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| Titel |
Modeling dust emission response to North Atlantic millennial-scale climate variations from the perspective of East European MIS 3 loess deposits |
| VerfasserIn |
A. Sima, M. Kageyama, D.-D. Rousseau, G. Ramstein, Y. Balkanski, P. Antoine, C. Hatté |
| 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. 4 ; Nr. 9, no. 4 (2013-07-03), S.1385-1402 |
| Datensatznummer |
250018081
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| Publikation (Nr.) |
 copernicus.org/cp-9-1385-2013.pdf |
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| Zusammenfassung |
| European loess sequences of the Marine Isotope Stage 3 (~60–25 kyr BP)
show periods of strong dust accumulation alternating with
episodes of reduced sedimentation, favoring soil development. In the western
part of the loess belt centered around 50° N, these variations
appear to have been related to the North Atlantic rapid climate changes: the
Dansgaard–Oeschger (DO) and Heinrich (H) events. It has been recently
suggested that the North Atlantic climate signal can be detected further
east, in loess deposits from Stayky (50°05.65' N,
30°53.92' E), Ukraine. Here we use climate and dust emission modeling to
investigate this data interpretation. We focus on the areas north and
northeast of the Carpathians, where loess deposits can be found, and the
corresponding main dust sources must have been located as well. The
simulations were performed with the LMDZ atmospheric general circulation
model and the ORCHIDEE land surface model. They represent a reference
"Greenland stadial" state and two perturbations, seen as sensitivity tests
with respect to changes in the North Atlantic surface conditions between
30° and 63° N: a "Greenland interstadial" and an "H event".
The main source for the loess deposits in the studied area is identified as
a dust deflation band, with two very active spots located west-northwest
from our reference site. Emissions only occur between February and June.
Differences from one deflation spot to another, and from one climate state
to another, are explained by analyzing the relevant meteorological and
surface variables. Over most of the source region, the annual emission
fluxes in the "interstadial" experiment are 30 to 50% lower than the
"stadial" values; they would only be about 20% lower if the inhibition
of dust uplift by the vegetation were not taken into account. Assuming that
lower emissions result in reduced dust deposition leads us to the conclusion
that the loess–paleosol stratigraphic succession in the Stayky area reflects
indeed North Atlantic millennial variations. In the main deflation areas of
Western Europe, the vegetation effect alone determined most of the
(~50% on average) stadial–interstadial flux differences.
Even if its impact in Eastern Europe is less pronounced, this effect remains
a key factor in modulating aeolian emissions at the millennial timescale.
Conditions favorable to initiating particularly strong dust storms within a
few hundred kilometers upwind from our reference site, simulated in the
month of April of the H event experiment, support the correlation of H
events with peaks in grain size index in some very detailed loess profiles,
indicating increased coarse sedimentation. |
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