Evolution of the Global Solar Magnetic Field over 4 Solar Cycles: Use of the McIntosh Archive

Thursday, July 26, 2018

The McIntosh Archive consists of a set of hand-drawn solar Carrington maps created by Patrick McIntosh from 1964 to 2009. McIntosh used mainly H, He-I 10830Å and photospheric magnetic measurements from both ground-based and NASA satellite observations.

Butterfly-type plots of all of the McA data processed to date
Butterfly-type plots of all of the McA data processed to date starting with CR 1513 in October 1966 and ending with CR 2086 in July 2009. The Year scale is at the top and the CR scale at the bottom. This plots for each CR all sunspots (orange), the poleward-most filament boundaries (green), and the poleward-most CH boundaries (red and blue). As in Figure 6a, circles (diamonds) indicate the most northward (southward) extensions of CH boundaries for each CR, and red and blue indicate magnetic polarity.

With these he traced polarity inversion lines (PILs), filaments, sunspots and plage and, later, coronal holes, yielding a unique ~45-year record, over four complete solar cycles, of synoptic maps of features associated with the large-scale organization of the solar magnetic field. We first discuss how these and similar maps have been used in the past to investigate long-term solar variability. Then we describe our work in preserving and digitizing this archive, developing a digital, searchable format, and creating a website and an archival repository at NOAA’s National Centers for Environmental Information (NCEI). Next we show examples of how the data base can be utilized for scientific applications. Finally, we present some preliminary results on the solar-cycle evolution of the solar magnetic field, including the polar field reversal process, the evolution of active longitudes, and the role of differential solar rotation.

Publication Name: Frontiers in Space Sciences

First HAO Author's Name: Sarah Gibson

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