debris‐Covered Glaciers From Remote Sensing Observations and Stochastic Modeling

et al. 2021

View full text Add to dashboard Cite

Debris-covered glaciers are widespread in all mountain ranges around the globe (Herreid & Pellicciotti, 2020b;Scherler et al., 2018) and especially in High Mountain Asia (HMA), where half of the glaciers larger than 2 km 2 have more than 5% of their total area covered by a layer of rock debris (Herreid & Pellicciotti, 2020b) varying in thickness from centimeter to meter scale. These glaciers are often characterized by undulating, hummocky topography (Bartlett et al., 2020) and their surface is punctuated by supraglacial ponds, streams, and ice cliffs. Ice cliffs have been observed in all the main mountain ranges of the planet (

show abstract

Morphology and evolution of supraglacial hummocks on debris‐covered Himalayan glaciers

Cited by 16 publications

References 63 publications

Numerical Simulation of Supraglacial Debris Mobility: Implications for Ablation and Landform Genesis

Numerical Simulation of Supraglacial Debris Mobility: Implications for Ablation and Landform Genesis

Quantifying heterogeneous monsoonal melt on a debris-covered glacier in Nepal Himalaya using repeat uncrewed aerial system (UAS) photogrammetry

Interannual Dynamics of Ice Cliff Populations on Debris‐Covered Glaciers From Remote Sensing Observations and Stochastic Modeling

Contact Info

Product

Resources

About