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Critical comparison of OII(732–733 nm), OI(630 nm), and N 2 (1PG) emissions in auroral rays
Author(s) -
Semeter Joshua
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 - 10.1029/2002gl015828
Subject(s) - ionosphere , altitude (triangle) , atomic oxygen , airglow , excited state , sky , atmospheric sciences , atomic physics , physics , emission spectrum , night sky , astrophysics , analytical chemistry (journal) , materials science , oxygen , spectral line , chemistry , geophysics , astronomy , chromatography , geometry , mathematics , quantum mechanics
All‐sky spectral imagery has been used to study the altitude distribution of OII(732–733 nm), OI(630 nm), and N 2 (1PG) emissions in tall auroral rays appearing at the poleward edge of the auroral oval. The OII(732–733 nm) emission layer was consistently higher than the OI(630 nm) emission layer in these structures; the peak emission altitudes were estimated to be ∼380 km and ∼240 km, respectively. Neither the high absolute altitude of the OII(732–733 nm) peak nor its >100 km offset from the OI(630 nm) peak are consistent with published model results, which consider electron impact on atomic oxygen as the sole source of auroral O + ( 2 P ). The present results suggest that O + ( 2 P ) may also be excited directly from ambient ionospheric O + ( 4 S ) atoms. Other contributing factors may include a significant underestimation of the rate coefficients for O + ( 2 P ) quenching, or field‐aligned up‐flows of ionospheric O + .