Excess open solar magnetic flux from satellite data:1. Analysis of the third perihelion Ulysses pass

摘要

We use the third perihelion pass by the Ulysses spacecraft to illustrate and investigatethe "flux excess" effect, whereby open solar flux estimates from spacecraft increasewith increasing heliocentric distance. We analyze the potential effects of small-scalestructure in the heliospheric field (giving fluctuations in the radial component on timescalessmaller than 1 h) and kinematic time-of-flight effects of longitudinal structure in thesolar wind flow. We show that the flux excess is explained by neither very small-scalestructure (timescales 1 day) solar wind speed variations on the frozen-in heliospheric field. Weshow that averaging over an interval T (that is long enough to eliminate structureoriginating in the heliosphere yet small enough to avoid cancelling opposite polarity radialfield that originates from genuine sector structure in the coronal source field) is only anapproximately valid way of allowing for these effects and does not adequately explain oraccount for differences between the streamer belt and the polar coronal holes.