 |
| Titel |
Hysteresis-controlled instability waves in a scale-free driven current sheet model |
| VerfasserIn |
V. M. Uritsky, A. J. Klimas |
| Medientyp |
Artikel
|
| Sprache |
Englisch
|
| ISSN |
1023-5809
|
| Digitales Dokument |
URL |
| Erschienen |
In: Nonlinear Processes in Geophysics ; 12, no. 6 ; Nr. 12, no. 6 (2005-09-20), S.827-833 |
| Datensatznummer |
250010890
|
| Publikation (Nr.) |
 copernicus.org/npg-12-827-2005.pdf |
|
|
|
|
|
| Zusammenfassung |
| Magnetospheric dynamics is a complex multiscale process whose statistical
features can be successfully reproduced using high-dimensional numerical
transport models exhibiting the phenomenon of self-organized criticality
(SOC). Along this line of research, a 2-dimensional driven current sheet
(DCS) model has recently been developed that incorporates an idealized
current-driven instability with a resistive MHD plasma system
(Klimas et al., 2004a, b). The dynamics of the DCS model is
dominated by the scale-free diffusive energy transport characterized by a
set of broadband power-law distribution functions similar to those governing
the evolution of multiscale precipitation regions of energetic particles in
the nighttime sector of aurora (Uritsky et al., 2002b). The scale-free DCS
behavior is supported by localized current-driven instabilities that can
communicate in an avalanche fashion over arbitrarily long distances thus
producing current sheet waves (CSW). In this paper, we derive the analytical
expression for CSW speed as a function of plasma parameters controlling
local anomalous resistivity dynamics. The obtained relation indicates that
the CSW propagation requires sufficiently high initial current densities,
and predicts a deceleration of CSWs moving from inner plasma sheet regions
toward its northern and southern boundaries. We also show that the shape of
time-averaged current density profile in the DCS model is in agreement with
steady-state spatial configuration of critical avalanching models as
described by the singular diffusion theory of the SOC. Over shorter time
scales, SOC dynamics is associated with rather complex spatial patterns and,
in particular, can produce bifurcated current sheets often seen in
multi-satellite observations. |
| |
|
| Teil von |
|
|
|
|
|
|
|
|