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Electron density in the cusp ionosphere: increase or depletion?
Author(s) -
Pitout Frédéric,
Blelly PierreLouis
Publication year - 2003
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 - 10.1029/2003gl017151
Subject(s) - electron precipitation , ionosphere , electron , electric field , cusp (singularity) , magnetosheath , geophysics , physics , electron density , population , ion , atmospheric sciences , computational physics , atomic physics , magnetosphere , plasma , magnetopause , nuclear physics , geometry , mathematics , demography , quantum mechanics , sociology
Radar observations indicate that the electron density may decrease significantly in the cusp ionosphere, despite the intense precipitation of low‐energy electrons originating from the magnetosheath. We have modeled the ionospheric footprints of the cusp and mantle regions, and we focus on the two rival processes acting pro and con the electron density build‐up in those regions of intense precipitation, which also happened to be regions of strong electric field. On one hand, the precipitation provides the ionosphere with electrons; on the other hand, the strong electric field heats up the ion population, stimulating the production of NO + . A fraction of the NO + produced then feeds the electron‐consuming chemical reaction NO + + e − → NO in the F1‐region, although this reaction is not favored in presence of a high electron temperature. We investigate various combinations of E‐field and initial electron densities. Our simulations clearly show that the overall result depends on the origin of the flux tube, which eventually opens in the cusp region. We interpret our results in terms of seasonal effects, IMF‐B y and MLT dependence.