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Articles 1 - 6 of 6
Full-Text Articles in Glaciology
Kinetic Grain Growth In Firn Induced By Meltwater Infiltration On The Greenland Ice Sheet, Kirsten Leigh Gehl
Kinetic Grain Growth In Firn Induced By Meltwater Infiltration On The Greenland Ice Sheet, Kirsten Leigh Gehl
Graduate Student Theses, Dissertations, & Professional Papers
The microstructure of polar firn governs its porosity, permeability, and compaction rate, and is therefore important to studies of surface elevation change, heat and gas exchange, and meltwater infiltration on ice sheets. Previous work on high-elevation, dry-firn has identified two distinct atmospheric drivers of kinetic grain growth in deposited snow, but both mechanisms result in near-surface mm-scale layers. In this work, we show that meltwater infiltration through surface wetting fronts and deep preferential flow in the Greenland Ice Sheet (GrIS) percolation zone leads to the formation and preservation of centi- to decimeter scale layers of faceted firn, ranging from faceted …
Depth Distribution Of Liquid Water In Greenlands Firn Layer Based On L-Band Radiometry, A Snow Physics Model, And Machine Learning, Taylor D. Moon
Depth Distribution Of Liquid Water In Greenlands Firn Layer Based On L-Band Radiometry, A Snow Physics Model, And Machine Learning, Taylor D. Moon
Graduate Student Theses, Dissertations, & Professional Papers
The accurate estimation of the amount of meltwater retained by Greenland’s firn layer and its distribution over depth is essential for assessing both the current and future mass balance of the Greenland Ice Sheet. When meltwater infiltrates the firn, it exists as a quantifiable volume of liquid water, measurable as the one-dimensional liquid water amount, hereafter referred to as LWA. A promising new tool for estimating LWA is L-band passive microwave satellite radiometry, which can provide twice-daily estimates using empirical models of firn microwave emission. However, this method faces two primary limitations. First, retrievals are untested against field observations and …
Ice Flow Impacts The Firn Structure Of Greenland's Percolation Zone, Rosemary C. Leone
Ice Flow Impacts The Firn Structure Of Greenland's Percolation Zone, Rosemary C. Leone
Graduate Student Theses, Dissertations, & Professional Papers
One dimensional simulations of firn evolution neglect horizontal transport as the firn column moves down slope during burial. This approach is justifiable near Greenland's ice divide, where ice flow is near vertical, but fidelity is lost in the percolation zone where horizontal ice flow advects the firn column through climate gradients. We simulate firn evolution processes under advection conditions using a transient, thermo-mechanically coupled model for firn densification and heat transfer with various schemes for meltwater penetration and refreezing. The simulations isolate processes in synthetic runs and investigate an ice core site and four transects of Greenland’s percolation zone. 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 …