Modelling the Compressibility of Saturn's Magnetosphere

Friday, 19 December 2014
Nicholas A Achilleos1,2, Christopher Stephen Arridge3, Patrick Guio1,2, Nathan Michael Pilkington1,2, Adam Masters4, Nick Sergis5, Andrew J Coates2,6 and Michele Karen Dougherty7, (1)University College London, London, United Kingdom, (2)University College London, Centre for Planetary Sciences (at UCL/Birkbeck), London, United Kingdom, (3)University of Lancaster, Department of Physics, Lancaster, United Kingdom, (4)Imperial College London, Blackett Laboratory, London, SW7, United Kingdom, (5)National and Kapodistrian University of Athens, Athens, Greece, (6)University College London, Mullard Space Science Laboratory, London, United Kingdom, (7)Imperial College London, Blackett Laboratory, London, United Kingdom
Work presented at this meeting by Pilkington et al. shows observational evidence that Saturn's magnetopause may be significantly affected by variations in the beta parameter of the outer magnetospheric plasma, as well as by variations in solar wind dynamic pressure. In order to model the influence of these two physical parameters on magnetospheric compressibility, we construct magnetostatic models of the dayside magnetosphere of the planet using the UCL Magnetodisc Model in 'Saturn mode'. For different values of hot plasma beta, which span the observed range at Saturn, we construct a model power law expressing the relation between between magnetopause standoff distance and solar wind dynamic pressure (assumed to be equal to total magnetic plus plasma pressure at the model's outer boundary). We comment on the behaviour of the magnetospheric compressibility and scale according to: (1) The response of the magnetopause location to changes in solar wind dynamic pressure at fixed plasma beta; and (2) The response of the system which ensues when plasma beta varies at fixed solar wind dynamic pressure.