Journal cover Journal topic
Earth System Dynamics An interactive open-access journal of the European Geosciences Union
Journal topic

Journal metrics

Journal metrics

  • IF value: 4.351 IF 4.351
  • IF 5-year value: 5.124 IF 5-year
    5.124
  • CiteScore value: 4.44 CiteScore
    4.44
  • SNIP value: 1.250 SNIP 1.250
  • IPP value: 4.10 IPP 4.10
  • SJR value: 2.203 SJR 2.203
  • Scimago H <br class='hide-on-tablet hide-on-mobile'>index value: 29 Scimago H
    index 29
  • h5-index value: 31 h5-index 31
Volume 5, issue 2
Earth Syst. Dynam., 5, 295-308, 2014
https://doi.org/10.5194/esd-5-295-2014
© Author(s) 2014. This work is distributed under
the Creative Commons Attribution 3.0 License.
Earth Syst. Dynam., 5, 295-308, 2014
https://doi.org/10.5194/esd-5-295-2014
© Author(s) 2014. This work is distributed under
the Creative Commons Attribution 3.0 License.

Research article 27 Aug 2014

Research article | 27 Aug 2014

Long-range memory in internal and forced dynamics of millennium-long climate model simulations

L. Østvand1, T. Nilsen2, K. Rypdal2, D. Divine3, and M. Rypdal2 L. Østvand et al.
  • 1Department of Physics and Technology, UiT The Arctic University of Norway, Tromsø, Norway
  • 2Department of Mathematics and Statistics, UiT The Arctic University of Norway, Tromsø, Norway
  • 3Norwegian Polar Institute, Tromsø, Norway

Abstract. 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.

Publications Copernicus
Download
Citation
Share