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Summary of Proposal LAN1214

TitleAnalysis of the evolving velocity field at Columbia Glacier, AK, USA
Investigator ONEEL, Shad - U. S. Geological Survey, University of Colorado Boulder, Alaska Science Center
Team Member
Assistant Research P Arendt, Anthony - University of Alaska Fairbanks, Geophysical Institute
Principal Engineer, Joughin, Ian - University of Washington, Earth and Space Sciences, Applied Physics Laboratory, Polar Science Center
Research ONEEL, Shad - United States Geological Survey, University of Colorado Boulder, Alaska Science Center
SummaryAlaska’s Columbia Glacier has been inrapid retreat since the early 1980s, discharging over 150 km3 of iceto the sea. A quantitative ability to understand the recent changes, includingthe dramatic speedups (50 to 100%) and the partitioning of mass losses betweendynamics and increased rates of surface melting, is imperative for predictingnear-future changes in sea level [e.g Pfefferet al, 2008]. Whilehelpful, the international constellation of SAR and optical satellites hasprovided only sparse and sporadic observations of Alaska’s rapidly changing tidewaterglaciers. In most cases image resolution has been insufficient over broadareas, and high-resolution acquisitions have been targeted over small regionsof the larger glaciers. TSX is ideally suited to measuring change on fastmoving glaciers broad spatial coverage at fine resolution and short-repeatintervals. The systematic observations we propose will expand our knowledge ofhow Columbia Glacier is responding to rapid mass loss and reservoir drawdown,both of which are important processes in the sea level budget over the nextcentury. During late2009, Columbia Glacier retreated through a prominent pinning point in thechannel.In large part due to preliminaryTSX acquisitions, we know that a doubling of speed, extending more than 15 kmfrom the calving front, resulted and has been sustained for over a year. Thus,we propose to continue a set of TSX observations that commenced during early2011 to systematically observe and study the continued retreat.These data will be processed to yieldtime-series of glacier velocity, which will be made available to the glaciologyand other science communities. Known basal geometry permits estimation of iceflux, which from Columbia Glacier alone represents approximately 10% of AlaskaGlacier losses [Berthier et al, 2010;Arendt et al, in prep]. Theseacquisitions and the resulting products represent a major TSX contribution tothe long-standing Columbia Glacier project, which extends 30 years, spanningretreat inception to the present-day. These data will also play an integralrole in a study designed to quantitatively characterize runoff and runoffvariability to the Gulf of Alaska (O’Neel Arendt, Hood). We plan to use theColumbia Glacier data as a baseline to estimate calving glacier contributionsover regional scales.

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