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Full-Text Articles in Earth Sciences
Georadar-Derived Estimates Of Firn Density In The Percolation Zone, Western Greenland Ice Sheet, Joel Brown, John Bradford, Joel Harper, W. Tad Pfeffer, Neil Humphrey, Ellen Mosley-Thompson
Georadar-Derived Estimates Of Firn Density In The Percolation Zone, Western Greenland Ice Sheet, Joel Brown, John Bradford, Joel Harper, W. Tad Pfeffer, Neil Humphrey, Ellen Mosley-Thompson
Neil Humphrey
Greater understanding of variations in firn densification is needed to distinguish between dynamic and melt-driven elevation changes on the Greenland ice sheet. This is especially true in Greenland’s percolation zone, where firn density profiles are poorly documented because few ice cores are extracted in regions with surface melt. We used georadar to investigate firn density variations with depth along a ~70 km transect through a portion of the accumulation area in western Greenland that partially melts. We estimated electromagnetic wave velocity by inverting reflection traveltimes picked from common midpoint gathers. We followed a procedure designed to find the simplest velocity …
Air Compression As A Mechanism For The Underdamped Slug Test Response In Fractured Glacier Ice, Toby W. Meierbachtol, Joel T. Harper, Neil F. Humphrey, Jeremy Shaha, John H. Bradford
Air Compression As A Mechanism For The Underdamped Slug Test Response In Fractured Glacier Ice, Toby W. Meierbachtol, Joel T. Harper, Neil F. Humphrey, Jeremy Shaha, John H. Bradford
Neil Humphrey
Artificial perturbations of borehole water levels, known as slug tests, are a useful means of characterizing the glacier hydrologic system. Slug tests were performed on Bench Glacier, Alaska, in 21 boreholes over three field seasons during the transition from a winter to a summer drainage mode. Fifty-four slug tests were conducted, with water level monitoring in up to five boreholes adjacent to the slugged borehole. Seven of the slug tests were performed in conjunction with dye dispersion tests to identify water pathways within the slugged borehole following perturbation. Nearly 60% of monitored adjacent boreholes showed a hydraulic connection to the …