Interplanetary magnetic field control of the Venus magnetosheathfield and bow shock location

Abstract

Six Venus years of Pioneer Venus Orbiter (PVO) data are analyzed in a coordinate system which isolates magnetic effects. The field draping pattern features two lobes easily identifiable even in the near planet region. The magnetosheath magnetic magnitude has a hemispherical asymmetry controlled by the IMF orientation in a manner suggesting preferential ion pickup in one hemisphere. This result complements recent findings that the bow shock position is responsive to IMF direction. Examination of the ionopause position to evaluate ionospheric effects on the overall asymmetry of the Venus-solar wind interaction produces negative but not conclusive results.