Atmospheric Hydroxyl Research Articles

Time and altitude variations of vibrationally excited states of atmospheric hydroxyl

A time dependent one-dimensional theoretical model has been used to deduce averaged properties of the hydroxyl molecule airglow. Vertical profiles and time variations of the total amount of excited states have been established. The results are in close agreement with experimentally observed properties. Calculations have been made to examine the relative importance of the deactivation processes and to give limiting values to the adjustable coefficients. During the day, both collisional quenching and chemical deactivations are important, and reduce the emission by approximately the same factor while during the night collisional quenching seems to be negligible.

Inhomogeneities and wavelike variations of the rotational temperature of atmospheric hydroxyl

Quiet and disturbed variations of the rotational temperature of the hydroxyl emissions of the night sky in band 4-1 are described. Examples are given of wavelike propagation of the disturbances of rotational temperature.

Rocket-borne ultraviolet spectrometer measurement of OH resonance fluorescence with a diffusive transport model for mesospheric photochemistry

An upper limit on the column density of the hydroxyl radical in the earth's upper atmosphere was determined with a rocket-borne scanning spectrometer using resonance fluorescence techniques in the near ultraviolet. The (0–0) band of the A2Σ-X2Π transition at 3064 A was studied between 60 and 108 km under evening twilight conditions from Wallops Island, Virginia, on June 27, 1969. The solar zenith angle was 92°. Particular attention is given to the problem of determining the Rayleigh scattered background to allow an accurate determination of the column emission rate from the OH molecule. An emission rate factor calculation for OH is presented that considers the rotational structure of the molecule and the effect of absorption by OH in the solar atmosphere. By using this emission rate factor, the upper limit on the column density of OH is found to be 6×1012 cm−2 at 65 km, 3×1012 cm−2 at 75 km, and 7×1011 cm−2 at 85 km. The dissociation rate for water vapor was calculated by using a high-resolution analysis of the O2 absorption cross section. A significant amount of H2O dissociation was found to occur throughout the mesosphere down to the stratopause. A mesospheric oxygen-hydrogen model that includes diffusive transport of water vapor and the recalculated H2O dissociation rate is considered in order to interpret the experimental results. It is demonstrated that the upper limit on the hydroxyl column density requires the eddy diffusion coefficient to be less than 4×106 cm2/sec in the lower mesosphere. A model for the concentration of H, OH, HO2, and H2O in the mesosphere is presented that uses a water vapor mixing ratio of 5×10−6 at 50 km and an eddy diffusion coefficient of 1×10−6 cm2/sec.

Observation of the OH Day-glow

IN 1960 Noxon and Vallence Jones1 with the co-operation of the Canadian Armament Research and Development Establishment launched a balloon-borne spectrometer and observed bands of the Δv = 1 sequence of upper atmospheric hydroxyl emission for the first time. Since then several balloon flights have been made from the Canadian Ajmament Research and Development Establishment for photometric measurements of the night air-glow from 2 to 4µ. A description of the spectrometer used and the results of these flights will appear soon2.