Regional climate signal vs. local noise: a two-dimensional view of water isotopes in Antarctic firn at Kohnen Station, Dronning Maud Land
In low-accumulation regions, the reliability of <i>δ</i><sup>18</sup>O-derived temperature signals from ice cores within the Holocene is unclear, primarily due to the small climate changes relative to the intrinsic noise of the isotopic signal. In order to learn about the rep...
| Main Authors: | , , , , |
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| Format: | Article |
| Language: | English |
| Published: |
Copernicus Publications
2016-07-01
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| Series: | Climate of the Past |
| Online Access: | http://www.clim-past.net/12/1565/2016/cp-12-1565-2016.pdf |
| Summary: | In low-accumulation regions, the reliability of
<i>δ</i><sup>18</sup>O-derived temperature signals from ice cores within
the Holocene is unclear, primarily due to the small climate changes relative
to the intrinsic noise of the isotopic signal. In order to learn about the
representativity of single ice cores and to optimise future ice-core-based
climate reconstructions, we studied the stable-water isotope composition of
firn at Kohnen Station, Dronning Maud Land, Antarctica. Analysing
<i>δ</i><sup>18</sup>O in two 50 m long snow trenches allowed us
to create an unprecedented, two-dimensional image characterising the isotopic
variations from the centimetre to the 100-metre scale. Our results show
seasonal layering of the isotopic composition but also high horizontal
isotopic variability caused by local stratigraphic noise. Based on the
horizontal and vertical structure of the isotopic variations, we derive
a statistical noise model which successfully explains the trench data. The
model further allows one to determine an upper bound for the reliability of
climate reconstructions conducted in our study region at seasonal to annual
resolution, depending on the number and the spacing of the cores taken. |
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| ISSN: | 1814-9324 1814-9332 |