END OF SEASON FIELD REPORTS

2006-07 End of Season Field Reports


Spatial Variability in Firn Properties from Borehole Optical Stratigraphy at the Inland WAIS Core Site (I-171)
NSF-OPP supported
PI: Edwin Waddington (University of Washington)

Field Team:
Ben Smith (UW)
Jessica Drees (UW)

Season Objectives:
1) Survey an array of boreholes with an optical logging instrument
2) Survey the borehole array with ground penetrating radar
3) Collect two shallow cores for density and grain size measurements

Season Overview:
We (Smith and Drees) arrived in McMurdo November 13. Our flight to WAIS Divide was originally scheduled for November 19, but weather and Herc availability forced a delay until November 21. The weather at WAIS Divide was initially poor, with continual 10 - 20 knot winds and blowing snow. We began by logging four holes drilled and capped in the 2005-6 field season, which allowed us to practice our field techniques without the risk of blowing snow collecting in our computers.

We drilled our first hole to 20 m, on November 25. We were favorably impressed with the ease of use and simplicity of the Sidewinder system. However, because of the large number of holes we were planning, and because Smith was recovering from a broken arm and had difficulty handling the drill stem at depths greater than 16-18 m, we decided to limit later holes to 16 m.

Until the end of November, we continued to drill additional holes while logging holes from previous seasons. At this point, the weather improved markedly, and for the first time we were able to operate our logging equipment without setting up a tent to protect our computers from blowing snow. From this point on we were able to log each hole after 15 minutes or less set-up time, and worked to catch up logging previously drilled holes.

The break in weather also allowed us to begin ground-penetrating radar surveys over our boreholes. Continued cold temperatures required that we build enclosures over the radar antennas to keep them warm with hot water bottles. Early indications are that the accumulation rate varies by around 2% in the area upstream of the main WAIS Divide borehole, on spatial scales of 2-3 km.

On December 8, Steve Profaizer, a reporter with the Antarctic Sun, came with us to log two holes and to drill another. His account of the field experience, plus photos, is available at http://www.waisdivide.unh.edu/Reference/Download.pm/261/Document. We collected core for collaborators on 12/11, during which a videographer from USAP filmed our drilling operations.

On December 12, we drilled our last hole. We left camp 12/14 on a cold-deck flight. We had drilled and logged 14 holes, a total of more than 230 m. We collected samples from two firn pits and collected two short cores to share with collaborators in the US.

Acknowledgements:
We would like to thank Bella Bergeron and Mike Jayred for drilling advice, and Joe Souney for core-handling instructions. Ben Partan and the WAIS Divide camp crew ran a great operation, and took care of us in high style. Julie Palais provided critical support throughout. Bob Hawley originally designed the hole logging equipment, and Ken Taylor, Mary Albert and Tom Neumann all gave essential scientific advice.