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| Titel |
Testing the integrity of stable isotope records of two Spitsbergen ice cores by using high-resolution tritium data. |
| VerfasserIn |
L. G. van der Wel, H. A. J. Meijer, E. Isaksson, M. M. Helsen, R. S. W. van de Wal, T. Martma, V. A. Pohjola, J. C. Moore |
| Konferenz |
EGU General Assembly 2009
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| Medientyp |
Artikel
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| Sprache |
Englisch
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| Digitales Dokument |
PDF |
| Erschienen |
In: GRA - Volume 11 (2009) |
| Datensatznummer |
250027473
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| Zusammenfassung |
| The ratios of 1H16O2H and 1H18O1H in precipitation water vary with temperature and can
therefore be used as a proxy for past climate. Ever since the 1960-s, retrieving these isotope
signals has been the main motivation for the drilling of deep ice cores. Most of the ice core
records originate from selected sites in Greenland and Antarctica. Other Arctic
locations are much less used. However, since the late 1990-s ice cores have been
drilled on the Lomonosovfonna and Holtedahlfonna ice caps in Spitsbergen. The
advantages of drilling at these sites lies in the high accumulation rate present in
Spitsbergen, as well as the very location of the Spitsbergen archipelago. However,
due to relatively high temperatures in this region, the isotope record is affected by
melt and subsequent percolation, thereby potentially losing its value for climatic
studies.
In an attempt to test the integrity of the Spitsbergen cores, we measured the concentration
of the radioactive isotope of hydrogen (tritium) at high spatial (and thus temporal) resolution.
Due to above-ground nuclear bomb tests in the 1950-s and 1960-s, the tritium signal in the
atmosphere has been highly variable in that period, with distinct peaks. Moreover, due to the
high load of tritium in the stratosphere at that time, spring and early summer mixing between
stratosphere and troposphere induced a clear seasonal pattern in precipitation records for two
decades.
The tritium concentration in precipitation has been measured (monthly average) since the
1950-s. After precipitation the tritium record is altered due to decay, diffusion and melt.
Incorporating information of these three processes into a numerical model, we produce a
quantitative estimate how much the isotope record is influenced by melt and percolation. This
gives us a tool to determine whether the stable isotope record is a valid proxy for past
temperatures. |
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