Structure of the Heliospheric Current Sheet in the Early Portion of Sunspot Cycle 21,

The structure of the heliospheric current sheet on a spherical source surface of radius 2.35 R has been computed using a potential field model during the first year and a half after the last sunspot minimum. The solar polar magnetic field that is not fully observed in conventional magnetograph scans was included in the computation. The computed heliospheric current sheet had a quasi-stationary structure consisting of two northward and two southward maxima in latitude per solar rotation. The extent in latitude slowly increased from about 15 degrees near the start of the interval to about 45 degrees near the end of the interval. The magnetic field polarity away from the Sun or toward the Sun at the subterrestrial latitude on the source surface agreed with the interplanetary magnetic field polarity observed or inferred at Earth on 82 of the days. The interplanetary field structure observed at Earth at this time is finely tuned to the structure of low-latitude fields on the source surface. Author