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| Titel |
Impact of precipitation intermittency on NAO-temperature signals in proxy records |
| VerfasserIn |
M. Casado, P. Ortega, V. Masson-Delmotte, C. Risi, D. Swingedouw, V. Daux, D. Genty, F. Maignan, O. Solomina, B. Vinther, N. Viovy, P. Yiou |
| Medientyp |
Artikel
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| Sprache |
Englisch
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| ISSN |
1814-9324
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| Digitales Dokument |
URL |
| Erschienen |
In: Climate of the Past ; 9, no. 2 ; Nr. 9, no. 2 (2013-03-27), S.871-886 |
| Datensatznummer |
250018025
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| Publikation (Nr.) |
 copernicus.org/cp-9-871-2013.pdf |
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| Zusammenfassung |
| In mid and high latitudes, the stable isotope ratio in precipitation is
driven by changes in temperature, which control atmospheric distillation.
This relationship forms the basis for many continental paleoclimatic
reconstructions using direct (e.g. ice cores) or indirect (e.g. tree ring
cellulose, speleothem calcite) archives of past precipitation. However, the
archiving process is inherently biased by intermittency of precipitation.
Here, we use two sets of atmospheric reanalyses (NCEP (National Centers for Environmental Prediction) and ERA-interim) to
quantify this precipitation intermittency bias, by comparing seasonal
(winter and summer) temperatures estimated with and without precipitation
weighting. We show that this bias reaches up to 10 °C and has
large interannual variability. We then assess the impact of precipitation
intermittency on the strength and stability of temporal correlations between
seasonal temperatures and the North Atlantic Oscillation (NAO).
Precipitation weighting reduces the correlation between winter NAO and
temperature in some areas (e.g. Québec, South-East USA, East Greenland,
East Siberia, Mediterranean sector) but does not alter the main patterns of
correlation. The correlations between NAO, δ18O in
precipitation, temperature and precipitation weighted temperature are
investigated using outputs of an atmospheric general circulation model
enabled with stable isotopes and nudged using reanalyses (LMDZiso (Laboratoire de Météorologie Dynamique Zoom)). In
winter, LMDZiso shows similar correlation values between the NAO and both
the precipitation weighted temperature and δ18O in
precipitation, thus suggesting limited impacts of moisture origin.
Correlations of comparable magnitude are obtained for the available
observational evidence (GNIP (Global Network of Isotopes in Precipitation) and Greenland ice core data). Our findings
support the use of archives of past δ18O for NAO
reconstructions. |
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