Abstract

We undertake a five solar-cycle (SC 19 - 23) approximate to 55-year (December 1954 to August 2009) study of the high latitude polarity inversion lines (PILs) using the recently digitized McIntosh Archive (McA) of solar synoptic (Carrington) maps. We looked at the evolution of the median solar lat... Show moreWe undertake a five solar-cycle (SC 19 - 23) approximate to 55-year (December 1954 to August 2009) study of the high latitude polarity inversion lines (PILs) using the recently digitized McIntosh Archive (McA) of solar synoptic (Carrington) maps. We looked at the evolution of the median solar latitudes of primary and secondary PILs, and of the polar coronal hole (CH) boundary for all 732 Carrington Rotations (CRs). We found hemispheric differences in the "Rush to the Poles" (RttP) where the polar CH gaps are often longer in the southern hemisphere (SH), and the secondary PIL reaches its polemost latitude at the end of its RttP later and more poleward than in the northern hemisphere (NH). The latitude oscillations found after this poleward peak are also stronger and often longer in the SH than in the NH, and exhibit a 22-year variation. The location variations in the CH boundaries and PILs appear to be at least partly associated with similar variations in the magnetic field. We also found equatorward expansions of the polar CHs by approximate to 50% and equatorward shifts in the PILs that were part of a disturbance that propagated approximate to 15 degrees/CR from the SH to the NH in the descending phase of SC 23. Show less