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Optical signatures of some magnetospheric processes on the dayside
Author(s) -
Sivjee G. G.,
Romick G. J.,
Deehr C. S.
Publication year - 1982
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/gl009i006p00676
Subject(s) - magnetosheath , magnetopause , daytime , electron precipitation , physics , geophysics , cusp (singularity) , astrophysics , atmospheric sciences , intensity (physics) , magnetosphere , plasma , optics , geometry , mathematics , quantum mechanics
Ground‐based daytime photometric observations of auroral optical emissions from the cusp region over Longyearbyen (Λ = 75°N) Svalbard are used to illustrate spatial variations in the average energy of particles precipitating in this region. Absolute intensity measurements of daytime auroral OI [¹D → ³P] 6300A emission (indicative of low energy precipitating particles), along the Longyearbyen magnetic meridian generally show a broad (Λ ≈ 2.5° ± 1°) emission region centered, on the average, around Λ = 77° ± 1° N. A relatively confined emission region of higher [OI] 6300A intensity occurrs equatorward of and separated from the cusp; this region is normally associated with visually prominent, structured auroras. Observations of the auroral OII [²D → ²P] 7320A emission, indicative of higher energy precipitating particles, shows that it is weaker in the cusp compared to its intensity in the region of structured auroras. Enhancement of the [OII] 7320A emission maximizes near the equatorward edge of the cusp when compared to the position and extent of the broad [OI] 6300A emission region. These observations indicate higher energy electron precipitation at the equatorward edge of the cusp which might be expected from energization of magnetosheath particles by wave‐particle interactions at the magnetopause.