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| Titel |
Long-range memory in internal and forced dynamics of millennium-long climate model simulations |
| VerfasserIn |
L. Østvand, T. Nilsen, K. Rypdal, D. Divine, M. Rypdal |
| Medientyp |
Artikel
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| Sprache |
Englisch
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| ISSN |
2190-4979
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| Digitales Dokument |
URL |
| Erschienen |
In: Earth System Dynamics ; 5, no. 2 ; Nr. 5, no. 2 (2014-08-27), S.295-308 |
| Datensatznummer |
250115366
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| Publikation (Nr.) |
 copernicus.org/esd-5-295-2014.pdf |
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| Zusammenfassung |
| Northern Hemisphere (NH) temperature records from a palaeoclimate reconstruction and a number of
millennium-long climate model experiments are investigated for long-range memory (LRM). The
models are two Earth system models and two atmosphere–ocean general circulation models. The
periodogram, detrended fluctuation analysis and wavelet variance analysis are applied to examine
scaling properties and to estimate a scaling exponent of the temperature records. A simple
linear model for the climate response to external forcing is also applied to the reconstruction
and the forced climate model runs, and then compared to unforced control runs to extract the LRM
generated by internal dynamics of the climate system. The climate models show strong persistent
scaling with power spectral densities of the form S(f) ~ f −β with 0.8 < β < 1 on
timescales from years to several centuries. This is somewhat stronger persistence than found
in the reconstruction (β ≈ 0.7). We find no indication that LRM found in these model
runs is induced by external forcing, which suggests that LRM on sub-decadal to century time
scales in NH mean temperatures is a property of the internal dynamics of the climate system.
Reconstructed and instrumental sea surface temperature records for a local site, Reykjanes Ridge,
are also studied, showing that strong persistence is found also for local ocean temperature. |
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