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  • 1
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    A model study of the response of mesospheric ozone to short-term solar ultraviolet flux variations (1990)
    In:  Other Sources
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    Publication Date: 2011-08-19
    Description: An investigation is conducted in order to determine the relative importance of several modeled processes in controlling the magnitude and phase of the mesospheric ozone response. A detailed one-dimensional modeling study of the mesospheric ozone response to solar UV flux variations is conducted to remove some of the deficiencies in previous studies. This study is also used to examine specifically the importance of solar zenith angle, self-consistent calculation of water vapor abundance, and temperature feedback with a nonlocal thermodynamic equilibrium radiation model. The photochemical model is described, and the assumptions made for the purpose of comparing model results with the observed ozone response obtained from a statistical analysis of Solar Mesosphere Explorer data (Keating et al., 1987) are discussed. The numerical results for the theoretical ozone response are presented. The results of selected time-dependent calculations are considered to illustrate the degree to which a relatively simple model of the mesosphere is able to capture the major characteristics of the observed response.
    Keywords: GEOPHYSICS
    Type: Journal of Geophysical Research (ISSN 0148-0227); 95; 22523-22
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  • 2
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    Vertical eddy diffusion transport and photochemistry in the terrestrial mesosphere and lower thermosphere (50-120 KM) (1981)
    In:  Other Sources
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    Publication Date: 2019-01-25
    Keywords: GEOPHYSICS
    Type: Illinois Univ. Middle Atmosphere Program. Handbook for MAP. Volume 2: (NASA-CR-175509); p 454-461
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  • 3
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    The vertical distribution of ozone in the mesosphere and lower thermosphere (1984)
    In:  Other Sources
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    Publication Date: 2019-06-28
    Description: An assessment is made of the ability of current theory to explain the phenomenology of upper atmospheric ozone as revealed by the sizeable body of measurements presently available. The chemical processes affecting the vertical distribution of ozone are reviewed, and simple analytical expressions for the ozone concentrations at different altitudes are derived which approximate the key elements of the ozone chemistry. These equations provide simple explanations of the sensitivity of model computations to the choice of rate constants and climatological patterns. Model calculations are compared with a detailed measurement of an ozone profile, and the model is modified to assess the variation in ozone expected to result from perturbations in key climatological processes. These predictions are then compared with the variability observed in midlatitude measurements in order to verify the model description of ozone processes in the upper atmosphere.
    Keywords: GEOPHYSICS
    Type: Journal of Geophysical Research (ISSN 0148-0227); 89; 4841-487
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  • 4
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    Seasonal variability of CO in the terrestrial mesosphere (1984)
    In:  Other Sources
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    Publication Date: 2019-06-28
    Description: Measurements were made of the J = 1 - 2 rotational transition of terrestrial mesospheric CO both in emission and in absorption against the moon on January 25-26, 1982. A CO mixing profile was obtained from the high signal-to-noise ratio emission spectrum. With the inclusion of these most recent spectra and spectra measured by Kunzi and Carlson (1982), further evidence is found suggesting seasonal variation of mesospheric CO as originally reported by Clancy et al. (1982). This seasonal variation may be the consequence of hemispheric circulation in the upper atmosphere.
    Keywords: GEOPHYSICS
    Type: Journal of Geophysical Research (ISSN 0148-0227); 89; 9673-967
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  • 5
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    Vertical transport and photochemistry in the terrestrial mesosphere and lower thermosphere /50-120 km/ (1981)
    In:  Other Sources
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    Publication Date: 2019-06-28
    Description: A study is conducted of the coupled effects of kinetics, solar cycle flux variations, and vertical transport on the distribution of long-lived hydrogen-carbon-oxygen compounds in the terrestrial mesosphere and lower thermosphere, using a one-dimensional aeronomy model. The calculations account for the important chemical reactions and use rocket measurements of the solar flux at solar minimum and maximum. Photodissociation rates appropriate for the mesosphere are determined with a spherical shell atmosphere formalism. Detailed corrections for the O2 Schumann-Runge bands and the temperature dependence of the CO2 cross sections are used. An eddy diffusion profile is derived which is in agreement with the Aladdin 74 mass spectral measurements of atomic O, O2, CO2, and Ar in the lower thermosphere and observations of the O3 minimum at about 80 km.
    Keywords: GEOPHYSICS
    Type: Journal of Geophysical Research; 86; May 1
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  • 6
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    Effective photodissociation cross sections for molecular oxygen and nitric oxide in the Schumann-Runge bands (1982)
    In:  Other Sources
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    Publication Date: 2019-06-28
    Description: Accurate calculations of the atmospheric opacity and the photodissociation rate of molecular oxygen in the Schumann-Runge bands (175-205) are necessary for modeling chemistry in the terrestrial upper atmosphere. The present investigation is concerned with a single simple parameterization of effective cross sections which can be used to calculate both O2 opacity and dissociation rates. Use is made of a zenith angle dependent factor which accounts for variations shown in detailed calculations. The conducted analysis is based on the results of Frederick and Hudson (1980). Attention is given to molecular oxygen effective cross sections and nitric oxide effective cross sections. It is found that the depth of the atmosphere to which solar radiation in the 175-200 nm spectral region penetrates is a sensitive function of the rotational line widths in the Schumann-Runge bands. The oscillator strength for each band measures the cross section integrated over the band while the line width determine how the absorption is distributed in wavenumber.
    Keywords: GEOPHYSICS
    Type: Journal of the Atmospheric Sciences; 39; Sept
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  • 7
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    Model ozone photochemistry on the basis of Solar Mesosphere Explorer mesospheric observations (1987)
    In:  Other Sources
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    Publication Date: 2019-07-12
    Description: Morning and afternoon mesospheric ozone profiles (50-90 km) measured by the Solar Mesosphere Explorer (SME) satellite are analyzed with one-dimensional photochemical models. The observed ozone abundances are 40 percent and 100 percent greater than the model ozone abundances at 50 and 80 km, respectively. Diurnal model calculations are compared with SME observations of ozone profiles at about 0400 and 1400 LT for high northern summer latitudes. Analysis of the ratios of these early morning and midafternoon ozone profiles provides the additional constraint that larger odd-oxygen production rates are required if lower odd-hydrogen activity is invoked to increase model O3 abundances. The increase in odd-oxygen production must be solar zenith angle independent in the mesosphere, ruling out significant changes in the Schumann-Runge band O2 opacities from Allen and Frederrick (1982).
    Keywords: GEOPHYSICS
    Type: Journal of Geophysical Research (ISSN 0148-0227); 92; 3067-308
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  • 8
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    A critical analysis of CLO and O3 in the mid-latitude stratosphere (1985)
    In:  Other Sources
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    Publication Date: 2019-07-12
    Description: The Caltech one-dimensional photochemical model is used to analyze important questions concerning the upper stratospheric O3 and the key HO(x), NO(x), and ClO(x) free radicals. The model is described and first order effects of the inclusion of diffuse radiation in a spherical rather than plane parallel atmosphere at solar zenith angles close to 90 deg are assessed. A comparison is made between photochemical theory and observations for upper stratospheric O3, where local photochemistry rather than dynamics should control the O3 abundance. The photochemical equilibrium relation for odd oxygen is studied, including the important radicals involves. It is concluded that a significant model ozone deficit exists in the upper stratosphere. Possible causes for such a discrepancy are investigated in light of current model and experimental uncertainties. In particular, the observational ratio of atomic oxygen to zone appears to disagree with the model results.
    Keywords: GEOPHYSICS
    Type: Journal of Geophysical Research (ISSN 0148-0227); 90; 12
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  • 9
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    A new source of ozone in the terrestrial upper atmosphere? (1986)
    In:  Other Sources
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    Publication Date: 2019-07-12
    Description: The simultaneous measurements of atomic O, O2, O3, and N2 between 90 and 110 km obtained by a rocket-borne mass spectrometer flown during the Aladdin 74 program provide an opportunity to test directly the simple atmosphperic chemical model first proposed more than 50 years ago by S. Chapman, which is today the core of the complex chemistry controlling stratospheric O3. The Aladdin 74 O3 results are found to be significantly in excess of model abundances computed using the most current values of the key chemical parameters. The calculations may possibly be in error due to uncertainties in these key parameters and/or in the measurement of the related species. However, the extra O3 may be a consequence of reactions between ground state O2 and electronically excited O2 resulting from the recombination of atomic O.
    Keywords: GEOPHYSICS
    Type: Journal of Geophysical Research (ISSN 0148-0227); 91; 2844-284
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