Observations of gravity wave propagation in the OI (557.7 nm), Na (589.2 nm) and the near infrared OH nightglow emissions

The observable effects of gravity waves on airglow emissions

WINDII, the Wind Imaging Interferometer on the Upper Atmosphere Research Satellite, began atmospheric observations on September 28, 1991 and since then has been collecting data on winds, temperatures and emissions rates from atomic, molecular and ionized oxygen species, as well as hydroxyl. The validation of winds and temperatures is not yet complete, and scientific interpretation has barely begun, but the dominant characteristic of these data so far is the remarkable structure in the emission rate from the excited species produced by the recombination of atomic oxygen. The latitudinal and temporal variability has been noted before by many others. In this preliminary report on WINDII results we draw attention to the dramatic longitudinal variations of planetary wave character in atomic oxygen concentration, as reflected in the OI 557.7 nm emission, and to similar variations seen in the Meinel hydroxyl band emission.

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Longitudinal structure in atomic oxygen concentrations observed with WINDII on UARS

The theory of Hines and Tarasick (1987) for the effects of gravity waves on airglow emissions is extended to consider more complex airglow chemistries, including multiple and mutiple-step production mechanisms, quenching, and other loss processes. Attention is given to nonsteady state chemistry, since the time constants of some species involved in OH* production are comparable with gravity wave periods. Relations for the dependence of η, the ratio of brightness to temperature fluctuations, on emission chemistry are presented in a generalized form which is readily applicable to other emissions. The specific case of OH airglow is examined in detail for the quenching rates of Llewellyn et al. (1978) and for those of Lowe (1991). Quenching is found to be important to predictions of η The results obtained are compared with the limited set of published observations of gravity waves in OH airglow. Although the theory predicts significant differences in the behavior of η for the two sets of rates, the existing data are not adequate to draw firm conclusions.

Effects of gravity waves on complex airglow chemistries: 2. OH emission

Longitudinal structure in atomic oxygen concentrations observed with WINDII on UARS. [Wind Imaging Interferometer]

We provide evidence of the influence of planetary waves on the intensity variations of the 557.7-nm airglow emission. The comparison relies on simultaneous measurements at four different stations located between 37°N and 56°N in latitude, 36°E and 3°W in longitude: meteor wind observations in France and USSR and optical measurements at 557.7 nm in France and Spain, in July 1971. An oscillation of period near 2 days had been identified in the wind data; it is also apparent on the nightglow intensity variations. Its characteristics are well accounted for by the first symmetric mode of the 52- hour period planetary oscillation of horizontal wave number 3, described previously (Glass et al., 1975). A 4±1 hour period gravity wave apparently present in the data of the French stations is discussed.

M. Massebeuf

Papers

Simultaneous measurements of meteor winds and green line intensity variations: Gravity waves and planetary waves