Solar Terrestrial Relationships

Abstract

The identification of moderate geomagnetic activity with various solar regions has been discussed in the light of the long sequences of annual variation (30 to -50 solar rotations) obtained from the analysis of geomagnetic activity of the low sunspot activity periods 1920-24, 1930-34, 1940-44 (no long sequences) and 1950-54 and solar axial hypothesis. On the basis of these identifications it is shown that the geomagnetic activity can broadly be grouped in three heads-(l) Intense geomagnetic storms, (2) disturbed M -storms and (3) quiet M-storms.

         Various features of these geomagnetic storms are qualitatively explained from the focussing of solar-ion streams taking account of the local and general solar a It is found that the streams emerging from the solar regions of large magnetic field may get dispersed, while they may come out in the form of concentrated streams from quiet solar regions which do not possess large magnetic fields. Further qualitative explanation for the formation of coronal plumes near the Sunspots and of coronal streamers around the sunspot minima have also been given.