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Étude multi-instrumentale de la dynamique des structures aurorales côté jour et côté nuit : couplage avec la magnétosphère et le milieu interplanétaire

Abstract : The dynamics of the magnetosphere-ionosphere system is controlled by the solar wind through small scale processes affecting magnetospheric flux tubes. In a series of multi-instrument studies, we investigate the dynamics of these flux tubes simultaneously in the magnetosphere and in the ionosphere. In a first part, we give a general description of the magnetosphere-ionosphere system, and we analyse the recent work on meso-scale structures and available experimental measurements used for their description. In the second part of this thesis, we study the dynamic responses of the dayside system. We perform the first quantitative comparison between magnetospheric and ionospheric plasma and phase velocities of flux tubes generated by transient reconnection. We quantify the motion of dayside magnetospheric boundaries in response to variations of the north-south component of the interplanetary magnetic field. We also show that solar wind pressure pulses can trigger reconnection events during southward interplanetary magnetic field. We confirm also that the associated ionospheric convection flow bursts are fossil signatures of the reconnection. In the third part of this thesis, we study the electrodynamics of meso-scale auroral structures in the dayside and in the nightside. First, we present the first direct observation of the parallel currents associated with a dayside magnetospheric reconnected flux tube. These currents including the closure horizontal Pedersen current, form a balanced system, isolated from the global scale magnetospheric currents. Then, we model the ionospheric closure of the parallel currents in a meso-scale nightside arc. We have tested a one-dimensional and a two-dimensional model. Although the two-dimensional model gives better results, it suffers lacks experimental input data. This work illustrates the role of meso-scale processes in the global dynamics of the magnetosphere.
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https://tel.archives-ouvertes.fr/tel-00008894
Contributor : Aurélie Marchaudon <>
Submitted on : Tuesday, March 29, 2005 - 6:22:45 PM
Last modification on : Friday, October 23, 2020 - 4:38:05 PM
Long-term archiving on: : Friday, September 14, 2012 - 12:30:19 PM

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  • HAL Id : tel-00008894, version 1

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Aurélie Marchaudon. Étude multi-instrumentale de la dynamique des structures aurorales côté jour et côté nuit : couplage avec la magnétosphère et le milieu interplanétaire. Autre. Université de Versailles-Saint Quentin en Yvelines, 2003. Français. ⟨tel-00008894⟩

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