Preprints
https://doi.org/10.5194/cp-2021-126
https://doi.org/10.5194/cp-2021-126

  01 Nov 2021

01 Nov 2021

Review status: this preprint is currently under review for the journal CP.

Milankovic Pseudo-cycles Recorded in Sediments and Ice Cores Extracted by Singular Spectrum Analysis

Fernando Lopes1, Pierpaolo Zuddas2, Vincent Courtillot1, Jean-Louis Le Mouël1, Jean-Baptiste Boulé3, Alexis Maineult2, and Marc Gèze4 Fernando Lopes et al.
  • 1Institut de Physique du Globe, Paris University, Paris 75005, France
  • 2Sorbonne Université, CNRS, EPHE, UMR 7619 METIS, 75005 Paris, France
  • 3Genome Structure and Instability Laboratory, CNRS UMR 7196, INSERM U1154, Muséum national d’Histoire naturelle, Alliance Sorbonne Université, 75005 Paris, France
  • 4Centre de Microscopie et d’Imagerie Numérique, Muséum National d’Histoire Naturelle, Paris, France, Muséum national d’Histoire naturelle, Alliance Sorbonne Université, 75005 Paris, France

Abstract. Milankovic cycles describe the changes in the Earth's orbit and rotation axis and their impact on its climate over thousands of years. Singular Spectrum Analysis (SSA) is a signal processing method that is best known for its ability to find and extract pseudo-cycles in complex signals. In this short paper, we propose to apply it to three time series that have been proposed as geological reference time scales, in order to retrieve, compare and identify their Milankovic periodicities: (1) LR04, a stack of Plio-Pleistocene benthic microfossil records (Lisiecki and Raymo, 2005), (2) the CO2 and CH4 records from the Vostok ice core (Petit et al, 1999) and (3) the long-term orbital solution La04 for the insolation of Laskar et al (2004). The Vostok CO2 and CH4 series share the first 7 SSA components, three main ones (98, 104, 39 kyr), and four smaller ones (18, 22, 65, 180 kyr). CO2 displays a component at 28 kyr and a doublet at 61 and 62 kyr. CH4 displays a doublet near 50 kyr. 18/22 ky is a precession doublet, 62 kyr an insolation component, and 95/105 kyr an insolation/eccentricity doublet. The 49/50 kyr doublet in CH4 is not found in the orbital model. The SSA results for the La04 orbital solution are in excellent agreement with the values obtained by Laskar et al (2004). Four SSA components of obliquity are almost identical (rounded figures are 41, 54, 29 and 39 kyr). As far as eccentricity is concerned, the first five components are 404, 95, 124, 99, and 132 kyr. The next components are not found in our list of components for eccentricity, but they are in the SSA of insolation, at 2338, 970, 488 and 684 kyr. With more than 20 components, the LR04 stack is the richest series. In order of decreasing amplitude, one encounters 41, 95 and 75 kyr components. Next are smaller 39.5 and 53.6 kyr components, and a 22.4 kyr component. One recognizes one of the two main precession components, the doublet of obliquity components, a line at 47.4 kyr that is not found in any of the other spectra, and a doublet at 53.6 and 55.7 kyr, corresponding to the line at 54 kyr found in all four orbital quantities. Next comes a line at 63.6 kyr that may correspond to a line in insolation, CH4 and CO2. Then come components from eccentricity variations at 75.2, 94.5, 107.2, 132.1, 198.6 and 400.9 kyr. The remaining components of LR04 show up in La04. The “elusive ~200 kyr eccentricity cycle” of Hilgen et al (2020) is actually present in all three series, in the La04 orbital model as a 195 ± 6 kyr component of eccentricity and in LR04 as a 198.6 ± 5.6 kyr component. Finding not only the main expected Milankovic periodicities but also many “secondary” components with much smaller amplitudes gives confidence in our iterative SSA method (iSSA), on the quality of the La04 model and on the remarkable LR04 sedimentary stack, with more than 15 “ Milankovic periods”.

Fernando Lopes et al.

Status: open (until 27 Dec 2021)

Comment types: AC – author | RC – referee | CC – community | EC – editor | CEC – chief editor | : Report abuse

Fernando Lopes et al.

Fernando Lopes et al.

Viewed

Total article views: 418 (including HTML, PDF, and XML)
HTML PDF XML Total BibTeX EndNote
329 83 6 418 2 2
  • HTML: 329
  • PDF: 83
  • XML: 6
  • Total: 418
  • BibTeX: 2
  • EndNote: 2
Views and downloads (calculated since 01 Nov 2021)
Cumulative views and downloads (calculated since 01 Nov 2021)

Viewed (geographical distribution)

Total article views: 401 (including HTML, PDF, and XML) Thereof 401 with geography defined and 0 with unknown origin.
Country # Views %
  • 1
1
 
 
 
 
Latest update: 27 Nov 2021
Download
Short summary
We apply Singular Spectrum Analysis (extracts pseudo-cycles in complex signals) to series used in building geological reference time scales, e.g. a benthic microfossil stack and an orbital solution for insolation. SSA of the stack contains not only the main expected Milankovic periods but also a rich collection of “secondary” periods. This validates at the same time our iterative SSA method, the orbital model and the remarkable benthic stack, with more than 15 “ Milankovic periods”.