Characterizing Differing Modes of Supraglacial Lake Drainage Events along the Western Margin of the Greenland Ice Sheet using GPS,
Passive Seismic, and MODIS Satellite Data
Open Access
Author:
Justin, Randy Michael
Graduate Program:
Geosciences
Degree:
Master of Science
Document Type:
Master Thesis
Date of Defense:
August 24, 2012
Committee Members:
Sridhar Anadakrishnan, Thesis Advisor/Co-Advisor Richard B Alley, Thesis Advisor/Co-Advisor Derrick Lampkin, Thesis Advisor/Co-Advisor
Keywords:
Greenland Ice sheet seismic microseismic GPS MODIS glaciology glacial supra-glacial lake supraglacial lake
Abstract:
Fast-draining supraglacial lakes along the ablation zone of the Greenland Ice Sheet (GrIS) have been the focus of extensive scientific research, chiefly on their role in routing large volumes of surface melt water to the ice sheet base, thus facilitating basal sliding, and creating a mechanism for accelerated ice flow to rapidly affect climate. Though causative relationships exist between surface meltwater fluctuations, enhanced basal sliding, and summer GrIS velocity cycles, their long–term impact on GrIS flow dynamics in a warming climate is not yet well understood. Here we present direct observations of two drainage events from a Greenlandic supraglacial lake that exhibited a different mode of drainage in the 2009 and 2010 Arctic summers. We use GPS, passive seismic, and Moderate- Resolution Imaging Spectroradiometer (MODIS) satellite data to identify and to characterize a rapid lake drainage event in 2009 and a gradual lake drainage event in 2010. We compare ice motion resulting from drainage events, and perform a suite of seismic analyses to investigate the microseismic activity coincident with the rapid drainage event in 2009. In addition, we provide an estimate of microseismic epicenters. We find that the results of this survey reinforce the interpretation of others that the englacial and subglacial hydrology system along the western margin of the GrIS is transitioning from that of an ice sheet to one that resembles a polythermal or temperate (mountain) glacier.
