Wave-driven fluctuations in OH nightglow from an extended source region

Journal Article · Thu Sep 01 04:00:00 EDT 1988 · Journal of Geophysical Research; (United States)

DOI:https://doi.org/10.1029/JA093iA09p09903· OSTI ID:5940870

Schubert, G; Walterscheid, R L ^[1]

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1. Aerospace Corp., Los Angeles, CA (United States)

Hydroxyl nightglow emissions arise from a region of the atmosphere several to 10 km thick centered at about the mesopause. The intensity of the nightglow is therefore a superposition of contributions from individual thin emitting layers. The inferred rotational temperature is an intensity weighted average of the temperatures throughout the emitting region provided that the overall temperature variation of the region is small compared with the average temperature, and that the Boltzmann exponent in the rotational line intensity distribution is not much larger than unity. Acoustic-gravity waves propagating through the emitting region produce fluctuations in the OH nightglow; intensity and temperature oscillations, <{delta}I> and <{delta}T>, are conveniently related by the ratio <{eta}> = (<{delta}I>/<{bar I}>)/(<{delta}T{sub 1}>/<{bar T}{sub 1}>), where the overbar refers to time-averaged quantities. When the vertical wavelength {lambda}{sub {upsilon}} of a disturbance is large compared to the vertical thickness of the emitting region, <{eta}> is accurately given by {eta} = ({delta}I/{bar I})/({delta}T/{bar T}) for a thin layer at the peak emission height. However, when {lambda}{sub {upsilon}} is comparable to or smaller than the emission region thickness, <{eta}> values can vary widely from the peak emission height ratio {eta}. When {lambda}{sub {upsilon}} is small, the magnitude of the normalized fluctuation in net intensity {vert bar} <{delta}I>/<{bar I}> {vert bar} is considerably reduced from the large {lambda}{sub {upsilon}} value due to cancellation effects of out-of-phase layers in the emitting region. Therefore, there is an observational bias toward detection of nightglow fluctuations from waves with {lambda}{sub {upsilon}} greater than emission region thickness.

• OSTI ID: 5940870
• Journal Information: Journal of Geophysical Research; (United States), Journal Name: Journal of Geophysical Research; (United States) Vol. 93:A9; ISSN 0148-0227; ISSN JGREA
• Country of Publication: United States
• Language: English

Related Subjects

661320* -- Auroral
Ionospheric
&amp; Magnetospheric Phenomena-- (1992-)
71 CLASSICAL AND QUANTUM MECHANICS
GENERAL PHYSICS
AIRGLOW
COMPARATIVE EVALUATIONS
EARTH ATMOSPHERE
EMISSION SPECTRA
EVALUATION
FLUCTUATIONS
GRAVITY WAVES
HYDROXYL RADICALS
MESOSPHERE
RADICALS
SPECTRA
TEMPERATURE DISTRIBUTION
VARIATIONS
WAVE PROPAGATION