Solar Radio Bursts, Proton Events and Geomagnetic Activity
MARYLAND UNIV COLLEGE PARK DEPT OF PHYSICS AND ASTRONOMY
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The relationships between type II, type IV, microwave bursts and geomagnetic activity have been studied using data from various observatories compiled in the Solar-Geophysical Data over the period 1968-1982. It is found that type II bursts follow the trend of solar activity in general, more bursts occurring during periods of high solar activity. A similar trend is also seen with type IV bursts but their occurrence frequency is smaller than that of type II bursts. Superposed epoch analysis of geomagnetic activity index Ap before and after the events shows no dependence on type II bursts but the relationship with Ap improves following type IIIV bursts and a still better improvement is observed with type II bursts associated with moving type IV events. The position of type II burst on the solar disk does not seem to affect the Ap values significantly. Similar analysis carried out on the days of occurrence of solar proton events during 1970-1979 showed that an enhancement in Ap index on the secondthird day is clearly seen in some years but not in all. But on the average, Ap shows significant increase if we consider longer periods i.e. 5 to 10 years.