Now showing items 10-29 of 68

  • Classification of robust heteroclinic cycles for vector fields in R3 with symmetry 

    Hawker, David; Ashwin, Peter (Institute of Physics, 2005)
    We consider a classification of robust heteroclinic cycles in the positive octant of R3 under the action of the symmetry group (Z2)3. We introduce a coding system to represent different classes up to a topological equivalence, ...
  • Climate–carbon cycle feedback analysis: results from the C4MIP model intercomparison 

    Friedlingstein, P.; Cox, Peter M.; Betts, R. A.; Bopp, L.; Von Bloh, W.; Brovkin, Victor; Cadule, P.; Doney, S.; Eby, M.; Fung, I.; Bala, G.; John, J.; Jones, Chris D.; Joos, F.; Kato, T.; Kawamiya, M.; Knorr, W.; Lindsay, K.; Matthews, H. D.; Raddatz, T.; Rayner, P.; Reick, C.; Roeckner, E.; Schnitzler, K.-G.; Schnur, R.; Strassmann, K.; Weaver, A. J.; Yoshikawa, C.; Zeng, N. (American Meteorological Society, 2006)
    Eleven coupled climate-carbon cycle models used a common protocol to study the coupling between climate change and the carbon cycle. The models were forced by historical emissions and the Intergovernmental Panel on Climate ...
  • Comparing the degree of land–atmosphere interaction in four atmospheric general circulation models 

    Koster, Randal D.; Dirmeyer, Paul A.; Hahmann, Andrea N.; Ijpelaar, Ruben; Tyahla, Lori; Cox, Peter M.; Suarez, Max J. (American Meteorological Society, 2002)
    The strength of the coupling between the land and the atmosphere, which controls, for example, the degree to which precipitation-induced soil moisture anomalies affect the overlying atmosphere and thereby the subsequent ...
  • Conditions for sink-to-source transitions and runaway feedbacks from the land carbon cycle 

    Cox, Peter M.; Huntingford, Chris; Jones, Chris D. (Cambridge University Press, 2006-02)
    The first GCM climate-carbon cycle simulation indicated that the land biosphere could provide a significant acceleration of 21st century climate change (Cox et al. 2000). In this numerical experiment the carbon storage was ...
  • Convergence to local random attractors 

    Ashwin, Peter; Ochs, Gunter (Taylor & Francis, 2003)
    Random attractors allow one to classify qualitative and quantitative aspects of the long-time behaviour of stochastically forced systems viewed as random dynamical systems (RDS) in an analogous way to attractors for ...
  • Cycling chaotic attractors in two models for dynamics with invariant subspaces 

    Ashwin, Peter; Rucklidge, Alastair M.; Sturman, Rob (American Institute of Physics, 2004)
    Nonergodic attractors can robustly appear in symmetric systems as structurally stable cycles between saddle-type invariant sets. These saddles may be chaotic giving rise to "cycling chaos." The robustness of such attractors ...
  • Decelerating defects and non-ergodic critical behaviour in a unidirectionally coupled map lattice 

    Ashwin, Peter; Sturman, Rob (Elsevier, 2003)
    We examine a coupled map lattice (CML) consisting of an infinite chain of logistic maps coupled in one direction by inhibitory coupling. We find that for sufficiently strong coupling strength there are dynamical states ...
  • Discrete computation using a perturbed heteroclinic network 

    Ashwin, Peter; Borresen, Jon (Elsevier, 2005)
    Transient synchronization into clusters appears in many biological and physical systems and seems to be important for computation within neural systems. In this paper we show how one can robustly and effectively perform ...
  • Dynamics on networks of cluster states for globally coupled phase oscillators 

    Ashwin, Peter; Orosz, Gábor; Wordsworth, John; Townley, Stuart (Society for Industrial and Applied Mathematics, 2007)
    Systems of globally coupled phase oscillators can have robust attractors that are heteroclinic networks. We investigate such a heteroclinic network between partially synchronized states where the phases cluster into three ...
  • Effective diffusion of scalar fields in a chaotic flow 

    Turner, M. R.; Gilbert, Andrew D.; Thuburn, John (American Institute of Physics, 2008)
    The advection of a tracer field in a fluid flow can create complex scalar structures and increase the effect of weak diffusion by orders of magnitude. One tool to quantify this is to measure the flux of scalar across contour ...
  • Effects of frozen soil on soil temperature, spring infiltration, and runoff: results from the PILPS 2(d) experiment at Valdai, Russia 

    Luo, Lifeng; Robock, Alan; Vinnikov, Konstantin Y.; Schlosser, C. Adam; Slater, Andrew G.; Boone, Aaron; Braden, Harald; Cox, Peter M.; De Rosnay, Patricia; Dickinson, Robert E.; Dai, Yongjiu; Duan, Qingyun; Etchevers, Pierre; Henderson-Sellers, Ann; Gedney, Nicola; Gusev, Yevgeniy M.; Habets, Florence; Kim, Jinwon; Kowalczyk, Eva; Mitchell, Ken; Nasonova, Olga N.; Noilhan, Joel; Pitman, Andrew; Schaake, John; Shmakin, Andrey B.; Smirnova, Tatiana G.; Wetzel, Peter; Xue, Yongkang; Yang, Zong-Liang; Zeng, Qing-Cun (American Meteorological Society, 2009-12-18)
    The Project for Intercomparison of Land-Surface Parameterization Schemes phase 2(d) experiment at Valdai, Russia, offers a unique opportunity to evaluate land surface schemes, especially snow and frozen soil parameterizations. ...
  • Elliptic behaviour in the sawtooth standard map 

    Ashwin, Peter (Elsevier, 1997)
    This paper examines the standard map with sawtooth nonlinearity when the eigenvalues of the Jacobian lie on the unit circle. This is an area-preserving map of the torus to itself that is linear except on a line on which ...
  • Encoding via conjugate symmetries of slow oscillations for globally coupled oscillators 

    Ashwin, Peter; Borresen, Jon (American Physical Society, 2004)
    We study properties of the dynamics underlying slow cluster oscillations in two systems of five globally coupled oscillators. These slow oscillations are due to the appearance of structurally stable heteroclinic connections ...
  • Energy-crossing number relations for braided magnetic fields 

    Berger, M.A. (American Physical Society, 1993)
    This Letter derives lower bounds on the energy of braided magnetic fields, based on crossing number techniques pioneered by Freedman and He. Mean crossing numbers are defined for magnetic fields inside a cylinder; for ...
  • Explicit representation of subgrid heterogeneity in a GCM land surface scheme 

    Essery, R. L. H.; Best, M. J.; Betts, R. A.; Cox, Peter M.; Taylor, Christopher M. (American Meteorological Society, 2003)
    A land surface scheme that may be run with or without a tiled representation of subgrid heterogeneity and includes an implicit atmospheric coupling scheme is described. Simulated average surface air temperatures and diurnal ...
  • Extreme Sensitivity to Detuning for Globally Coupled Phase Oscillators 

    Ashwin, Peter; Burylko, Oleksandr; Maistrenko, Yuri; Popovych, Oleksandr (American Physical Society, 2006)
    We discuss the sensitivity of a population of coupled oscillators to differences in their natural frequencies, i.e., to detuning. We argue that for three or more oscillators, one can get great sensitivity even if the ...
  • Fast simulation of phase-change processes in chalcogenide alloys using a Gillespie-type cellular automata approach 

    Ashwin, Peter; Patnaik, B. S. V.; Wright, C. David (American Institute of Physics, 2008)
    A stochastic cellular automata simulator capable of spatiotemporal modeling of the crystallization and amorphization behavior of phase-change materials during the complex annealing cycles used in optical and electrical ...
  • Fractal properties of forest fires in Amazonia as a basis for modelling pan-tropical burnt area. 

    Fletcher, Imogen; Aragao, Luiz; Lima, André; Shimabukuro, Yosio; Friedlingstein, P. (European Geosciences Union (EGU), 2014)
    Current methods for modelling burnt area in dynamic global vegetation models (DGVMs) involve complex fire spread calculations, which rely on many inputs, including fuel characteristics, wind speed and countless parameters. ...
  • Front propagation in a phase field model with phase-dependent heat absorption 

    Blyuss, Konstantin; Ashwin, Peter; Wright, C. David; Bassom, Andrew P. (Elsevier, 2006)
    We present a model for the spatio-temporal behaviour of films exposed to radiative heating, where the film can change reversibly between amorphous (glassy) and crystalline states. Such phase change materials are used ...
  • GLACE: the global land–atmosphere coupling experiment. Part I: overview 

    Koster, Randal D.; Guo, Zhichang; Dirmeyer, Paul A.; Bonan, Gordon; Chan, Edmond; Cox, Peter M.; Davies, Harvey; Gordon, C. T.; Kanae, Shinjiro; Kowalczyk, Eva; Lawrence, David; Liu, Ping; Lu, Cheng-Hsuan; Malyshev, Sergey; McAvaney, Bryant; Mitchell, Ken; Mocko, David; Oki, Taikan; Oleson, Keith W.; Pitman, Andrew; Sud, Y. C.; Taylor, Christopher M.; Verseghy, Diana; Vasic, Ratko; Xue, Yongkang; Yamada, Tomohito (American Meteorological Society, 2006)
    The Global Land–Atmosphere Coupling Experiment (GLACE) is a model intercomparison study focusing on a typically neglected yet critical element of numerical weather and climate modeling: land–atmosphere coupling strength, ...