The middle Pleistocene transition as a generic bifurcation on a slow manifold
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| 024 | 7 | 0 | |a 10.1007/s00382-015-2501-9 |2 doi |
| 035 | |a (NATIONALLICENCE)springer-10.1007/s00382-015-2501-9 | ||
| 245 | 0 | 4 | |a The middle Pleistocene transition as a generic bifurcation on a slow manifold |h [Elektronische Daten] |c [Peter Ashwin, Peter Ditlevsen] |
| 520 | 3 | |a The Quaternary period has been characterised by a cyclical series of glaciations, which are attributed to the change in the insolation (incoming solar radiation) from changes in the Earth's orbit around the Sun. The spectral power in the climate record is very different from that of the orbital forcing: prior to 1000kyr before present most of the spectral power is in the 41kyr band while since then the power has been in the 100kyr band. The change defines the middle Pleistocene transition (MPT). The MPT does not indicate any noticeable difference in the orbital forcing. The climate response to the insolation is thus far from linear, and appears to be structurally different before and after the MPT. This paper presents a low order conceptual model for the oscillatory dynamics of the ice sheets in terms of a relaxation oscillator with multiple levels subject to the Milankovitch forcing. The model exhibits smooth transitions between three different climate states; an interglacial (i), a mild glacial (g) and a deep glacial (G) as proposed by Paillard (Nature 391:378-381, 1998). The model suggests a dynamical explanation in terms of the structure of a slow manifold for the observed allowed and "forbidden” transitions between the three climate states. With the model, the pacing of the climate oscillations by the astronomical forcing is through the mechanism of phase-resetting of relaxation oscillations in which the internal phase of the oscillation is affected by the forcing. In spite of its simplicity as a forced ODE, the model is able to reproduce not only general features but also many of the details of oscillations observed in the climate record. A particular novelty is that it includes a slow drift in the form of the slow manifold that reproduces the observed dynamical change at the MPT. We explain this change in terms of a transcritical bifurcation in the fast dynamics on varying the slow variable; this bifurcation can induce a sudden change in periodicity and amplitude of the cycle and we suggest that this is associated with a branch of "canard oscillations” that appear for a small range of parameters. The model is remarkably robust at simulating the climate record before, during and after the MPT. Even though the conceptual model does not point to specific mechanisms, the physical implication is that the major reorganisation of the climate response to the orbital forcing does not necessarily imply that there was a big change in the environmental conditions. | |
| 540 | |a Springer-Verlag Berlin Heidelberg, 2015 | ||
| 690 | 7 | |a Middle Pleistocene transition |2 nationallicence | |
| 690 | 7 | |a Nonlinear oscillation |2 nationallicence | |
| 690 | 7 | |a Ice age |2 nationallicence | |
| 690 | 7 | |a Slow manifold |2 nationallicence | |
| 690 | 7 | |a Bifurcation |2 nationallicence | |
| 700 | 1 | |a Ashwin |D Peter |u Centre for Systems, Dynamics and Control, Harrison Building, University of Exeter, EX4 4QF, Exeter, UK |4 aut | |
| 700 | 1 | |a Ditlevsen |D Peter |u Centre for Ice and Climate, Niels Bohr Institute, Juliane Maries Vej 30, 2100, Copenhagen, Denmark |4 aut | |
| 773 | 0 | |t Climate Dynamics |d Springer Berlin Heidelberg |g 45/9-10(2015-11-01), 2683-2695 |x 0930-7575 |q 45:9-10<2683 |1 2015 |2 45 |o 382 | |
| 856 | 4 | 0 | |u https://doi.org/10.1007/s00382-015-2501-9 |q text/html |z Onlinezugriff via DOI |
| 898 | |a BK010053 |b XK010053 |c XK010000 | ||
| 900 | 7 | |a Metadata rights reserved |b Springer special CC-BY-NC licence |2 nationallicence | |
| 908 | |D 1 |a research-article |2 jats | ||
| 949 | |B NATIONALLICENCE |F NATIONALLICENCE |b NL-springer | ||
| 950 | |B NATIONALLICENCE |P 856 |E 40 |u https://doi.org/10.1007/s00382-015-2501-9 |q text/html |z Onlinezugriff via DOI | ||
| 950 | |B NATIONALLICENCE |P 700 |E 1- |a Ashwin |D Peter |u Centre for Systems, Dynamics and Control, Harrison Building, University of Exeter, EX4 4QF, Exeter, UK |4 aut | ||
| 950 | |B NATIONALLICENCE |P 700 |E 1- |a Ditlevsen |D Peter |u Centre for Ice and Climate, Niels Bohr Institute, Juliane Maries Vej 30, 2100, Copenhagen, Denmark |4 aut | ||
| 950 | |B NATIONALLICENCE |P 773 |E 0- |t Climate Dynamics |d Springer Berlin Heidelberg |g 45/9-10(2015-11-01), 2683-2695 |x 0930-7575 |q 45:9-10<2683 |1 2015 |2 45 |o 382 | ||