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Ursula Rick Institute of Arctic and Alpine Research (INSTAAR) University of Colorado Campus Box 450 Boulder, CO 80309-0450 Tel: 303-492-8392 Fax: 303-735-8180 Ursula.Rick@Colorado.edu

Current PhD Research:

Meltwater flow through the Greenland Ice Sheet:
I am studying the flow of meltwater through the percolation facies of the Greenland Ice Sheet. The percolation facies are generally not saturated with meltwater, thus this problem involves unsaturated flow through the snow and firn. In recent years, the melt intensity on the surface of the Greenland Ice Sheet has increased. For the purposes of determining effects on climate and sea level rise, it is important to know the destination of surface melt. Meltwater can travel vertically down into the snow and firn, where it will refreeze in the percolation facies. This would not cause a change in the ice sheet mass balance. The meltwater can also travel downslope out of the percolaction facies and envetually reach the end of the ice sheet. This latter process would result in ice sheet mass loss. Impermeable boundaries in the snow and firn determine, to a large extent, whether meltwater will travel downslope or vertically down into the ice sheet.

To aid in the large scale characterization of the near-surface snow in the percolation facies, space-borne radar remote sensing is utilized. Due to the unique backscatter properties of the percolation facies, radar scatterometry can be used to detect melt features such as ice pipes, ice lenses and other impermeable boundaries. RADARSAT and past synthetic aperture radar (SAR) instruments provide high resolution images of the ice sheet surface. Dry snow will appear grey due to multiple scattering with the snowpack. Wet snow appears very dark due to spectral reflectance off the wet surface of the ice sheet. Finally, dry snow containing melt features will appear bright due to scattering off the dense lenses and pipes. Thus we can use radar to determine where and when melt occurs on the ice sheet and hopefully, how that meltwater travels through the snowpack.

I am working on this project under the direction of Dr. Tad Pfeffer of INSTAAR, Dr. Konrad Steffen of CIRES at the University of Colorado and Dr. Waleed Abdalati of NASA Headquarters and the NASA Goddard Space Flight Center.

Please visit Ursula Rick's homepage at INSTAAR