Shape of the geomagnetic field solar wind boundary

Abstract

The shape of the boundary of the geomagnetic field in a solar wind has been calculated by a self‐consistent method in which, in first order, approximate magnetic fields are used to calculate a boundary surface. The electric currents in this boundary produce magnetic fields, which can be calculated once the first surface is known. These are added to the dipole field to give more accurate fields, which are then used to compute a new surface. This iterative procedure converges rapidly, and the final surface may be tested by finding how close the total fields outside the boundary are to the required value of zero. The result of this stringent test is that the magnetic fields in the plasma outside the fourth surface and within twice the distance to the boundary on the solar side are everywhere less than 1 per cent of the geomagnetic dipole field in the absence of a solar wind. This surface has been used to calculate the perturbation of the geomagnetic field by the solar wind; the results of these calculations, plus a number of applications, are given in an accompanying paper.

Magnetospheric equilibrium with anisotropic pressure

“…Eventually, our goal is to determine 'he outer magnetic flux surface (magnetopause) self-consistendy by considering all the major magnetospheric current systems outside Jte magnetopausc [Olson and Pfitzer, 1977]. The shape of the magnetopause will be determined iteratively as part of the equilibrium solution by a pressure balance between the magnetic field and a steady solar wind with the requirement that the normal component of the magnetic field vanish at the boundary [Mead and Beard, 1964]. Tue solid lines correspond to the equilibrium solution, and the dotted lines represent the dipolc magnetic flux surfaces.…”

“…Therefore, to reduce the computational domain and to avoid the singularity at r = 0, we will consider a computational domain bounded by (a) an outer boundary with flux vp out and with shape to be specified, (b) an inner boundary with contribution due to dipole magnetic flux and IMF flux, and (c) boundary curves on the earth's surface between y jn and y &It curves. The choice of the outer boundary will take in account the effect of the solar wind [Mead and Beard, 1964;Toffoletto and Hill, 1986;Voigt, 1981Voigt, ,1986b.…”

External Aerodynamics of the Magnetosphere

“…An e v a l u a t i o n of t h e accuracy of t h e r e s u l t s determined through u s e of t h e approximation o u t l i n e d i n f i g u r e 1 3 can b e gained by comparison with t h e h i g h e r o r d e r approximations t o t h e e x a c t Chapman-Ferraro problem given by Midgley and Davis (1963) and Mead and Beard (1964) f o r t h e shape o f t h e e n t i r e magnetosphere boundary f o r A = 0 . Such a comparison i s p r e s e n t e d i n f i gu r e 19 of t h e r e s u l t s f o r t h e e q u a t o r i a l and p r i n c i p a l meridian p l a n e s .…”

Adiabatic motion of outer-zone particles in a model of the geoelectric and geomagnetic fields

“…Theoretical calculations of the e f f e c t of t h e solar wind on t h e e a r t h ' s magnetic f i e l d have been presented by many authors [ S p r e i t e r and Briggs, 1962; Midgley and Davis, 1963; Mead and Beard, 1964;Mead, 1964; Axford e t a l . , 19641.…”