Collaborative Research: Anisotropy, Abrupt Climate Change, and the Deep Ice in West AntarcticaEntry ID: pettit_0940650
Abstract: This award supports a project to constrain the accumulation rate, thickness, and temperature history for Siple Dome using a vertical velocity profile that includes the effects of an evolving fabric on deformation through time, to invert the depth-profile of fabric determined from sonic velocity measurements and grain size observed in thin sections in Siple Dome for the surface temperature and ... accumulation rate changes in the past, focusing on the apparent abrupt climate change events at 22ka and 15ka.
The fabric dataset provides crystal fabric orientations for several
numerical experiments of fabric evolution. The experiments examine how
differing stress regimes affect variations in crystal fabric. Contained are
netCDF format files of crystal orientations, crystal size, crystal
dislocation densities, stress profiles, and fabric eigenvalues for each
experiment. netCDF is an open-source data format hosted by the University
Corporation for Atmospheric Research (UCAR) and resources are freely
available from their website:http://www.unidata.ucar.edu/software/netcdf/.
This record includes the model's Matlab code, tested on Matlab versions
2009b and 2011a. The code can take run multiple experiments in parallel but
does not require this.
Also included are Matlab codes for generating random distribution of
crystals using either the Watson distribution or the uniform (on the
surface of the unit sphere) distribution. Matlab codes plotting, contouring
Schmidt plots, and calculating fabric area-weighted fabric eigevalues is
Purpose: The intellectual merit of the work is that it will extract past climate information from a number of physical properties of the deep ice using a coupled fabric evolution and ice-sheet flow model. The focus will be on the deep ice-age ice at Siple Dome, where the ice-core record shows puzzling signals and where modeling results imply intriguing deformation patterns. The method will also be applied ... to the records from Byrd Station and Taylor Dome to ultimately form a basis for future analysis of the West Antarctic Divide core. The broader impacts of the project are that it will ultimately contribute to our understanding of the effects of anisotropy on ice flow dynamics in West Antarctica. It will contribute to our understanding of the connection between ice flow and the paleoclimate record in ice cores, particularly with respect to the relationship between the chemical record and ice deformation. And it will contribute a new ice-flow model that includes the effects of anisotropy and fabric evolution.
CRYOSPHERE > GLACIERS/ICE SHEETS
CRYOSPHERE > GLACIERS/ICE SHEETS > ABLATION ZONES/ACCUMULATION ZONES
CRYOSPHERE > GLACIERS/ICE SHEETS > FIRN
CRYOSPHERE > GLACIERS/ICE SHEETS > ICE SHEETS
CRYOSPHERE > SNOW/ICE
CRYOSPHERE > SNOW/ICE > SNOW STRATIGRAPHY
CRYOSPHERE > SNOW/ICE > SNOW/ICE TEMPERATURE
PALEOCLIMATE > ICE CORE RECORDS
ISO Topic Category
Data Set Progress
Phone: (907) 474-5389
Email: pettit at gi.alaska.edu
Department of Geology and Geophysics University of Alaska Fairbanks 900 Yukon Dr. Rm 308
Province or State: Alaska
Postal Code: 99775
Kennedy, J.H; Pettit, E.C. DiPrinzio, C. in review."The evolution of ice crystal fabric in ice sheets and its link to climate history" Journal of Glaciology.
Pettit, E; Waddington, E; Harrison, W; Thorsteinsson, T; Elsberg, D; Morack, J; and Zumberge, M. "The crossover stress, anisotropy, and the flow law at Siple Dome, West Antarctica," Journal of Glaciology, v.57(201), 2011, p. 39.
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Creation and Review Dates
DIF Creation Date: 2012-09-04
Last DIF Revision Date: 2012-09-12