A resolution of the N[sub 2] Carroll-Yoshino (c4[prime] - X) band problem in the Earth's atmosphere
Journal Article
·
· Journal of Geophysical Research; (United States)
- Naval Research Lab., Washington, DC (United States)
- Johns Hopkins Univ., Baltimore, MD (United States)
In the study of UV airglow from the Earth's atmosphere, the N[sub 2] Carroll-Yoshino (CY) c4[prime][sup 1][Sigma][sup +][sub u] - X[sup 1][Sigma][sup +][sub g] (0,0) and (0,1) Rydberg band emissions near 958 [angstrom] and 980 [angstrom], respectively, are found to be weak relative to the c4[prime](0) excitation rate. This result is surprising because laboratory measurements show that CY(0,0) and CY(0,1) are the brightest N[sub 2] emission features between 910-1010 [angstrom] even under optically thick conditions. In order to investigate the cause of this weak emission quantitatively, the authors have developed a resonant fluorescent scattering model for CY(0,0) and CY(0,1). The model is intended to be comprehensive, including multiple scattering, extinction, branching, escape to space, predissociation, and temperature effects. Results show CY(0,0) photons are radiatively trapped and undergo resonance fluorescent scattering accompanied by substantial loss in the atmosphere. Indeed, the model predicts weak CY(0,0) intensities, consistent with observations. They find that the most important loss processes for the CY(0,v[close quotes]) system in the Earth's dayglow are predissociation and branching to CY(0,1) followed by absorption by the overlapping, 100% predissociated Birge-Hopfield I (BH I) b[sup 1][Pi][sub u](2) - X[sup 1][Sigma][sup +][sub g] (0) band. Near solar minimum, model CY(0,1) and (0,2) dayglow zenith intensities between 160-170 km range between 4-9 R and 0.5-1.5 R, respectively, where the lower number assumes 16.5% predissociation of the c4[prime](0) state and the higher number assumes 1% predissociation. These intensities are all consistent with observations reported by Morrison et al. 42 refs., 14 figs., 7 tabs.
- OSTI ID:
- 6711382
- Journal Information:
- Journal of Geophysical Research; (United States), Journal Name: Journal of Geophysical Research; (United States) Vol. 99:A1; ISSN JGREA2; ISSN 0148-0227
- Country of Publication:
- United States
- Language:
- English
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