Abstract
Abstract. We present measurements of crystal c-axis orientations and mean grain area from the Dome Summit South (DSS) ice core drilled on Law Dome, East Antarctica. All measurements were made on location at the borehole site during drilling operations. The data are from 185 individual thin sections obtained between a depth of 117 m below the surface and the bottom of the DSS core at a depth of 1196 m. The median number of c-axis orientations recorded in each thin section was 100, with values ranging from 5 through to 111 orientations. The data from all 185 thin sections are provided in a single comma-separated value (csv) formatted file which contains the c-axis orientations in polar coordinates, depth information for each core section from which the data were obtained, the mean grain area calculated for each thin section and other data related to the drilling site. The data set is also available as a MATLAB™ structure array. Additionally, the c-axis orientation data from each of the 185 thin sections are summarized graphically in figures containing a Schmidt diagram, histogram of c-axis colatitudes and rose plot of c-axis azimuths. All these data are referenced by doi:10.4225/15/5669050CC1B3B and are available free of charge at https://data.antarctica.gov.au.
Highlights
The greatest source of uncertainty in forecasts of sea level rise during the 21st century is the contribution from the Antarctic and Greenland ice sheets (e.g. Willis and Church, 2012; Gregory et al, 2013)
We present measurements of crystal c-axis orientations and mean grain area from the Dome Summit South (DSS) ice core drilled on Law Dome, East Antarctica
Observations of ice microstructures from deep drilled polar ice cores play a vital role in the development and validation of ice flow relations for numerical ice sheet modelling
Summary
The greatest source of uncertainty in forecasts of sea level rise during the 21st century is the contribution from the Antarctic and Greenland ice sheets (e.g. Willis and Church, 2012; Gregory et al, 2013). Lile, 1978; van der Veen and Whillans, 1994; Azuma and Goto-Azuma, 1996; Svendsen and Hutter, 1996; Thorsteinsson, 2002; Gillet-Chaulet et al, 2005; Placidi et al, 2010) In such flow relations the anisotropic viscosity of a polycrystalline aggregate is obtained from the orientation relationship between the grain c-axes and the stress configuration, or some parameterization of these orientation effects. The continued development and validation of physically accurate flow relations for ice sheet modelling requires observations of ice microstructures from deep drilled ice cores, including the patterns of preferred crystal c-axis orientations within an ice mass Such data can be obtained from the analysis of thin section samples. The well-preserved layering at the DSS site, combined with the maritime influence on the orographically driven high accumulation rates on Law Dome has made the DSS ice core a valuable resource for generating mid- and high-latitude palaeoclimate proxy records from the Holocene and Last Glacial Maximum (LGM; van Ommen and Morgan, 2010; Plummer et al, 2012; Vance et al, 2013; Roberts et al, 2015; Vance et al, 2015)
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