HR: 0800h
AN: C51B-0283    [Abstracts]
TI: Developing a Bubble Number-Density Paleoclimatic Indicator for Glacier Ice
AU: * Spencer, M K
EM: mks125@psu.edu
AF: Penn State University, 517 Deike Bldg., University Park, PA 16802 United States
AU: Alley, R B
EM: ralley@essc.psu.edu
AF: Penn State University, 517 Deike Bldg., University Park, PA 16802 United States
AB: Ice cores provide outstanding records of past climate changes. Confidence in reconstructions is improved by having multiple, independent, physically based indicators. Past allowable accumulation rate/temperature combinations can be estimated from the measured number-density of bubbles in an ice core, using a new technique. Density increase and grain growth in polar firn both are controlled by temperature and accumulation rate, and their integrated effects are recorded in the number-density of bubbles as the firn changes to ice. A physical model of these processes, optimized to fit published data on recently formed bubbles, reconstructs accumulation rates from recent temperatures with a two-sigma uncertainty of only 26%. Bubble number-densities in samples from the Siple Dome, Antarctica, ice core reveal changes in accumulation rate consistent with other paleoclimatic indicators and lead us to conclude that bubble number-densities will be a valuable, and in some cases essential, source of information when reconstructing past climate.
DE: 0724 Ice cores (4932)
DE: 1621 Cryospheric change (0776)
DE: 9310 Antarctica (4207)
SC: Cryosphere [C]
MN: Fall Meeting 2005