Ozone in the mesosphere is determined from observations made by the near-infrared spectrometer experiment on the Solar Mesosphere Explorer satellite (SME) between 50 and 90 km over most latitudes at 3:00 P.M. local time. The spectrometer measures emission from O2(1Δg) at 1.27 μm that is primarily due to the photodissociation of ozone. The instrument consists of a parabolic telescope that limits the field of view to less than 0.1°, an Ebert-Fastie spectrometer, and a passively cooled lead sulfide detector system. The limb radiances, measured as the spacecraft spins, are inverted, producing volume emission rate profiles from which ozone densities are inferred. The vertical resolution is better than 3.5 km. The calculation of ozone accounts for quenching and atmospheric transmission of both solar radiation and 1.27-μm radiation. We have established the existence of a secondary maximum of ozone density near 80km. An error analysis shows that the effects of random errors in the data and in the analysis on the final ozone profile are less than 10% between 50 and 82 km.

Solar Mesosphere Explorer Near-Infrared Spectrometer: Measurements of 1.27-μm radiances and the inference of mesospheric ozone

A theory is given of electrical breakdown in air for non-uniform electric fields. It is proposed that space-charge effects tend to make the electric field in the streamer column uniform at a value of E/N for which effective ionization and attachment rates are equal (E is the electric field and N the gas number density). It is also proposed that a1 Delta g metastable states of molecular oxygen, produced in the pre-breakdown corona and streamer processes, have a dominant role in determining E/N in the streamer channel, because of their ability to detach electrons from O2- ions and thus reduce the effective attachment coefficient. Assuming an effective value of alpha /N=10-22 cm2 ( alpha being the ionization coefficient) at E/N=20 Td, predictions of breakdown fields in dry air and humid air are in fair agreement with experimental results for rod-rod breakdown with electrode spacings of from 0.5 m to 2.5 m. The effect of the metastables is to reduce the breakdown field applicable to plane parallel electrodes by a factor of about 6. It is predicted that 1% water vapour in air increases breakdown fields by about 11%. A breakdown criterion is derived defining the critical E/N for breakdown in terms of electron transport coefficients and metastable rate constants.

https://iopscience.iop.org/article/10.1088/0022-3727/25/2/012/pdf

Theory of electrical breakdown in air-the role of metastable oxygen molecules

An oxygen-hydrogen atmospheric model and its application to the OH emission problem

Photochemistry of the Martian atmosphere

The ozone densities between 50 and 90 km are deduced from 1.27 µm airglow measured on the Solar Mesosphere Explorer satellite. The derived densities agree well with those made simultaneously from SME by the ultraviolet spectrometer. The data set extends from pole to pole at about 3 pm, for most sunlit latitudes. At low altitudes, in the mesosphere, there are larger variations in ozone density in the winter latitudes than in the summer. Above the meso-pause the day-to-day variation in ozone density is a factor of two at most latitudes and times.

Ozone density distribution in the mesosphere (50‐90 km) measured by the SME limb scanning near infrared spectrometer

This paper reports determinations of collisional deactivation rate constants for O2(1Δg) by minor atmospheric constituents and other gases. The benzene–oxygen photochemical system was used to produce O2(1Δg), and relative concentrations were measured by monitoring the intensity of its emission at 1.27 μ. The rate constants for the reaction O2(1Δg)+M→O2+M were 4.53 × 10−18, 5.60 × 10−18, and (0.5–1.0) × 10−19 (cm3 molecule−1·sec−1) for M=H2, H2O, and N2O, respectively. Upper limits were obtained for deactivation by He, Ar, CO2, and SF6 of 8.0 × 10−21, 8.3 × 10−21, 1.5 × 10−20, and 1.2 × 10−20, respectively. The temperature dependence of the deactivation of O2(1Δg) by oxygen has been investigated. The rate constant can be expressed in the form kO2 = 2.22 ± 0.09 × 10−18 (T / 300)n, where n = 0.78 ± 0.32 and T is the temperature in degrees Kelvin.

F. D. Findlay

Papers

Collisional Deactivation of O2(1Δg)