Location of Repository

Scaling and a Fokker-Planck model for fluctuations in geomagnetic indices and comparison with solar wind as seen by Wind and ACE

By B. Hnat, Sandra C. Chapman and G. (George) Rowlands


The evolution of magnetospheric indices on temporal scales shorter than that of substorms is characterized by bursty, intermittent events that may arise from turbulence intrinsic to the magnetosphere or that may reflect solar wind-magnetosphere coupling. This leads to a generic problem of distinguishing between the features of the system and those of the driver. We quantify scaling properties of short-term (up to few hours) fluctuations in the geomagnetic indices AL and AU during solar minimum and maximum, along with the parameter that is a measure of the solar wind driver. We find that self-similar statistics provide a good approximation for the observed scaling properties of fluctuations in the geomagnetic indices, regardless of the solar activity level, and in the parameter at solar maximum. This self-similarity persists for fluctuations on timescales at least up to about 1–2 hours. The scaling exponent of AU index fluctuations show dependence on the solar cycle, and the trend follows that found in the scaling of fluctuations in . The values of their corresponding scaling exponents, however, are always distinct. Fluctuations in the AL index are insensitive to the solar cycle, as well as being distinct from those in the parameter. This approximate self-similar scaling leads to a Fokker-Planck model which, we show, captures the probability density function of fluctuations and provides a stochastic dynamical equation (Langevin equation) for time series of the geomagnetic indices

Topics: QB
Publisher: American Geophysical Union
Year: 2005
OAI identifier: oai:wrap.warwick.ac.uk:3870

Suggested articles



  1. (2002b), Scale-free statistics of spatiotemporal auroral emissions as depicted by POLAR UVI images: Dynamic magnetosphere is an avalanching system, doi
  2. (2003b), Intermittency, scaling, and the Fokker-Planck approach to fluctuations of the solar wind bulk plasma parameters as seen by the WIND spacecraft, doi
  3. (2004a), Scale-free avalanching and a loading-unloading cycle in a driven current-sheet model, paper presented
  4. (1978). A study of geomagnetic storms, doi
  5. (2001). Avalanching and self organised criticality: a paradigm for magnetospheric dynamics?,
  6. Baker (2004b), Reconnection and scale-free avalanching in a driven current-sheet model, doi
  7. (1992). Bursty bulk flows in the inner central plasma sheet, doi
  8. (2003). Cellular automata model of magnetospheric-ionospheric coupling, doi
  9. (2003). Combining global and multi-scale features in a description of doi
  10. (2001). Comparative study of dynamical critical scaling in the auroral electrojet index versus solar wind fluctuations, doi
  11. (1993). Correlation dimension and affinity of AE data and bicolored noise, doi
  12. (2000). Critical Phenomena in Natural Sciences; Chaos, Fractals, Selforganization and Disorder: Concepts and Tools, doi
  13. (2003). Evaluation of spreading critical exponents from the spatiotemporal evolution of emission regions in the nighttime aurora, doi
  14. (2000). Evidence for a solar wind origin of the power law burst lifetime distribution of the AE indices, doi
  15. (1999). Evidence for intermittency in Earth’s plasma sheet and implications for self-organized criticality, doi
  16. Freeman (2003a), Scaling in long term data sets of geomagnetic indices and solar wind e as seen by WIND spacecraft, doi
  17. (2002). Intermittency in the solar wind: A comparison between solar minimum and maximum using Ulysses data, doi
  18. (2003). Intermittency of magnetospheric dynamics through non-Gaussian distribution function of PC-index fluctuations, doi
  19. (2000). Is the dynamic magnetosphere an avalanching system?, doi
  20. Kova ´cs (2002), Scaling and singularity characteristics of solar wind and magnetospheric fluctuations, Nonlinear
  21. (1998). Low frequency 1/f-like fluctuations of the AE-index as a possible manifestation of self-organized criticality in the magnetosphere, doi
  22. (1992). Low-dimensional behavior and symmetry breaking of stochastic systems near criticality: Can these effects be observed in space and in the laboratory?, doi
  23. Mewaldt (2003), Modes of energy transfer from the solar wind to the inner magnetosphere, doi
  24. (1996). Multifractal structure of auroral electrojet index data, doi
  25. Multiscale dynamics and robust critical scaling in a continuum current sheet model, doi
  26. (1998). Non-Gaussian distribution function of AE-index fluctuations: Evidence for time intermittency, doi
  27. (1991). On the apparent randomness of substorm onset, doi
  28. (2000). Phase transition-like behavior of the magnetosphere during substorms, doi
  29. (2004). Power law probability distributions of multiscale auroral dynamics from groundbased TV observations, doi
  30. (2003). Probability distribution invariance of 1-minute auroral-zone geomagnetic field fluctuations, doi
  31. (2000). Role of the driver in the dynamics of a coupled-map model of the magnetotail: Does the magnetosphere act as a low-pass filter?, doi
  32. (2005). Scaling collapse and structure functions: Identifying self-affinity in finite length time series, doi
  33. (1998). Scaling laws from geomagnetic time series,
  34. (2003). Solar wind coupling to and predictability of ground magnetic fields and their time derivatives, doi
  35. (1997). Structure function measurements of the intermittent MHD turbulent cascade, Nonlinear doi
  36. (2000). The nonlinear dynamics of space weather, doi
  37. (1990). The nonlinear response of AE to the IMF Bs driver: A spectral break at 5 hours, doi
  38. (1996). The organized nonlinear dynamics of the magnetosphere, doi
  39. (1999). The solar-wind driven magnetosphere-ionosphere as a complex dynamical system, doi
  40. (1995). Turbulence: The Legacy of A. doi
  41. (1988). Vetterling doi
  42. Vo ¨ro ¨s (2001), Wavelet-based filtering of intermittent events from geomagnetic time series, doi

To submit an update or takedown request for this paper, please submit an Update/Correction/Removal Request.