| NSF Org: |
OPP Office of Polar Programs (OPP) |
| Recipient: |
|
| Initial Amendment Date: | September 21, 2010 |
| Latest Amendment Date: | July 6, 2012 |
| Award Number: | 0948247 |
| Award Instrument: | Continuing Grant |
| Program Manager: |
Julie Palais
OPP Office of Polar Programs (OPP) GEO Directorate for Geosciences |
| Start Date: | October 1, 2010 |
| End Date: | September 30, 2015 (Estimated) |
| Total Intended Award Amount: | $459,161.00 |
| Total Awarded Amount to Date: | $459,161.00 |
| Funds Obligated to Date: |
FY 2011 = $180,990.00 FY 2012 = $63,835.00 |
| History of Investigator: |
|
| Recipient Sponsored Research Office: |
2145 N TANANA LOOP FAIRBANKS AK US 99775-0001 (907)474-7301 |
| Sponsor Congressional District: |
|
| Primary Place of Performance: |
2145 N TANANA LOOP FAIRBANKS AK US 99775-0001 |
| Primary Place of
Performance Congressional District: |
|
| Unique Entity Identifier (UEI): |
|
| Parent UEI: |
|
| NSF Program(s): | ANT Glaciology |
| Primary Program Source: |
|
| Program Reference Code(s): |
|
| Program Element Code(s): |
|
| Award Agency Code: | 4900 |
| Fund Agency Code: | 4900 |
| Assistance Listing Number(s): | 47.078 |
ABSTRACT
Pettit/0948247
This award supports a project to study of the relationship between fabric and climate for the ice near the EPICA Dome C ice core site, East Antarctica. The work builds on an ongoing study at Siple Dome, West Antarctica and takes advantage of collaborations with European scientists and access to the Dome C borehole to make measurements of sonic velocity. The intellectual merit of the project is that a better understanding of how fabric preserves past climate information can improve models of the ice flow near ice core sites and the interpreta-tion of ice core data (particularly paleo-accumulation), and it may allow us to extract climate information directly from fabric data. In addition, because ice deformation is sensitive to the orientation of crystals, ice flow patterns are sensitive to the fabric. Thus, variations in the fabric between glacial and interglacial ice can affect how ice deforms and how fabric in the ice sheet develops. The Dome C site is particularly important for answering these questions, because the ice core shows evidence of eight glacial cycles, not just one as found at Siple Dome or the Greenland sites. The research will improve the understanding of the proxy relationship between sonic-velocity data and fabric; will help to model the pattern of ice flow caused by the fabric variation between glacial and interglacial time periods using these data, existing ice core chemistry and existing and new thin section data, improved surface strain data, and borehole deformation data; and will help to better understand the positive feedback mechanism that enhances fabric (and corresponding rheological) variability through a focused study of several climate transitions and the associated fabric changes. Borehole compressional-wave sonic-velocity will be measured which will complement the sonic-velocity data that already exist for boreholes in Greenland and West Antarctica. These will be the first sonic-velocity measurements in East Antarctica and the first measurements that extend for more than a single glacial/interglacial transition. The project will ultimately contribute to better interpretation of ice core records for both paleoclimate studies and for ice flow history, both of which connect to the broader questions of the role of ice in the climate system. This project will also strengthen the international collaborations within the paleoclimate and ice sheet modeling communities. This project will partially support a graduate student at the University of Alaska Fairbanks who is currently working on modeling ice including anisotropy and it will support the growth of a young scientist through a Post-Doc position. This Post Doc will gain important experience collaborating with the EPICA scientists in studying the climate-fabric relationship. Erin Pettit is active in field-science education for high school students, under-graduates, teachers, and adults. This project will help support the continued development and enhancement of Girls on Ice a program that encourages young women to explore science and the natural world.
PUBLICATIONS PRODUCED AS A RESULT OF THIS RESEARCH
Note:
When clicking on a Digital Object Identifier (DOI) number, you will be taken to an external
site maintained by the publisher. Some full text articles may not yet be available without a
charge during the embargo (administrative interval).
Some links on this page may take you to non-federal websites. Their policies may differ from
this site.
PROJECT OUTCOMES REPORT
Disclaimer
This Project Outcomes Report for the General Public is displayed verbatim as submitted by the Principal Investigator (PI) for this award. Any opinions, findings, and conclusions or recommendations expressed in this Report are those of the PI and do not necessarily reflect the views of the National Science Foundation; NSF has not approved or endorsed its content.
Introduction
Dome C (75oS and 123oW) is the site of an ice core that was drilled by the European Project for Ice Coring in Antarctica (EPICA). This core records over 800,000 years of climate history – the longest record we have yet recovered. Our work contributes to the interpretation of deformation history and accumulation-rate history of the surrounding ice. Of particular interest, the core contains eight glacial-interglacial cycles. These layers of ice from different ice ages and interglacials behave differently, with “softer” ice sandwiched between “stiffer” ice. This sandwiching of layers of different properties means that whole ice sheet will flow differently depending on the layers, perhaps even causing folding and disturbance of layers downstream. The goal of our project is to understand the link between the climate history and this layered softness or stiffness of the ice. We can do this through measuring the speed of sound in the ice.
The value of sonic logging and fabric studies
The specific goal of our project was to measure the velocity of sound through ice, which tells us about the effective viscosity of the ice (the viscosity is the measure of the softness, or fluidity). Each ice crystal has a layered structure – similar to a deck of cards. And it is much easier to shear an ice crystal along the molecular layers than to deform it any other way. Because of the 'slipperiness' of shearing along the laye...
Please report errors in award information by writing to: awardsearch@nsf.gov.
