Beyond sunspots: Studies using the McIntosh Archive of global solar magnetic

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Thursday, December 15, 2016

In 1964 (Solar Cycle 20; SC 20), Patrick McIntosh began creating hand-drawn synoptic maps of solar magnetic features, based on H-alpha images. These synoptic maps were unique in that they traced magnetic polarity inversion lines, and connected widely separated filaments, fibril patterns, and plage corridors to reveal the large-scale organization of the solar magnetic field.

Open vs. closed magnetic field evolution over Solar Cycle 23 image
Open vs. closed magnetic field evolution over Solar Cycle 23 based on McIntosh archive synoptic maps. Classic butterfly diagram of sunspots (orange) overlaid with most poleward filament per Carrington rotation (CROT; green), showing “rush to the poles”, and coronal hole boundaries (red=negative, blue=positive; furthest north per CROT=circles, furthest south=diamonds), showing evolution of both polar and a low-latitude coronal holes.

Coronal hole boundaries were later added to the maps, which were produced, more or less continuously, into 2009 (i.e., the start of SC 24). The result was a record of ~45 years (~570 Carrington rotations), or nearly four complete solar cycles of synoptic maps. We are currently scanning, digitizing and archiving these maps, with the final, searchable versions publicly available at NOAA's National Center for Environmental Information. In this paper we present preliminary scientific studies using the archived maps from SC 23. We show the global evolution of closed magnetic structures (e.g., sunspots, plage, and filaments) in relation to open magnetic structures (e.g., coronal holes), and examine how both relate to the shifting patterns of large-scale positive and negative polarity regions.