Digital Solar Synoptic Charts

derived from observations in H-alpha 6563Å and HeI 10830Å

H-alpha solar synoptic charts are now available in digital format for the period 1966-1987, permitting quantitative analyses and specialized displays for solar-terrestrial research. These data are unique in having coronal holes mapped in context with large-scale magnetic fields for the full period of HeI 10830Å observations (1975-1987).

H-alpha synoptic charts map the complete patterns of lines of polarity inversion (neutral lines) inferred from the positions of filaments and other chromospheric structures whose form and presence are governed by magnetic fields. The H-alpha charts are complementary to magnetograms by emphasizing positions of visible structures where magnetograms have little signal. The H-alpha neutral lines form coherent and persistent features with a detailed correspondence to coronal structures.

The charts have been regularly compiled by McIntosh at the Space Environment Laboratory (SEL) of the National Oceanic and Atmospheric Administration in Boulder, Colorado, and published monthly in Solar-Geophysical Data since 1973. Coronal Holes inferred from HeI 10830Å observations first appeared on charts published in 1981. Digital versions of the charts were made in 1989 by McIntosh and his co-workers at SEL and by Suess at the NASA Marshall Space Flight Center. These were then validated and further processed at IPS Radio and Space Services in Australia by Willock and Thompson.

The digital charts encode magnetic-field polarity and coronal hole polarity with four distinctive gray levels. The data are in the form of a single digital chart for each Carrington Rotation (CR) of 27.28 days from CR1512 (September 1966) through CR1796 (December 1987). Each pixel represents one square heliographic degree.

An atlas of "stackplots" based on latitude zones of these digital charts has been published by McIntosh, Willock and Thompson in UAG Report 101. These displays show long lifetimes to large-scale features and reveal proper motions, evolutions and rotation rates with clarity.

Data are available on 3½ inch or 5¼ inch IBM-compatible diskettes. Diskette contains data description and comprehensive tables of rotation numbers, start and end times, and data availability dates. Data are in numeric format. For non-programmers we can also supply TIFF, PCX, or GIF ect., plotted files. Click for ordering information.

Data Contributors:

P.S. McIntosh, NOAA Space Environment Laboratory, 325 Broadway, Boulder, CO 80305 USA

E.C. Willock and R.J. Thompson, IPS Radio and Space Services, PO Box 5606, West Chatswood, NSW 2057, Australia

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