Spatial and temporal distributions of surface mass balance between Concordia and Vostok stations, Antarctica, from combined radar and ice core data: first results and detailed error analysis
Results from ground-penetrating radar (GPR) measurements and shallow ice cores carried out during a scientific traverse between Dome Concordia (DC) and Vostok stations are presented in order to infer both spatial and temporal characteristics of snow accumulation over the East Antarctic Plateau....
Main Authors: | , , , , , , , |
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Format: | Article |
Language: | English |
Published: |
Copernicus Publications
2018-05-01
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Series: | The Cryosphere |
Online Access: | https://www.the-cryosphere.net/12/1831/2018/tc-12-1831-2018.pdf |
Summary: | Results from ground-penetrating radar (GPR) measurements and shallow ice
cores carried out during a scientific traverse between Dome Concordia (DC)
and Vostok stations are presented in order to infer both spatial and temporal
characteristics of snow accumulation over the East Antarctic Plateau.
Spatially continuous accumulation rates along the traverse are computed from
the identification of three equally spaced radar reflections spanning about
the last 600 years. Accurate dating of these internal reflection horizons
(IRHs) is obtained from a depth–age relationship derived from volcanic
horizons and bomb testing fallouts on a DC ice core and shows a very good
consistency when tested against extra ice cores drilled along the radar
profile. Accumulation rates are then inferred by accounting for density
profiles down to each IRH. For the latter purpose, a careful error analysis
showed that using a single and more accurate density profile along a DC core
provided more reliable results than trying to include the potential spatial
variability in density from extra (but less accurate) ice cores distributed
along the profile.
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The most striking feature is an accumulation pattern that remains constant
through time with persistent gradients such as a marked decrease from
26 mm w.e. yr<sup>−1</sup> at DC to 20 mm w.e. yr<sup>−1</sup> at the
south-west end of the profile over the last 234 years on average (with a similar
decrease from 25 to 19 mm w.e. yr<sup>−1</sup> over the last 592 years).
As for the time dependency, despite an overall consistency with similar
measurements carried out along the main East Antarctic divides, interpreting
possible trends remains difficult. Indeed, error bars in our measurements are
still too large to unambiguously infer an apparent time increase in
accumulation rate.
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For the proposed absolute values, maximum margins of error are in the range
4 mm w.e. yr<sup>−1</sup> (last 234 years) to 2 mm w.e. yr<sup>−1</sup> (last
592 years), a decrease with depth mainly resulting from the time-averaging
when computing accumulation rates. |
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ISSN: | 1994-0416 1994-0424 |