Terminus dynamics at an advancing glacier: Taku Glacier, Alaska

Truffer, Martin; Motyka, R. J.; Hekkers, M.; Howat, I. M.; King, Matt

doi:10.3189/002214309790794887

Cited by 27 publications

(41 citation statements)

References 28 publications

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“…1 for glacier locations). Margerie, Johns Hopkins, and Taku Glacier are some of the few currently advancing tidewater glaciers in Alaska (e.g., Motyka and Echelmeyer, 2003;Truffer et al, 2009;McNabb and Hock, 2014), while Rendu Glacier has been previously identified as a surge-type glacier (Field, 1969). The pattern of elevation change shown on Rendu Glacier in Fig.…”

Section: Uncertaintiesmentioning

confidence: 92%

Sensitivity of glacier volume change estimation to DEM void interpolation

et al. 2019

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Glacier mass balance has been estimated on individual glacier and regional scales using repeat digital elevation models (DEMs). DEMs often have gaps in coverage ("voids"), the properties of which depend on the nature of the sensor used and the surface being measured. The way that these voids are accounted for has a direct impact on the estimate of geodetic glacier mass balance, though a systematic comparison of different proposed methods has been heretofore lacking. In this study, we determine the impact and sensitivity of void interpolation methods on estimates of volume change. Using two spatially complete, high-resolution DEMs over southeast Alaska, USA, we artificially generate voids in one of the DEMs using correlation values derived from photogrammetric processing of Advanced Spaceborne Thermal Emission and Reflection Radiometer (ASTER) scenes. We then compare 11 different void interpolation methods on a glacier-by-glacier and regional basis. We find that a few methods introduce biases of up to 20 % in the regional results, while other methods give results very close ( < 1 % difference) to the true, non-voided volume change estimates. By comparing results from a few of the best-performing methods, an estimate of the uncertainty introduced by interpolating voids can be obtained. Finally, by increasing the number of voids, we show that with these best-performing methods, reliable estimates of glacier-wide volume change can be obtained, even with sparse DEM coverage.Published by Copernicus Publications on behalf of the European Geosciences Union.

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Section: Uncertaintiesmentioning

confidence: 92%

Sensitivity of glacier volume change estimation to DEM void interpolation

et al. 2019

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“…As a result of global warming, the number of glaciers in Greenland that currently have floating termini has rapidly diminished; most are now grounded [ Enderlin and Howat , ]. In Alaska, surface ablation rates at tidewater glaciers can exceed 10 m yr −1 [e.g., Truffer et al , ] and these coastal glaciers receive significant liquid precipitation at lower elevations during the warm season. Both meltwater and rain ultimately exit the glacier as subglacial discharge (Figure ).…”

Section: Morphologies Of Glacier Termini In Various Settingsmentioning

confidence: 99%

Where glaciers meet water: Subaqueous melt and its relevance to glaciers in various settings

Truffer

Motyka

2016

Reviews of Geophysics

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Glacier change is ubiquitous, but the fastest and largest magnitude changes occur in glaciers that terminate in water. This includes the most rapidly retreating glaciers, and also several advancing ones, often in similar regional climate settings. Furthermore, water-terminating glaciers show a large range in morphology, particularly when ice flow into ocean water is compared to that into freshwater lakes. All water-terminating glaciers share the ability to lose significant volume of ice at the front, either through mechanical calving or direct melt from the water in contact. Here we present a review of the subaqueous melt process. We discuss the relevant physics and show how different physical settings can lead to different glacial responses. We find that subaqueous melt can be an important trigger for glacier change. It can explain many of the morphological differences, such as the existence or absence of floating tongues. Subaqueous melting is influenced by glacial runoff, which is largely a function of atmospheric conditions. This shows a tight connection between atmosphere, oceans and lakes, and glaciers. Subaqueous melt rates, even if shown to be large, should always be discussed in the context of ice supply to the glacier front to assess its overall relevance. We find that melt is often relevant to explain seasonal evolution, can be instrumental in shifting a glacier into a different dynamical regime, and often forms a large part of a glacier's mass loss. On the other hand, in some cases, melt is a small component of mass loss and does not significantly affect glacier response.

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“…This is in part because the only "marine-terminating" glacier on the Juneau Icefield, Taku, has developed a terminal moraine through excavation of proglacial sediments that prevents it from calving (e.g., Criscitiello et al, 2010). The lack of calving and high AAR (Accumulation Area Ratio-the fraction of the glacier that is in the accumulation zone) of Taku Glacier both contribute to mass gain and advance there (e.g., Larsen et al, 2007;Pelto et al, 2008;Truffer et al, 2009;Criscitiello et al, 2010;Melkonian et al, 2014;Larsen et al, 2015). Thus, Taku is another example of a marine-terminating glacier that has a disproportionately large effect on the total mass balance an icefield, just like the four large outlet glaciers at Stikine.…”

Section: Thinning At Marine Vs Land-terminating Glaciersmentioning

confidence: 99%

Stikine Icefield Mass Loss between 2000 and 2013/2014

Melkonian¹,

Willis

Pritchard

2016

Front. Earth Sci.

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We calculate thinning rates ( dh ) at the 5800 km 2 Stikine Icefield of southeast dt Alaska from stacked digital elevation models (DEMs) acquired between 2000 and 2013/2014, and glacier velocities between 1985 and 2014 from feature tracking on optical image pairs. We find a mass change rate of −3.3 ± 1.1 Gt yr −1 between 2000 and 2014, equivalent to an area-averaged elevation change rate of −0.57 ± 0.18 m w.e. yr −1 . In 2014, land-terminating glaciers are 50% of the Stikine Icefield's glaciated area and contribute −0.9 ± 0.4 Gt yr −1 of mass change (27% of the total), while marine-terminating glaciers are only 30% of the total glaciated area, but contribute 1.5−1 − ± 0.3 Gt yr (or 45% of total mass change, with the remaining mass loss from lacustrine-terminating glaciers). We estimate the frontal ablation flux between 2000 and 2014 at the four largest marine-terminating glaciers on the Stikine Icefield (covering 90-95% of the marine-terminating glaciated area) using our glacier velocities and maps of fjord bathymetry to estimate terminus cross sections and glacier thicknesses. The combined 2014 frontal ablation flux of these four glaciers is 1.18 ± 0.14 Gt yr −1 , which may account for the difference in average mass loss between marine-and land-terminating glaciers on the Stikine Icefield. The Stikine and adjacent Juneau Icefields have very different mass loss contributions from marine-terminating glaciers (45% vs. effectively 0%), but both have area-averaged elevation change rates that are less negative than Alaska-wide estimates, which is surprising for these southernmost icefields in Alaska.

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Terminus dynamics at an advancing glacier: Taku Glacier, Alaska

Cited by 27 publications

References 28 publications

Sensitivity of glacier volume change estimation to DEM void interpolation

Sensitivity of glacier volume change estimation to DEM void interpolation

Where glaciers meet water: Subaqueous melt and its relevance to glaciers in various settings

Stikine Icefield Mass Loss between 2000 and 2013/2014

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