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Detailed comparison is made between various types of geomagnetic storms, solar flare activity and coronal holes for the year 1977. The Comprehensive Flare Index (CFI), which quantifies x-ray, optical and radio emission, again proves to be an increasing reliable predictor (statistically) of flare-associated geomagnetic storms as the value of the CFI increases. Two sequences of recurrent geomagnetic storms could be associated with coronal holes extending below 30 deg heliographic latitude. The two most active regions of the year resulted in 'flare-sequential' storms in which a coronal hole (and related sequential storms) developed subsequent to the decay of flare production in an adjacent active region. (Author)

Solar and geophysical circumstances prior to the 34 principal geomagnetic storms in 1976 have been evaluated. In this year of sun spot minima, 21 of the storms were unambiguously classified as sequential. For 7 of the storms prior flares may have played a role. Six of the storms remain as 'problem' situations. The 3 most severe storms in 1976 were associated with the 3 flares in 1976 with Comprehensive Flare Indices or = 10. Inspection of plots of daily geomagnetic character figures suggest that at least 6 different sequences contributed to the geomagnetic disturbance in 1976. Relationships were sought between inferred coronal holes and the observed locations of significant centers of activity as the possible origins of the sequential storm particles. All of the major recurrent storm sequences in 1976 apparently had at their roots significant centers of activity that could have been near the perimeters of deduced associated coronal holes. The sequential storms occurred as the active regions were dying and continued long after all optical events of the active regions had disappeared. (Author), Sponsored in part by MIPR-FY71218000003.