A quantitative model for the potential resulting from reconnection with an arbitrary interplanetary magnetic field

Abstract

A three-dimensional model is utilized to derive the electrie potential induced across the magnetosphere by reconnection between the geomagnetic lield and an arbitrary interplanetary mugnetie field. AssumpLions [hat Lhe magnetosheath ffow is uniform and ihat reconncction is not Iimited by processes occurring at Lhe magnetopause are made so that Lhe model calculation provides an upper limit to Lhe magnetospheric potential produced by reconnection. The magnitude of Lhe polar cap ionospheric electric tield compuLed from this model is larger than that measured on bailoons by an average factor of about 3, and Lhe model reproduces Lhe temporal variations of Lhe experimental data. Some magnetospheric properties related to Lhe magnetopause reconnection une and potential are discussed as a tirst suggestion toward using the model in studies of relevant magnetospheric problems. The model potential induced across Lhe magnetosphere becomes less dependent on the direction of the inLerplaneLary magnetic lield as Lhe strength of às transverse componeni increases. Thus a reduced correlation heiwcen magnetospheric phenomena and Lhe southward component of Lhe interplanetarN lield should exisi when the Lransverse interplanetary field component exceeds about 8 ,y. Observed dependences oU Lhe polar cap ionospheric current system on B. are explained by Lhe model, and similar variations with B x are predictcd. Graphs oU Lhe model potential as functioris of Lhe interplanetary magnetic iield components are given as an aid in its application to other problems.Considerable evidence nas accumulated to suggest that many features of magnetospheric dynamics are controlled by the interaction between the interplanetary and terrestrial magnetic tields. Dungey [1961] suggested that the mechanism responsible for this interaction is magnetic field reconoection taking place at the magnetopause, where the two fields meet. Thc general properties of this interaction are a change in Lhe topology of Lhe reconnecting fields and magnetic energy conversion into thermal and bulk energies of the plasma LDungey, 1953: Sweei, 1958Parker, 1963; Peischek, 1964; Yeh andAxford, 1970; Sonnerup, 19721. Direct evidence for reconnection between the geomagnetic and interpianetary lields arises from observations of energetic solar particles. The first results of this nature were described by Lin and Anderson [1966], and a recent review of subsequent observations has been presented by Morfihi and Schoier [1973]. Further experimental evidence has been obtained through correlations of geomagnetic disturbance aL ground levei with the southward component of Lhe interplanetary magnetic field [Fairfieid and Cahill, 1966; Rosioker and Faiihammar, 1967: Schaiien andWilcox, 1967; Nishida, 1968; Arno/dy. 1971], through ground magnetometer correlations with Lhe azimuthal component of the interplanetary magnetic field [Svaigaard. 1968;Mansurov, 1969; Friis-Chris:ensen et ai. 1972; Berihelier and Guerin, 19721, through studies of sateilite measurements of the tail magnetic fie...

X lines in the magnetotail for southward and northward IMF conditions

“…Magnetic reconnection developed with the appearance of an X line at the magnetopause, and the magnetotail governs the main mass and energy transport process in the solar wind-magnetosphere coupling system [Dungey, 1961;Gonzalez and Mozer, 1974;Akasofu, 1981;Wygant et al, 1983;Wang and Bhattacharjee, 1996;Wang et al, 2014]. At the magnetopause, the location of the X line highly depends on the orientations of the interplanetary magnetic fields (IMF).…”

Probing the boundary between antiparallel and component reconnection during southward interplanetary magnetic field conditions

“…[4] An alternative to antiparallel reconnection is the component reconnection tilted X-line model for southward IMF conditions [e.g., Sonnerup, 1970;Gonzalez and Mozer, 1974;Cowley and Owen, 1989;Moore et al, 2002]. This model predicts that reconnection occurs at the subsolar point where the solar wind plasma makes first contact with the magnetopause and then extends continuously along the dayside magnetopause regardless of the magnitude of the IMF B Y component.…”

Multi-site observations of the association between aurora and plasma convection in the cusp/polar cap during a southeastward(<i>B<sub>y</sub></i> <u>~</u> |<i>B<sub>z</sub></i>|) IMF orientation

“…One view is that reconnection in such cases can occur where there are antiparallel components in the external magnetosheath magnetic field and the Earth's field (Gonzalez and Mozer, 1974;Cowley, 1981;Sonnerup, 1984;Taguchi et al, 1993;Kawano and Russell, 1997;Siscoe et al, 2001). According to this view, reconnection can take place over large areas of the dayside magnetopause, for example, along a tilted reconnection line traversing the subsolar region and extending to high latitudes in both hemispheres.…”