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Time variations of the distant magnetotail
Author(s) -
Fairfield D. H.
Publication year - 1986
Publication title -
geophysical research letters
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 2.007
H-Index - 273
eISSN - 1944-8007
pISSN - 0094-8276
DOI - 10.1029/gl013i001p00080
Subject(s) - substorm , magnetosphere , physics , radius , flux (metallurgy) , polar , geophysics , interplanetary magnetic field , interplanetary spaceflight , earth radius , field line , solar wind , magnetic field , astronomy , materials science , computer security , quantum mechanics , computer science , metallurgy
The likely dimensions of an extended earth magnetotail are investigated by considering various published polar cap and magnetotail observations in light of recent knowledge about magnetosphere behavior under different interplanetary magnetic field conditions. It is argued that the magnetotail is highly‐time dependent. During southward field conditions the tail probably attains its maximum radius but is subject to "breaking off" via substorm associated reconnection events which temporarily deplete the flux and reduce the radius. During northward interplanetary conditions more field lines are apt to close near the earth leaving considerably less flux to form any extended tail. Using estimates for both the amount of open polar cap flux and the tail flux at 60 R e , we argue that at 200 R e either the tail cross section is elongated in the equatorial plane or the average radius is not more than 25 R e .