Characteristics of solar flare particle increases during recovery of Forbush decreases with reference to 7 May 1978 event

Sudden increase of cosmic ray intensity registered mainly by ground based detectors is due to high energy particles of solar origin. These are generated on rare occasions during intense solar flares. Out of 30 ground level enhancements observed so far, the increase of intensity on 7 May 1978 is the largest in this and earlier solar cycles and has peculiar characteristics which are reported along with similar events observed earlier. It is found that the intensity increase is highly anisotropic with the maximum increase being registered by the European stations. The event occurred during the late recovery phase of a large and long lasting Forbush decrease and hence it is quite likely to have better channeling effect in guiding the particles along the interplanetary magnetic field lines from the sun, producing large anisotropy. The characteristic features of the past events occurring during late recovery of Forbush decreases, but in different phases of solar activity, are not very different from one another. From this it is concluded that the near earth region is not dominant in producing the modulation of cosmic rays. (auth.)