http://hdl.handle.net/2122/107 Search the Channel search http://www.earth-prints.org/simple-search http://hdl.handle.net/2122/4072 Title: A Revised Forest Fire Model Non-Quasistatically Driven for the Sporadic Activity of the Earth’s Magnetotail <br/> <br/>Authors: De Michelis, P.; Istituto Nazionale di Geofisica e Vulcanologia, Sezione Roma2, Roma, Italia; Consolini, G.; Istituto di Fisica dello Spazio Interplanetario, CNR, Via Fosso del Cavaliere 100, 00133 Roma, Italy <br/> <br/>Editors: Sawaya-Lacoste, H.; ESA Publications Division <br/> <br/>Abstract: The energy release during magnetospheric substorms in response to solar wind changes consists of two main physical processes: the directly-driven and the unloading processes. Recent analysis on the sporadic activity related to the unloading process seems to indicate that the magnetospheric response to solar wind changes might resemble the behaviour of an out-of-equilibrium system near a marginally stable point (critical point). Here, we present a modified version of the well-known forest-fire cellular automaton (FFM) not quasistatically driven for the sporadic activity of the energy release in the geotail regions as revealed by the auroral electrojet index. Tue, 29 Jan 2002 22:58:59 GMT http://hdl.handle.net/2122/4026 Title: On the Earth’s magnetospheric dynamics: Nonequilibrium evolution and the fluctuation theorem <br/> <br/>Authors: Consolini, G.; Istituto di Fisica dello Spazio Interplanetario, INAF, Rome, Italy; De Michelis, P.; Istituto Nazionale di Geofisica e Vulcanologia, Sezione Roma2, Roma, Italia; Tozzi, R.; Istituto Nazionale di Geofisica e Vulcanologia, Sezione Roma2, Roma, Italia <br/> <br/>Abstract: The Earth’s magnetosphere evolves as an out-of-equilibrium system due to the continuous coupling with the solar wind and the Earth’s ionosphere. We test the validity of the symmetries implied in the Fluctuation Theorem for the magnetospheric dynamics by investigating the long-term evolution of the Earth’s magnetospheric ring current, as monitored by the geomagnetic Dst index. We find that the symmetries implied by the Fluctuation Theorem are all verified, thus providing a proof of the existence of a steady state far from equilibrium for the Earth’s magnetosphere. A possible link between the Dst index and the entropy production rate is also proposed and discussed. Wed, 20 Aug 2008 22:58:59 GMT http://hdl.handle.net/2122/4023 Title: Fractal time statistics of AE-index burst waiting times: evidence of metastability <br/> <br/>Authors: Consolini, G.; Istituto di Fisica dello Spazio Interplanetario – CNR, Roma, Italy; De Michelis, P.; Istituto Nazionale di Geofisica e Vulcanologia, Sezione Roma2, Roma, Italia <br/> <br/>Abstract: Recent observations and analyses evidenced that the magnetotail, as well as the magnetospheric dynamics are characterised by a scale-free behaviour and intermittence. These results, along with numerical simulations on cellular automata, suggest that the observed scale-invariance may be due to forced and/or self-organised criticality (FSOC), meaning that the magnetotail operates near a marginally stable state (Chang, 1999). On the other hand, it was underlined that a complex magnetic field topology in the geotail regions may play a relevant role in the impulsive energy relaxation (Consolini and Chang, 2001). Mon, 29 Oct 2001 22:58:59 GMT http://hdl.handle.net/2122/4022 Title: A revised forest-fire cellular automaton for the nonlinear dynamics of the Earth’s magnetotail <br/> <br/>Authors: Consolini, G.; Istituto di Fisica dello Spazio Interplanetario, Consiglio Nazionale delle Ricerche-CNR, Via Fosso del Cavaliere 100, 00133 Roma, Italy; De Michelis, P.; Istituto Nazionale di Geofisica e Vulcanologia, Sezione Roma2, Roma, Italia <br/> <br/>Abstract: Recent observations and numerical simulations seem to suggest that the Earth’s magnetotail plasma could exist in a near-criticality configuration, and that many features of the magnetospheric response to solar wind changes could be described by avalanche models displaying self-organized criticality. Further evidences of this near-criticality dynamics have been found analyzing the statistical features of the auroral electrojet (AE) index. Here, we present a cellular automaton, based on a revised version of the well-known forest-fire model, for the nonlinear dynamics of the Earth’s magnetotail. This simple model, chaotically driven using a 1-d coupled map, is able to capture many of the statistical features of the magnetospheric response to solar wind changes. The results, compared with previous analyses of the AE-index features, are discussed in the framework of a near-criticality dynamics of the magnetospheric tail plasma. Wed, 29 Aug 2001 22:58:59 GMT