Velocity Variations of an Equatorial Plume throughout a Jovian Year

Analysis of features in the Equatorial Zone of Jupiter has shown that the equatorial plume reported by Pioneer 10 has existed for an 11-yr interval. During this interval the plume has shown an acceleration which can be interpreted as a constant component of 3 × 10 ^-8 m/sec ² and a sinusoidal component which anticorrelates with the planetocentric declination of the Sun, D_S, and has an amplitude of -0.96 m/sec per degree change of D_S. The sinusoidal component has been interpreted in terms of solar heating. Throughout this interval of time the Equatorial Zone has appeared abnormally dark and has contained many dark projections along the northern edge. When the plume approaches to within 25 to 30° of these features they are deflected in the direction of motion of the plume and then dissipate or become obscured as the plume passes. After passage of the plume normal features are again observed.