Crevasses are important hydrologic conduits that evacuate surface melt water from the ice sheet, impacting glacier dynamics and contributing to global sea level rise. This thesis describes a novel processing pipeline for retrieving likely crevasse locations from ICESat waveform returns, and demonstrates the methodology over a large land terminating drainage basin of the southwest Greenland ice sheet. This method is then extended and applied to the ice sheet periphery, and validated against optical imagery derived crevasse observations. The dataset described herein provides the earliest (years 2004 - 2006) baseline assessment of crevasse occurrence throughout the Greenland ice sheet periphery, and is a crucial comparison point for the ICESat-2 mission in assessing decadal length changes over the region. I find robust evidence of crevassing 135km inland at heights above 1800 meters, with weaker indications of surface anomalies occurring even higher on the ice sheet (up to 2300 meters). In addition, I provide both climatological (melt, runoff, surface mass balance), and mechanistic (strain, temperature, slope, thickness) parameter space distributions of crevassed areas. The distribution of crevasses suggests that in a warming climate, the ice sheet will have the potential to route water to englacial hydrologic systems at much higher elevations than previously thought, and could indicate significant ice sheet vulnerability in increasingly intense melt years. The spatial distribution of crevasses are highly coincident with ice lenses, and possibly exclusive of firn aquifers– a finding that could inform the distribution of crevasses through a range of climatological warming scenarios.
|Commitee:||Serreze, Mark, Colgan, William, Rajaram, Hari, Thayer, Jeff, Farmer, Carson|
|School:||University of Colorado at Boulder|
|School Location:||United States -- Colorado|
|Source:||DAI-B 81/3(E), Dissertation Abstracts International|
|Keywords:||Crevasses, Glaciology, Greenland, Laser waveform, Machine learning|
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