PROGRESS IN MAGNETOSPHERIC RADIO

Since the last report was written (in the spring of 1966), there has been a remarkable advance in our knowledge and understanding of the structure and behavior of the magnetosphere, especially with regard to the fundamental problems of the aurora and geomagnetic storms. The average structure of the quiet magnetosphere has been studied in considerable detail [Ness et al., 1966; Spieser and Ness, 1967; Behannon, 1968; Fairfield, 1968; Mihalov et al., 1968], and it has been shown that the tail and ‘neutral’ sheet extend well past the moon, and possibly to much greater distances [Ness et al., 1967]. The nature of the changes that occur in the geomagnetic field during disturbed periods has been observed, especially by magnetometers on the geostationary satellite ATS 1 [Brown et al., 1968; Cummings et al., 1968; Cummings and Coleman, 1968]. It has been found that the ring current, which is usually situated between 3 and about 10 RE depending on the degree of geomagnetic activity, commonly has a pronounced asymmetric component, with the maximum inflation of the geomagnetic field occurring in the evening sector. Copyright 1969 by the American Geophysical Union.