INTERPLANETARY FIELD AND GEOMAGNETIC VARIATIONS - A UNIFIED VIEW

The relationship between interplanetary magnetic fields seen by the Ames magnetometer on board Explorer 33 and surface magnetic variations has been studied. The emphasis of the study is toward achieving a unified view of all the experimental results, both of this study and previous studies. Various statistical studies of the relationship between Kp and parameters of the solar wind were carried out. The effect of the direction of the z component of the interplanetary field is confirmed. In all other statistical studies the data were divided into two groups, one in which the 3-hr average field pointed northward, and the other in which it pointed southward. In this way, we show, for example, that the tendency toward an association of high Kp with intense interplanetary fields is independent of the North-South effect. Other statistical investigations were also carried out. The Sun was considerably disturbed during the period covered by this study, giving an excellent opportunity to observe the magnetic configuration of flare-induced interplanetary storms and their relation to geomagnetic storms. The interplanetary storm was found to be typified by persistent, strong fields (up to 30 γ) that rise far out of the ecliptic plane. As discussed below, this is to be expected on the basis of simple models. Further, it was found that high-velocity plasma and intense, highly disturbed interplanetary fields are also typical of interplanetary storms. The close association of these parameters in the interplanetary medium is one cause of confusion in interpretations of geomagnetic studies. During the flare-produced storm of February 15, 1967, there was a remarkably close temporal association between events in space and on the surface. This event is discussed in detail. © 1969.