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Full-Text Articles in Glaciology
Using Airborne Ku-Band Altimeter Waveforms To Investigate Winter Accumulation And Glacier Facies On Austfonna, Svalbard, Robert L. Hawley, Ola Brandt, Thorben Dunse, Jon Ove Hagen, Veit Helm, Jack Kohler, Kirsty Langley, Eirik Malnes, Kjell-Arild Hogda
Using Airborne Ku-Band Altimeter Waveforms To Investigate Winter Accumulation And Glacier Facies On Austfonna, Svalbard, Robert L. Hawley, Ola Brandt, Thorben Dunse, Jon Ove Hagen, Veit Helm, Jack Kohler, Kirsty Langley, Eirik Malnes, Kjell-Arild Hogda
Dartmouth Scholarship
Winter balance is an important metric for assessing the change on glaciers and ice caps, yet measuring it using ground-based techniques can be challenging. We use the European Space Agency prototype Airborne SAR/Interferometric Radar Altimeter System (ASIRAS) to extract snow depths from the received altimeter waveforms over Austfonna ice cap, Svalbard. Additionally, we attempt to distinguish the long-term firn area from other glacier facies. We validate our results using snow depth and glacier facies characterizations determined from ground-based radar profiles, snow pits and a multi-look satellite synthetic aperture radar image. We show that the depth of the winter snowpack can …
Melt Regimes, Stratigraphy, Flow Dynamics And Glaciochemistry Of Three Glaciers In The Alaska Range, Seth Campbell, Karl Kreutz, Erich Osterberg, Steven Arcone
Melt Regimes, Stratigraphy, Flow Dynamics And Glaciochemistry Of Three Glaciers In The Alaska Range, Seth Campbell, Karl Kreutz, Erich Osterberg, Steven Arcone
Dartmouth Scholarship
We used ground-penetrating radar (GPR), GPS and glaciochemistry to evaluate melt regimes and ice depths, important variables for mass-balance and ice-volume studies, of Upper Yentna Glacier, Upper Kahiltna Glacier and the Mount Hunter ice divide, Alaska. We show the wet, percolation and dry snow zones located below 2700ma.s.l., at 2700 to 3900ma.s.l. and above 3900ma.s.l., respectively. We successfully imaged glacier ice depths upwards of 480m using 40–100MHz GPR frequencies. This depth is nearly double previous depth measurements reached using mid-frequency GPR systems on temperate glaciers. Few Holocene-length climate records are available in Alaska, hence we also assess stratigraphy and flow …
Glacimarine Sedimentation Processes At Kronebreen And Kongsvegen, Svalbard, Laura M. Kehrl, Robert L. Hawley, Ross D. Powell, Julie Brigham-Grette
Glacimarine Sedimentation Processes At Kronebreen And Kongsvegen, Svalbard, Laura M. Kehrl, Robert L. Hawley, Ross D. Powell, Julie Brigham-Grette
Dartmouth Scholarship
Tidewater glaciers deposit sediment at their terminus, thereby reducing the relative water depth. Reduced water depth can lead to increased glacier stability through decreased rates of iceberg calving, glacier thinning and submarine melting. Here we investigate sedimentation processes at the termini of Kronebreen and Kongsvegen, Svalbard. We mapped the fjord floor bathymetry in August 2009 and calculate sedimentation rates based on our bathymetry and that from a similar study in 2005. A grounding-line fan is developing near the current position of the subglacial stream. An older, abandoned grounding-line fan that likely formed between ~1987 and 2001 is degrading near the …
Microstructural Evolution Of Fine-Grained Layers Through The Firn Column At Summit, Greenland, R. Lomonaco, M. Albert, I. Baker
Microstructural Evolution Of Fine-Grained Layers Through The Firn Column At Summit, Greenland, R. Lomonaco, M. Albert, I. Baker
Dartmouth Scholarship
We present a microstructural characterization of fine-grained layers from the top 90 m of firn from Summit, Greenland, performed using a combination of scanning electron microscopy techniques including secondary electron imaging, energy-dispersive spectroscopy and electron backscattered patterns, and X-ray microcomputed tomography. The impurities in the firn, both soluble impurities and dust particles, were found largely in the grain interiors. Both c- and a-axis pole figures do not show strong evidence of a preferred orientation of the grains even at the bottom of the firn column. The firn structure became increasingly anisotropic with vertical alignment in the top 3 m, probably …
Ice Layers As An Indicator Of Summer Warmth And Atmospheric Blocking In Alaska, Eric P. Kelsey, Cameron P. Wake, Karl Kreutz, Erich Osterberg
Ice Layers As An Indicator Of Summer Warmth And Atmospheric Blocking In Alaska, Eric P. Kelsey, Cameron P. Wake, Karl Kreutz, Erich Osterberg
Dartmouth Scholarship
No abstract provided.
A New Technique For Firn Grain-Size Measurement Using Sem Image Analysis, N.E. Spaulding, D.A. Meese, I. Baker, P.A. Mayewski
A New Technique For Firn Grain-Size Measurement Using Sem Image Analysis, N.E. Spaulding, D.A. Meese, I. Baker, P.A. Mayewski
Dartmouth Scholarship
Firn microstructure is accurately characterized using images obtained from scanning electron microscopy (SEM). Visibly etched grain boundaries within images are used to create a skeleton outline of the microstructure. A pixel-counting utility is applied to the outline to determine grain area. Firn grain sizes calculated using the technique described here are compared to those calculated using the techniques of Gow (1969) and Gay and Weiss (1999) on samples of the same material, and are found to be substantially smaller. The differences in grain size between the techniques are attributed to sampling deficiencies (e.g. the inclusion of pore filler in the …
Using Electron Backscatter Diffraction Patterns To Examine Recrystallization In Polar Ice Sheets, Rachel Obbard, Ian Baker, Katherine Sieg
Using Electron Backscatter Diffraction Patterns To Examine Recrystallization In Polar Ice Sheets, Rachel Obbard, Ian Baker, Katherine Sieg
Dartmouth Scholarship
The fabric of polycrystalline ice is typically described using the c-axis orientation alone, but this is insufficient for a full description of grain orientations in this hexagonal material. Electron backscatter diffraction (EBSD) provides full c- and a-axis orientation of individual grains, and is used here to study Greenland Ice Sheet Project 2 (GISP2) ice specimens from depths of 1551, 1642 and 1745 m. Complete orientation data are used to compare nearest-neighbor relationships to overall fabric and to differentiate between recrystallization mechanisms. Changes in orientation between grains and subgrains in GISP2 specimens were correlated with the appearance of grain boundaries on …