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The source population for the cusp and cleft/LLBL for southward IMF
Author(s) -
Fuselier S. A.,
Lockwood M.,
Onsager T. G.,
Peterson W. K.
Publication year - 1999
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 - 10.1029/1999gl900354
Subject(s) - magnetosheath , magnetosphere , magnetopause , cusp (singularity) , physics , plasma , interplanetary magnetic field , geophysics , plasma sheet , population , solar wind , convection , space physics , mechanics , geometry , mathematics , demography , quantum mechanics , sociology
The distinction between plasma properties in different dayside regions in the Earth's magnetosphere is of strong interest as it is often indicative of specific physical processes. This is certainly true for the distinction between low latitude boundary layer (LLBL) and cusp plasma, which has been attributed to the effects of plasma diffusion across the magnetopause (LLBL) versus a more direct entry of magnetosheath plasma (cusp). It is also the case, however, that quite different plasma regions can result more simply from a common source plasma, and from different stages of temporal evolution of the plasma associated with magnetospheric convection. In this paper, we show that, for southward interplanetary magnetic field (IMF) conditions, the distinction between the cusp and cleft/LLBL at low altitudes may result from the single process of magnetosheath plasma entry into the magnetosphere on reconnected field lines. The different plasma characteristics of the two regions result from the properties of the source magnetosheath ion distribution and the effects of magnetic reconnection. Using well known properties of the magnetosheath, several predictions concerning the cusp and cleft/LLBL precipitation are readily derived.