Arctic Field Projects



Project Title: Collaborative Research: Sonic Logging the NEEM Corehole, Greenland (Award# 1208635)

PI: Waddington, Edwin D (edw@uw.edu)
Phone: (206) 543.4585 
Institute/Department: U of Washington, Department of Earth and Space Sciences 
IPY Project?
Funding Agency: US\Federal\NSF\GEO\OPP\ARC\ANS
Program Manager: Dr. William Wiseman (wwiseman@nsf.gov)
Discipline(s): | Cryosphere\Glaciology | Cryosphere\Icesheet Borehole Science | Cryosphere\Paleoclimate |

Project Web Site(s):
NSF_Award_Info: http://www.nsf.gov/awardsearch/showAward.do?AwardN...

Science Summary:
When NEEM project members drilled through the Greenland ice sheet, reaching bedrock in summer 2011, they collected an ice core containing over 150 meters of ice from the last interglacial period (the Eemian, about 150,000 years ago). As researchers prepare to make a detailed study of this core for past climate information, they need to be able to interpreting the layering and deformation of the ice, which becomes especially difficult, due to crystal orientation (called ice fabric) properties, the deeper in the ice sheet the core is taken. While Crystal-orientation—ice fabric—is random near the surface, it tends to become strongly aligned vertically at depth, as the ice sheet deforms. Yet ice fabric can vary greatly over distances of a few meters as a result of strain history, grain size, and impurity content of the snow, all of which correlate with past climate information. This project’s researchers will use sonic instruments to profile the NEEM ice core hole. They will thus collect detailed information on crystal structure of the ice directly adjacent to the NEEM ice core, an effort that will shed light on flow rate and deformation of the core itself. When combined with thin-section analysis of the ice core, information from these sonic measurements will help researchers make a more precise interpretation of the climate history and ice-sheet flow history contained in the NEEM ice core record. This will, in turn, help scientists provide a more accurate climate history as it is revealed in the core. This work will be the first full-waveform measurement in Greenland, and the first to include dated Eemian ice. The specific goals for this proposal include: 1. Collect full-waveform data in the borehole using sonic logging instruments. 2. Analyze these data for P-wave and S-wave speed and attenuation. 3. Derive a fabric profile from wave speeds and compare with existing thin-section data. 4. Initiate collaborations using the fabric to learn about past ice flow and past climate.

Logistics Summary:
This effort is a collaboration between PIs Waddington (1208635, UW, LEAD) and Pettit (1208806, UAF). After being invited by the NEEM steering committee to participate, the scientists proposed and were awarded a RAPID grant to obtain sonic velocity profiles from the deep borehole at NEEM. They will collect detailed information on crystal structure of the ice directly adjacent to the NEEM ice core, an effort that will shed light on flow rate and deformation of the core itself. When combined with thin-section analysis of the ice core, information from these sonic measurements will help researchers make a more precise interpretation of the climate history and ice-sheet flow history contained in the NEEM ice core record. This will, in turn, help scientists provide a more accurate climate history. Starting in the third week of May, 2012, a field team of two will spend about two weeks at the NEEM field site profiling the NEEM ice core hole. The researchers will travel from the U.S. via the ANG logistics chain from Scotia to Kangerlussuaq and on to NEEM. The original effort involved use of a specialized winch, which was determined to be unavailable during the field work period. The researchers thus devised an alternate plan: the University of Nebraska, Lincoln, will send to Greenland the U.S. logging winch used at South Pole Station for the USAP’s Ice Cube project. The winch will be shipped to Kangerlussuaq via the ANG in mid- May. It will be forwarded to NEEM with the sonic logging team. The U Nebraska winch will be returned to the U.S. via the ANG logistics chain at the end of June. As a back-up option, the team will also make new electrical and mechanical connections for the NEEM drill winch so that the equipment at the drill site can be used for the sonic logging.

CPS will coordinate ANG flights for 2 people and cargo and meal tickets in Kangerlussuaq. All other support (lodging, flights to NEEM, NEEM user days) will be arranged by the University of Copenhagen/ NEEM group. The PI will arrange other support and pay for it with grant funds.
SeasonField SiteDate InDate Out#People
2012Greenland - Kangerlussuaq05 / 20 / 2012 06 / 09 / 20122
2012Greenland - NEEM05 / 24 / 2012 06 / 05 / 20122
 


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