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| Titel |
Temperature variations in Greenland from 10 to 110 kyr b2k derived from the NGRIP ice core |
| VerfasserIn |
Philippe Kindler, Markus Leuenberger, Amaëlle Landais, Myriam Guillevic |
| Konferenz |
EGU General Assembly 2013
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| Medientyp |
Artikel
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| Sprache |
Englisch
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| Digitales Dokument |
PDF |
| Erschienen |
In: GRA - Volume 15 (2013) |
| Datensatznummer |
250075654
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| Zusammenfassung |
| During the last ice age dramatic temperature variations of up to 16 °C took place in
Greenland which are now known as Dansgaard-Oeschger-events (DO-events). They most
probably originate from the North Atlantic oceanic and atmospheric circulation system and
are characterised by an abrupt warming within decades followed by a gradual cooling over
hundreds to thousands of years. We have determined local temperature variations for
DO-event 1 to 25 in Greenland based on δ15N measurements from the NorthGRIP ice core,
corresponding to the period from 10 to 110 kyr b2k. The record is a composite of
measurements from two laboratories, Laboratoire des Sciences du Climat et de
l’Environnement, Paris (DO 18 to 25) and the Climate and Environmental Physics Division of
the Physics Institute of the University of Bern (DO 1 to 17) with new measurements from the
beginning of the Holocene to DO 8. Temperature variations were reconstructed by
reproducing the measured 15N/14N ratio of air enclosed in ice bubbles by the firn
densification and heat diffusion model from Schwander. The reconstruction show
temperature amplitudes for the DO-events ranging from 5 to 16 °C, thereby the
corresponding rates of change can exceed 0.5 °C/decade. In order get an agreement between
measured δ15N, Δdepth and Δage values with their modelled analogues, a lower
accumulation rate than the one associated with the used ss09sea06bm1 time scale had to be
assumed. We had to reduce the accumulation rate time dependently by 0 to nearly 40%
with a mean reduction over the whole time period of 16%. With these adjustments
both the Δdepth and the Δage values agree between model and measurements. |
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