Abstracts > Abstract list by author > Turc Lucile

Role of the terrestrial bow shock on magnetic clouds' structure: 2. 3D analytical MHD model
Lucile Turc  1@  , Dominique Fontaine  1@  , Emilia Kilpua  2@  , Philippe Savoini  1@  
1 : Laboratoire de Physique des Plasmas  (LPP)  -  Website
Polytechnique - X, Université Paris VI - Pierre et Marie Curie, CNRS : UMR7648, Université Paris XI - Paris Sud
LPP, CNRS/Ecole Polytechnique Route de Saclay 91128 - Palaiseau -  France
2 : Department of Physics, University of Helsinki
P.O. Box 64, 00014 Helsinki -  Finland

Magnetic clouds (MC) figure among the most important drivers of magnetic storms. In the solar wind, they present a very distinctive structure. However, before reaching the magnetosphere, MCs encounter the bow shock which modifies their structure, and therefore may influence their geoeffectivity. In order to understand how the magnetic structure of MCs is altered by the shock, a simple analytical MHD model is used to calculate the magnetic field strength and direction inside the magnetosheath. We present several outputs of the model, corresponding to different MC axis orientations and to different impact parameters. The variation of the magnetic field direction from the solar wind to the magnetosheath appears to be strongly driven by the shock obliquity. Asymmetries due to different shock configurations may arise inside the magnetosheath. Moreover, the magnetic field north-south component can even reverse in some parts of the magnetosheath. The model outputs are compared with spacecraft observations. Finally, we discuss the impact of our conclusions on MCs' geoeffectivity.

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