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| Titel |
To what extent can global warming events influence scaling properties of climatic fluctuations in glacial periods? |
| VerfasserIn |
Tommaso Alberti, Fabio Lepreti, Antonio Vecchio, Vincenzo Carbone |
| Konferenz |
EGU General Assembly 2017
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| Medientyp |
Artikel
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| Sprache |
en
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| Digitales Dokument |
PDF |
| Erschienen |
In: GRA - Volume 19 (2017) |
| Datensatznummer |
250148644
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| Publikation (Nr.) |
 EGU/EGU2017-12919.pdf |
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| Zusammenfassung |
| The Earth’s climate is an extremely unstable complex system consisting of nonlinear and still
rather unknown interactions among atmosphere, land surface, ice and oceans. The system is
mainly driven by solar irradiance, even if internal components as volcanic eruptions and
human activities affect the atmospheric composition thus acting as a driver for climate
changes. Since the extreme climate variability is the result of a set of phenomena operating
from daily to multi-millennial timescales, with different correlation times, a study of the
scaling properties of the system can evidence non-trivial persistent structures, internal or
external physical processes.
Recently, the scaling properties of the paleoclimate changes have been analyzed by
distinguish between interglacial and glacial climates [Shao and Ditlevsen, 2016]. The results
show that the last glacial record (20-120 kyr BP) presents some elements of multifractality,
while the last interglacial period (0-10 kyr BP), say the Holocene period, seems to
be characterized by a mono-fractal structure. This is associated to the absence of
Dansgaard-Oeschger (DO) events in the interglacial climate that could be the cause for the
absence of multifractality. This hypothesis is supported by the analysis of the period between
18 and 27 kyr BP, i.e. during the Last Glacial Period, in which a single DO event have been
registred.
Through the Empirical Mode Decomposition (EMD) we were able to detect a timescale
separation within the Last Glacial Period (20-120 kyr BP) in two main components: a
high-frequency component, related to the occurrence of DO events, and a low-frequency one,
associated to the cooling/warming phase switch [Alberti et al., 2014]. Here, we investigate
the scaling properties of the climate fluctuations within the Last Glacial Period, where
abrupt climate changes, characterized by fast increase of temperature usually called
Dansgaard-Oeschger (DO) events, have been particularly pronounced. By using the
MultiFractal Detrended Fluctuation Analysis (MF-DFA), we show that a multifractal
structure exists for both high- and low-frequency fluctuations in Northern and Southern
hemispheres, with different scaling exponents, thus indicating a long-range persistence of the
climatic variability within the whole Last Glacial Period. Our results evidence that both
DO events and cooling/warming cycles must be considered as processes of the
internal component of the Earth’s climate, rather than processes related to external
forcings. This study should be helpful for investigation of the internal origin of climate
changes.
References
Shao, Z.G. and Ditlevsen, P.D., Nature Commun., 7, 10951, (2016).
Alberti, T., Lepreti, F., Vecchio, A., Bevacqua, E., Capparelli, V. and Carbone,
V., Clim. Past, 10, 1751 (2014). |
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