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Is diffuse aurora driven from above or below?
Author(s) -
Khazanov G. V.,
Sibeck D. G.,
Zesta E.
Publication year - 2017
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 - 10.1002/2016gl072063
Subject(s) - magnetosphere , physics , ionosphere , electron , atmosphere (unit) , ionization , plasma , plasma sheet , atomic physics , flux (metallurgy) , electron precipitation , geophysics , computational physics , ion , materials science , nuclear physics , meteorology , quantum mechanics , metallurgy
In the diffuse aurora, magnetospheric electrons, initially precipitated from the inner plasma sheet via wave‐particle interaction processes, degrade in the atmosphere toward lower energies, and produce secondary electrons via impact ionization of the neutral atmosphere. These initially precipitating electrons of magnetospheric origin can also be additionally reflected back into the magnetosphere, leading to a series of multiple reflections by the two magnetically conjugate atmospheres that can greatly impact the initially precipitating flux at the upper ionospheric boundary (700–800 km). The resultant population of secondary and primary electrons cascades toward lower energies and escape back to the magnetosphere. Escaping upward electrons traveling from the ionosphere can be trapped in the magnetosphere, as they travel inside the loss cone, via Coulomb collisions with the cold plasma, or by interactions with various plasma waves. Even though this scenario is intuitively transparent, this magnetosphere‐ionosphere coupling element is not considered in any of the existing diffuse aurora research. Nevertheless, as we demonstrate in this letter, this process has the potential to dramatically affect the formation of electron precipitated fluxes in the regions of diffuse auroras.