THE FLUX OF OPEN AND TOROIDAL INTERPLANETARY MAGNETIC FIELD AS A FUNCTION OF HELIOLATITUDE AND SOLAR CYCLE

We examine 45 years of near-Earth interplanetary observations as recorded in the National Space Science Data Center OMNI data set and 18 years of observations by the Ulysses spacecraft. We find that recent claims for a 50+ year low in interplanetary magnetic field intensity are substantiated, that the low flux levels can be attributed to open magnetic field lines, and that similar conditions existed in 1963-1964 during the start of the space age. Although the current solar minimum seems prolonged by recent standards and remarkably devoid of transient eruptions, we find no evidence that the present low inmagnetic field intensity can be traced to the low in transient ejection rates as measured by toroidal magnetic field levels. We also find that the flux of toroidal magnetic field is approximately zero at high latitudes as measured by the Ulysses spacecraft at all times including both solar minimum and solar maximum conditions. We likely attribute this to the subphotospheric azimuthal magnetic fields that arise due to differential rotation. Our analysis of toroidal flux rates compares favorably with computed estimates of axial flux ejection associated with coronal mass ejections and allows us to place an upper limit on the average latitudinal separation of the footpoints.