F2-Region disturbances associated with major magnetic storms

Abstract

The development of the disturbance in the F2-region during the magnetic storm of 7 June 1958 has been studied in some detail using h m F2 and N m F2 data for a number of stations at middle and low latitudes. It is found that the most pronounced increases in layer height occurred during the development of the main phase of the magnetic storm, these increases taking place simultaneously over a latitude range greater than 70° in the American sector, and a longitude range of at least 100°. Simultaneous decreases in N m F2 occurred over a wide range of longitudes, probably 360°, at middle latitudes. These changes indicate that the onset of the F2-region disturbance extended over a very wide area. The subsequent disturbance in N m F2 at individual stations was dependent on the local time of onset of the disturbance, season and latitude. In particular, the forms of the disturbance at a pair of magnetically conjugate stations were very different. Comparisons of N m F2 data at this and other pairs of magnetically conjugate stations at middle latitudes have also shown that the F2-region effects of magnetic disturbances occurring during equinox periods can be very different at the ends of a tube of force. These results are discussed in terms of the importance of electrodynamic movements of ionization and the effects of atmospheric heating during magnetic storms.