www.elsevier.nl/locate/planspasci Magnetohydrodynamic simulations of the e%ects of the solar wind on the Jovianmagnetosphere

We have used a three-dimensional magnetohydrodynamic simulation of the interaction between the solar wind and a rapidly rotating magnetosphere to study the e%ects of the solar wind dynamic pressure and the interplanetary magnetic 2eld (IMF) on the con2guration of the Jovian magnetosphere. Both the solar wind dynamic pressure and the IMF can cause substantial changes in the magnetosphere. On the dayside when the pressure increases the bow shock and magnetopause move toward Jupiter and the equatorial magnetic 2eld in the middle magnetosphere becomes more dipole-like. When the pressure decreases the boundaries move farther from Jupiter and the dayside magnetic 2eld becomes stretched out into a more tail-like con2guration. For northward IMF the boundaries move toward Jupiter but the 2eld becomes more tail-like. Finally, for southward IMF the boundaries move away and the 2eld becomes more dipole-like. These changes are qualitatively consistent with those observed on spacecraft passing through the dayside magnetosphere. However, we were not always able to get quantitative agreement. In particular the model does not reproduce the extremely tail-like magnetic 2eld observed during the Pioneer 10 and Ulysses inbound passes. The solar wind and IMF also in:uence the con2guration of the middle magnetosphere in the magnetotail. Tailward:ows were found in the nightside equatorial plasma sheet for most IMF orientations. Both inertial e%ects and the IMF in:uence reconnection in the tail. The only time the tailward:ow in the magnetotail stopped was during prolonged intervals with southward IMF. Then reconnection in the polar cusp caused the:ow to move out of the equatorial plane. c © 2001 Elsevier Science Ltd. All rights reserved. 1