Collaborative Research: Combined Physical Property Measurements at Siple Dome

This award supports a two-year collaborative effort to more fully understand the climatic history and physical properties of the Siple Dome, Antarctica deep ice core, to develop a new paleoclimatic technique based on bubble number-density, and to improve the U.S. capability to analyze ice-core physical properties rapidly and accurately. The Siple Dome ice core from West Antarctica is yielding important paleoclimatic insights, but has proven more difficult than some cores to interpret owing to the large iceflow effects on the paleoclimatic record. Paleoclimatic indicators that do not rely on iceflow corrections thus would be of value. The bubble number-density offers one such indicator, because it preserves information on mean temperature and accumulation rate during the transformation of firn to ice. We will focus on thin-section characteristics that are important to ice flow and the interpretation of the ice-core history, such as c-axis fabrics, and will use indicators that we have been developing, such as the correlation between grain elongation and the c-axis orientation, to gain additional information. To achieve this quickly and accurately, and to prepare for future projects, we propose to upgrade the automatic caxis- fabric analyzer that Wilen has built and housed at the National Ice Core Laboratory. The intellectual merit of the proposed activity includes improved estimates of paleoclimatic conditions in an important region, improved understanding of a new paleoclimatic research tool, greater understanding of ice flow and of linkages to physical properties, and a better instrument for further U.S. research in ice-core physical properties at the National Ice Core Laboratory. The broader impacts resulting from the proposed activity include providing better understanding of abrupt climate change and of ice flow, which eventually should help policy-makers, as well as an improved U.S. capability to analyze ice cores. The proposed research will assist the studies of two promising young scientists. Results of the research will be incorporated into courses and public outreach reaching at least hundreds or thousands of people per year.