Abstract:
The amplitudes of geomagnetic sudden commencements are examined in ion to the optical, energetic particle and radio characteristics of source flares. It has been shown that all sudden commencements of amplitude above a threshold minimum at a given middle latitude station are associated with energetic particle events. East-west asymmetry and centre-limb variation in propagation times of storm plasma have also been examined. The day-time enhancement of SC amplitudes in the equatorial regions has been briefly discussed. The SC amplitude characteristics have been utilized to identify about 50 solar proton events during sunspot cycles 12–18.
