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  • 1
    Monograph available for loan
    Monograph available for loan
    Berlin [u.a.] : Springer
    Associated volumes
    Call number: PIK M 490-08-0258 ; PIK M 490-08-0259
    In: Springer series in synergetics
    Description / Table of Contents: Contents: 1. Introduction; 2. Basic Models; 3. Synchronization Due to External Periodic Forcing; 4. Synchronization of Two Coupled Systems; 5. Ensembles of Phase Oscillators; 6. Chains of Coupled Limit-Cycle Oscillators; 7. Ensembles of Chaotic Oscillators with a Periodic-Doubling Route to Chaos, R¨ossler Oscillators; 8. Intermittent-Like Oscillations in Chains of Coupled Maps; 9. Regular and Chaotic Phase Synchronization of Coupled Circle Maps; 10. Controlling Phase Synchronizationin Oscillatory Networks; 11. Chains of Limit-Cycle Oscillators; 12. Chains and Lattices of Excitable Luo-Rudy Systems; 13. Noise-Induced Synchronization in Ensembles of Oscillatory and Excitable Systems; 14. Networks with Complex Topology; Glossary; Ackowledgment; References; Index
    Type of Medium: Monograph available for loan
    Pages: XIV, 368 S. : graph. Darst.
    ISBN: 9783540712688
    Series Statement: Springer series in synergetics
    Branch Library: PIK Library
    Branch Library: PIK Library
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  • 2
    Call number: AWI G6-18-91956
    Description / Table of Contents: Earth's climate varies continuously across space and time, but humankind has witnessed only a small snapshot of its entire history, and instrumentally documented it for a mere 200 years. Our knowledge of past climate changes is therefore almost exclusively based on indirect proxy data, i.e. on indicators which are sensitive to changes in climatic variables and stored in environmental archives. Extracting the data from these archives allows retrieval of the information from earlier times. Obtaining accurate proxy information is a key means to test model predictions of the past climate, and only after such validation can the models be used to reliably forecast future changes in our warming world. The polar ice sheets of Greenland and Antarctica are one major climate archive, which record information about local air temperatures by means of the isotopic composition of the water molecules embedded in the ice. However, this temperature proxy is, as any indirect climate data, not a perfect recorder of past climatic variations. Apart from local air temperatures, a multitude of other processes affect the mean and variability of the isotopic data, which hinders their direct interpretation in terms of climate variations. This applies especially to regions with little annual accumulation of snow, such as the Antarctic Plateau. While these areas in principle allow for the extraction of isotope records reaching far back in time, a strong corruption of the temperature signal originally encoded in the isotopic data of the snow is expected. This dissertation uses observational isotope data from Antarctica, focussing especially on the East Antarctic low-accumulation area around the Kohnen Station ice-core drilling site, together with statistical and physical methods, to improve our understanding of the spatial and temporal isotope variability across different scales, and thus to enhance the applicability of the proxy for estimating past temperature variability. The presented results lead to a quantitative explanation of the local-scale (1–500 m) spatial variability in the form of a statistical noise model, and reveal the main source of the temporal variability to be the mixture of a climatic seasonal cycle in temperature and the effect of diffusional smoothing acting on temporally uncorrelated noise. These findings put significant limits on the representativity of single isotope records in terms of local air temperature, and impact the interpretation of apparent cyclicalities in the records. Furthermore, to extend the analyses to larger scales, the timescale-dependency of observed Holocene isotope variability is studied. This offers a deeper understanding of the nature of the variations, and is crucial for unravelling the embedded true temperature variability over a wide range of timescales.
    Type of Medium: Dissertations
    Pages: xxi, 197 Seiten , Illustrationen, Diagramme
    Language: English
    Note: Contents: 1 General introduction. - 1.1 Challenges of isotope-based temperature reconstructions. - 1.2 Thesis overview. - 1.3 Author contributions. - 2 Theoretical background. - 2.1 The isotopic composition of firn and ice. - 2.1.1 Fractionation of water isotopologues. - 2.1.2 Relationship with temperature. - 2.1.3 Measuring of the isotopic composition. - 2.2 Processes within the firn column. - 2.2.1 The firn column of polar ice sheets. - 2.2.2 The density of firn. - 2.2.3 The temperature profile of firn. - 2.2.4 Vapour diffusion in firn. - 2.3 Internal climate variability. - 3 Regional climate signal vs.local noise: a two-dimensional view of water isotopes. - 3.1 Introduction. - 3.2 Data and methods. - 3.3 Results. - 3.3.1 Trench isotope records. - 3.3.2 Single-profile representativity. - 3.3.3 Mean trench profiles. - 3.3.4 Spatial correlation structure. - 3.3.5 Statistical noise model. - 3.4 Discussion. - 3.4.1 Local noise vs. regional climate signal. - 3.4.2 Representativity of isotope signals. - 3.4.3 Implications. - 3.5 Conclusions. - 3.6 Appendix A: Derivation of noise model. - 3.6.1 Definitions. - 3.6.2 Derivation of model correlations. - 3.6.3 Estimation of parameters. - 3.7 Appendix B: Noise level after diffusion. - 4 Constraints on post-depositional isotope modifications in east antarctic firn. - 4.1 Introduction. - 4.2 Data and methods. - 4.2.1 Sampling and measurements. - 4.2.2 Trench depth scale. - 4.2.3 Spatial variability of trench profiles. - 4.2.4 Quantification of downward advection, densification and diffusion. - 4.2.5 Statistical tests. - 4.3 Results. - 4.3.1 Comparison of T15 and T13 isotope data. - 4.3.2 Expected isotope profile changes. - 4.3.3 Temporal vs. spatial variability. - 4.4 Discussion. - 4.4.1 Densification, diffusion and stratigraphic noise. - 4.4.2 Additional post-depositional modifications. - 4.5 Conclusions. - 5 On the similarity and apparent cycles of isotope variations. - 5.1 Introduction. - 5.2 Data and Methods. - 5.2.1 Data. - 5.2.2 Spectral analysis. - 5.2.3 Rice’s formula. - 5.2.4 Cycle length and amplitude estimation. - 5.2.5 Model for vertical isotope profiles. - 5.3 Results. - 5.3.1 Spectral analysis of isotope profiles. - 5.3.2 Theoretical and observed cycle length. - 5.3.3 Illustrative examples. - 5.3.4 Depth dependency of cycle length. - 5.3.5 Simulated vs. observed isotope variations. - 5.4 Discussion and summary. - 5.5 Conclusions. - 5.6 Appendix A: Input sensitivity. - 5.7 Appendix B: Additional results. - 5.8 Appendix C: Spectral significance testing. - 6 Timescale-dependency of antarctic isotope variations. - 6.1 Introduction. - 6.2 Data and methods. - 6.2.1 DML and WAIS isotope records. - 6.2.2 Spectral model. - 6.2.3 Timescale-dependent signal-to-noise ratio. - 6.2.4 Effects of diffusion and time uncertainty. - 6.2.5 Present-day temperature decorrelation. - 6.3 Results. - 6.3.1 Illustration of model approach. - 6.3.2 DML and WAIS isotope variability. - 6.4 Discussion. - 6.4.1 Interpretation of noise spectra. - 6.4.2 Interpretation of signal spectra. - 6.4.3 Signal-to-noise ratios. - 6.4.4 Differences between DML and WAIS. - 6.5 Conclusions. - 7 Declining temperature variability from LGM to holocene. - 8 General discussion and conclusions. - 8.1 Short-scale spatial and temporal isotope variability. - 8.1.1 Local spatial variability. - 8.1.2 Seasonal to interannual variability. - 8.1.3 Spatial vs. temporal variability. - 8.2 Extension to longer scales. - 8.2.1 Spatial vs. temporal variability on interannual timescales. - 8.2.2 Holocene and longer timescales. - 8.3 Concluding remarks and outlook. - Bibliography. - A Methods to: declining temperature variability from lgm to holocene. - A.1 Temperature proxy data. - A.2 Model-based temperature and variability change. - A.3 Temperature recalibration of proxy records. - A.3.1 Recalibration of ice-core records. - A.3.2 Recalibration of marine records. - A.4 Variance and variance ratio estimation. - A.5 Noise correction. - A.5.1 Testing effect of noise correction. - A.6 Effect of ecological adaption and bioturbation. - A.7 Effect of proxy sampling locations. - B Layering of surface snow and firn: noise or seasonal signal?. - B.1 Introduction. - B.2 Materials and methods. - B.2.1 Firn-core density profiles. - B.2.2 Trench density profiles. - B.2.3 Dielectric profiling and density estimates. - B.2.4 Comparison of DEP and CT density. - B.2.5 Ion measurements. - B.3 Results. - B.3.1 2-D trench density data. - B.3.2 Spatial correlation structure. - B.3.3 Comparison of mean density, isotope and impurity profiles. - B.3.4 Spectral analysis of vertical density data. - B.4 Discussion. - B.4.1 Spatial variability. - B.4.2 Representativeness of single profiles. - B.4.3 Seasonal cycle in snow density. - B.4.4 Density layering in firn and impurities. - B.5 Conclusions. - Acknowledgements - Danksagung.
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  • 3
    Call number: AWI G5-20-94097
    Type of Medium: Dissertations
    Pages: vi, 127 Seiten , Illustrationen, Diagramme, Karten
    Language: English
    Note: Dissertation, Universität Potsdam, 2020 , Table of contents Abstract Kurzfassung Table of contents Chapter 1: Introduction 1.1 The challenge of proxy uncertainties 1.2 Aims and approaches 1.3 Thesis outline and author's contributions Chapter 2: Comparing methods for analysing time scale dependent correlations in irregularly sampled time series data 2.1 Abstract 2.2 Introduction 2.3 Methods 2.3.1 Time scale dependency 2.3.2 Irregularity 2.3.3 Surrogate data 2.3.3.1 Construction of surrogate signals 2.3.3.2 Construction of irregular sampling 2.3.4 Evaluation of the estimation methods 2.4 Results 2.4.1 Correlation of red signal - white noise time series 2.4.2 Correlation of white signal - white noise time series 2.5 Discussion 2.5.1 Effect of irregularity and non-simultaneousness in sampling 2.5.2 Choosing the best method 2.5.2.1 Handling irregularity 2.5.2.2 Accounting for time scale dependency 2.5.3 Example application to observed proxy records 2.6 Conclusion 2.7 Computer code availability 2.8 Acknowledgements 2.9 Appendix 2-A. Significance test for time scale dependent correlation estimates Chapter 3: Empirical estimate of the signal content of Holocene temperature proxy records 3.1 Abstract 3.2 Introduction 3.3 Data 3.3,1 Proxy records 3.3.2 Climate model simulations 3.4 Method 3.4.1 Approach and assumptions 3.4.2 Spatial correlation structure of model vs. reanalysis data 3.4.3 Processing steps 3.4.3.1 Estimation of the spatial correlation structure 3.4.3.2 Estimation of the SNRs 3.5 Results 3.5.1 Spatial correlation structure and correlation decay length 3.5.2 SNR estimates 3.6 Discussion 3.6.1 Spatial correlation structure of model simulations 3.6.2 Finite number of proxy records 3.6.3 Proxy-specific recording of climate variables 3.6.4 Time uncertainty and non-climatic components of the proxy signal 3.6.5 Implications and future steps forward 3.7 Conclusion 3.8 Code availability 3.9 Data availability 3.10 Acknowledgements Chapter 4: Testing the consistency of Holocene and Last Glacial Maximum spatial correlations in temperature proxy records 4.1 Abstract 4.2 Introduction 4.3 Data 4.4 Method 4.4.1 Approach and assumptions 4.4.2 Holocene and LGM spatial correlation structure from climate model simulation 4.4.3 Effect of changes in climate variability on the predicted correlations 4.4.4 Effect of changes in time uncertainty on the predicted correlations 4.4.S Estimating the surrogate-based LGM spatial correlation and accounting for parameter uncertainty 4.5 Results 4.6 Discussion 4.6.1 Proxy-specific recording and finite number of records 4.6.2 Time uncertainty of proxy records 4.6.3 Contrary behaviour of U K'37 records 4.6.4 Spatial correlation structure and orbital trends 4.7 Conclusion 4.8 Acknowledgements 4.9 Appendix 4-A. Deriving the effect of a different signal variance on the correlation Chapter 5: Synthesis 5.1 Irregular sampling and time scale dependent correlations 5.2 Spatial correlation structure of proxy records 5.3 Consistency of spatial correlations for different climate states 5.4 Signal content of proxy records 5.5 Concluding remarks and Outlook Chapter A: Supplement of Chapter 3 - Empirical estimate of the signal content of Holocene temperature proxy records A.1 Supplementary Figures A.2 Supplementary Tables Chapter B: Supplement of Chapter 4 - Testing the consistency of Holocene and Last Glacial Maximum spatial correlations of temperature proxy records 8.1 Supplementary Figures 8.2 Supplementary Tables References Danksagung Eidesstattliche Erklärung
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  • 4
    ISSN: 1434-6036
    Keywords: 05.40.+j ; 05.70.Fh
    Source: Springer Online Journal Archives 1860-2000
    Topics: Physics
    Notes: Abstract The collective behavior of overdamped nonlinear noise-driven oscillators coupled via mean field is investigated numerically. When a coupling constant is increased, a transition in the dynamics of the mean field is observed. This transition scales with the number of oscillators and disappears when this number tends to infinity. Analytical arguments explaining the observed scaling are presented.
    Type of Medium: Electronic Resource
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  • 5
    Publication Date: 2015-05-11
    Description: The Asian monsoon system is an important tipping element in Earth's climate with a large impact on human societies in the past and present. In light of the potentially severe impacts of present and future anthropogenic climate change on Asian hydrology, it is vital to understand the forcing mechanisms of past climatic regime shifts in the Asian monsoon domain. Here we use novel recurrence network analysis techniques for detecting episodes with pronounced non-linear changes in Holocene Asian monsoon dynamics recorded in speleothems from caves distributed throughout the major branches of the Asian monsoon system. A newly developed multi-proxy methodology explicitly considers dating uncertainties with the COPRA (COnstructing Proxy Records from Age models) approach and allows for detection of continental-scale regime shifts in the complexity of monsoon dynamics. Several epochs are characterised by non-linear regime shifts in Asian monsoon variability, including the periods around 8.5–7.9, 5.7–5.0, 4.1–3.7, and 3.0–2.4 ka BP. The timing of these regime shifts is consistent with known episodes of Holocene rapid climate change (RCC) and high-latitude Bond events. Additionally, we observe a previously rarely reported non-linear regime shift around 7.3 ka BP, a timing that matches the typical 1.0–1.5 ky return intervals of Bond events. A detailed review of previously suggested links between Holocene climatic changes in the Asian monsoon domain and the archaeological record indicates that, in addition to previously considered longer-term changes in mean monsoon intensity and other climatic parameters, regime shifts in monsoon complexity might have played an important role as drivers of migration, pronounced cultural changes, and the collapse of ancient human societies.
    Repository Name: EPIC Alfred Wegener Institut
    Type: Article , NonPeerReviewed
    Format: application/pdf
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  • 6
    Electronic Resource
    Electronic Resource
    [s.l.] : Macmillan Magazines Ltd.
    Nature 392 (1998), S. 239-240 
    ISSN: 1476-4687
    Source: Nature Archives 1869 - 2009
    Topics: Biology , Chemistry and Pharmacology , Medicine , Natural Sciences in General , Physics
    Notes: [Auszug] It is widely accepted that cardiac and respiratory rhythms in humans are unsynchronised. However, a newly developed data analysis technique allows any interaction that does occur in even weakly coupled complex systems to be observed. Using this technique, we found long periods of hidden ...
    Type of Medium: Electronic Resource
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  • 7
    ISSN: 1573-093X
    Source: Springer Online Journal Archives 1860-2000
    Topics: Physics
    Notes: Abstract Using the theory of nonlinear dynamical systems a time-series analysis of a pulsation event in solar radio emission suggests that there exists a low-dimensional attractor. The power spectrum cannot be interpreted as a superposition of periodic components. Estimates of the maximum Lyapunov exponent and the Kolmogorov entropy give some hints to deterministic chaos. Consequences for the physical modelling of the event are discussed.
    Type of Medium: Electronic Resource
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  • 8
    Electronic Resource
    Electronic Resource
    Springer
    Solar physics 119 (1989), S. 399-411 
    ISSN: 1573-093X
    Source: Springer Online Journal Archives 1860-2000
    Topics: Physics
    Notes: Abstract A time series analysis of a pulsation event in solar radio emission provides an evolution from a regular doubly periodic phase to an irregular behaviour. Applying some techniques developed in the theory of nonlinear dynamic systems to this irregular stage suggests that there exists a low-dimensional attractor. Estimates of the maximum Lyapunov exponent give some evidence to deterministic chaos. The sudden transition from a regular to a chaotic structure is identified as a part of the Ruelle-Takens-Newhouse route to chaos which is typical in nonlinear systems. It is checked whether this pulsation event may be interpreted in terms of known pulsation models. Consequences for models, which are suitable to describe such an evolution, are discussed.
    Type of Medium: Electronic Resource
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  • 9
    Electronic Resource
    Electronic Resource
    Springer
    Space science reviews 68 (1994), S. 171-184 
    ISSN: 1572-9672
    Keywords: Radio emission of the sun ; Solar bursts ; Data analysis ; Nonlinear dynamics
    Source: Springer Online Journal Archives 1860-2000
    Topics: Physics
    Notes: Abstract The application of chaos theory has become popular to understand the nature of various features of solar activity because most of them are far from regular. The usual approach, however, that is based on finding low-dimensional structures of the underlying processes seems to be successful only in a few exceptional cases, such as in rather coherent phenomena as coronal pulsations. It is important to note that most phenomena in solar radio emission are more complex. We present two kinds of techniques from nonlinear dynamics which can be useful to analyse such phenomena: • Fragmentation processes observed in solar spike events are studied by means of symbolic dynamics methods. Different measures of complexity calculated from such observations reveal that there is some order in this fragmentation. • Bursts are a typical transient phenomenon. To study energization processes causing impulsive microwave bursts, the wavelet analysis is applied. It exhibits structural differences of the pre- and post-impulsive phase in cases where the power spectra of both are not distinct.
    Type of Medium: Electronic Resource
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  • 10
    Electronic Resource
    Electronic Resource
    Woodbury, NY : American Institute of Physics (AIP)
    Chaos 7 (1997), S. 680-687 
    ISSN: 1089-7682
    Source: AIP Digital Archive
    Topics: Physics
    Notes: We consider phase synchronization of chaotic continuous-time oscillator by periodic external force. Phase-locking regions are defined for unstable periodic cycles embedded in chaos, and synchronization is described in terms of these regions. A special flow construction is used to derive a simple discrete-time model of the phenomenon. It allows to describe quantitatively the intermittency at the transition to phase synchronization. © 1997 American Institute of Physics.
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