Event Details

Magneto-hydrodynamic modelling of the Jovian System by Dr Anthony Sciola (Johns Hopkins University – Applied Physics Lab.)

Explaining plasma and magnetic flux transport in planetary magnetospheres is essential to understanding fundamental magnetospheric phenomena such as the build-up of Earth's ring current or the periodic nature of particle injections at Saturn. Flux-tube entropy is a key quantity governing stability and consequently conditions favourable to transport in the inner magnetosphere, such as those created by magnetotail reconnection and centrifugal mass transport. In this presentation, we will discuss the theory of flux tube entropy in planetary magnetospheres and explore its influence on inner magnetosphere dynamics at both Earth and Saturn. At Earth, magnetotail reconnection creates entropy-depleted flux tubes that then penetrate deep into the magnetosphere, as close as 4-6 R_e. We will discuss recent modeling work, using the GAMERA magnetohydrodynamic (MHD) model coupled with the Rice Convection Model (RCM), which shows that these flows can contribute over half of the total pressure to the storm-time ring current, and that the differing evolution between the plasma and magnetic flux transported by these flows can explain recent observational peculiarities. Inner magnetosphere dynamics at Saturn have an additional complexity in the form of internal mass-loading by Enceladus. We will demonstrate that while centrifugal interchange is more ubiquitous, entropic interchange is a more efficient transporter, and so understanding the interplay between these two mechanisms is essential to understanding the system as a whole.