McIntosh Archive (McA): Four Cycles of Solar Synoptic Maps

New: updated maps! All of SC23, and many from SC21 and SC22 now processed.

In 1964, Patrick McIntosh, a scientist at NOAA’s Space Environment Center in Boulder, began creating hand-drawn synoptic maps of solar magnetic features. In all, he compiled ~45 years or nearly four complete solar sunspot cycles of maps, representing a unique record of the large-scale organization and variation of the Sun’s magnetic field. Pat recently passed away, and his archive was in danger of being lost. Although versions of the maps were archived in scanned format at the NOAA National Centers for Environmental Information (NCEI), many maps only existed in hard-copy format in boxes, and none of the scanned maps possessed metadata allowing digital search and analysis.

Example of original, hand-drawn McIntosh Archive (McA) synoptic solar map -- vertical axis is solar latitude (from South to North pole) and horizontal axis is solar longitude (representing one solar Carrington rotation of approximately 27 days).

The map after processing. Magnetic features are identified with a distinct color, as described in legend.

The intent of the McIntosh Archive (McA) project (a Boston College/NOAA/NCAR collaboration, funded by the NSF) has been first and foremost to preserve the archive in its entirety, by completing the scanning of all of the maps; this has been achieved. Beyond this, a procedure has been designed and implemented to standardize the size and orientation of the digital maps, to remove any unnecessary notes, marks or symbols, and to colorize the maps so that each magnetic feature is uniquely searchable. To date, final versions of most maps between 1981 and 1991, a few between 1991 and 1996, and all of the maps between 1996 and 2009 have been archived at NOAA/NCEI.