Geomagnetic activity associated with earth passage of interplanetary shock disturbances and coronal mass ejections

Abstract

Coronal mass ejection events (CMEs) are important occasional sources of plasma and magnetic field in the solar wind at 1 AU, accounting for approximately 10% of all solar wind measurements in the ecliptic plane during the last solar activity maximum. Previous work indicates that virtually all transient shock wave disturbances in the solar wind are driven by fast CMEs. Using a recently appreciated capability for distinguishing CMEs in solar wind data in the form of counterstreaming solar wind electron events, this paper explores the overall effectiveness of shock wave disturbances and CMEs in general in stimulating geomagnetic activity. The study is confined to the interval from mid‐August 1978 through mid‐October 1982, spanning the last solar activity maximum, when ISEE 3 was in orbit about the L1 Lagrange point 220 Re upstream from Earth. We find that all but one of the 37 largest geomagnetic storms in that era were associated with Earth passage of CMEs and/or shock disturbances, with the large majority of these storms (27 out of 37) being associated with interplanetary events where Earth encountered both a shock and the CME driving the shock (shock/CME events). Although CMEs and/or shock disturbances were increasingly the cause of geomagnetic activity as the level of geomagnetic activity increased, many smaller geomagnetic disturbances were unrelated to these events. Further, approximately half of all CMEs and half of all shock disturbances encountered by Earth did not produce any substantial geomagnetic activity as measured by the planetary geomagnetic index Kp. The geomagnetic effectiveness of Earth directed CMEs and shock wave disturbances was directly related to the flow speed, the magnetic field magnitude, and the strength of the southward (GSM) field component associated with the events. The initial speed of a CME close to the Sun appears to be the most crucial factor in determining if an earthward directed event will be effective in exciting a large geomagnetic disturbance.

Characteristics of the interplanetary coronal mass ejections in the heliosphere between 0.3 and 5.4 AU

“…Solar wind structures which are the interplanetary counterparts of CMEs at the Sun [Gosling, 1990;Neugebauer and Goldstein, 1997] are now generally referred to as interplanetary coronal mass ejections (ICMEs). These ICMEs often trigger geomagnetic storms [Gosling et al, 1991], making them of great importance to space weather studies [Luhmann, 1997]. Thus much work has focused on ICME manifestations at 1 AU and their evolution in interplanetary space.…”

Merging of coronal and heliospheric numerical two‐dimensional MHD models

“…They are generally believed to be the ejecta of CMEs, and Burlaga et al [1982] called them magnetic clouds. Gosling et al [1991] estimated that approximately 30% of interplanetary CMEs have this form. The flux rope magnetic field can initiate geomagnetic activity if it contains fields that are southward relative to the magnetic field at Earth's magnetopause [Burlaga et al, 1987].…”

Probability of Solar Flares Turn out to Form a Coronal Mass Ejections Events due to the Characterization of Solar Radio Burst Type II and III

“…It is believed that closed magnetic field lines are stretched up to the interplanetary space, as confirmed by the counter streaming electron flux from the explosions [68]. It occurs from closed magnetic field regions, where magnetic free energy is stored and released during eruptions.…”