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The OI844.6 nm emission in evening twilight
Author(s) -
BahsounHamade F.,
Wiens R. H.,
Shepherd G. G.
Publication year - 1989
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/gl016i012p01449
Subject(s) - twilight , zenith , radiance , solar zenith angle , solar telescope , azimuth , aeronomy , airglow , environmental science , physics , flux (metallurgy) , atmospheric sciences , optics , remote sensing , materials science , atmosphere (unit) , astronomy , meteorology , telescope , geology , metallurgy
Ground‐based measurements of the atomic oxygen multiplet emission at 844.6nm were made during evening twilight through the fall and winter of 1988/89, from Toronto using a low‐resolution Fabry‐Perot interferometer. Observations were made in the azimuth of the sun at 20° above the horizon, over a local solar zenith angle range from 94° to 99°. The radiance variation as a function of SZA is presented, with correction for atmospheric extinction. These are the first ground based measurements of the 844.6 nm emission ever reported for early twilight. The measurements are an important first step in obtaining the atomic oxygen density as well as the ratio of the integrated photoelectron flux to the solar EUV flux. The results are compared with previous measurements by others.