Model‐Based Assessments of Magnetic Reconnection and Kelvin‐Helmholtz Instability at Jupiter's Magnetopause

Abstract

AbstractThe interaction between the solar wind and Jupiter's magnetic field confines the planetary field to the largest magnetosphere in the Solar System. However, the full picture of when and where key processes operate at the magnetopause boundary of the system remains unclear. This is essential for testing understanding with observations and for determining the relative importance of different drivers of Jovian magnetospheric dynamics. Here we present a global analytical model of Jovian magnetopause conditions under steady state, which forms the basis of boundary process assessments. Sites of magnetic reconnection at Jupiter's magnetopause are expected to be in regions of sufficiently high magnetic shear across the boundary, controlled by the orientation of the interplanetary magnetic field. Reconnection rates are also most sensitive to changes in the highly variable IMF, followed by changes in the solar wind plasma mass density. The largest plasma flow shear across the boundary is in the equatorial dawn region, producing a region that is typically unstable to growth of the Kelvin‐Helmholtz (K‐H) instability. Compared to magnetopause reconnection site locations, this K‐H‐unstable region at dawn is less sensitive to changing conditions. Motion of K‐H boundary perturbations typically includes dawn‐to‐dusk motion across the subsolar region. Model‐predicted reconnection voltages are typically hundreds of kV but rely on steady solar wind conditions on a time scale that is longer than typical at Jupiter's orbit. How the reconnection voltage compares to the voltage applied due to the “viscous‐like” interaction involving K‐H instability remains unclear.