Diurnal variation in Jovian subsolar magnetopause position

Abstract

The calculation of the idealized Jovian magnetosphere surface and magnetic fields arising from surface currents has been published (Engle, 1991). That calculation assumed the axis of all the interior sources of magnetic field to be perpendicular to the planet's orbital plane and hence to the incident solar wind. The rotation axis of Jupiter makes a small angle (3.13°) with its orbital plane; the magnetic axis is aligned approximately 10° with respect to the planet's rotation axis. The consequences are that the magnetic axis will precess about the planetary rotation axis during each diurnal rotation of period 9 hours and 55 min. The goal of the present work was to calculate the primary effects of this diurnal motion. In this paper are presented the results of calculations which have yielded global magnetopause models with the interior sources' axis tilted ±10° (in the noon‐midnight plane) with respect to the normal to the “plane” of the incident solar wind (which is here approximated to be coincident with the planet's equatorial plane). The consequential diurnally cyclical range in predicted dynamically stable magnetopause positions in the neighborhood of the subsolar point is reported. The magnetic fields arising from the magnetohydrodynamically stable currents on the magnetopause have been calculated. Convenient expressions for those fields' total contributions for points in the inner magnetosphere are included.