Accession Number : AD0482178

Title :   THE DETERMINATION OF THE OPTICAL DEPTH AT LARGE SOLAR ZENITH DISTANCES,

Corporate Author : CENTRE NATIONAL DE RECHERCHES DE L'ESPACE BRUSSELS (BELGIUM)

Personal Author(s) : Swider, William, Jr.

Report Date : APR 1964

Pagination or Media Count : 45

Abstract : The determination of the optical depth of an atmosphere, i.e. the problem of determining the content of a column of molecules making an angle x with the zenith, is considered, particularly for large solar zenith distances. Chapman's solution for an atmosphere with constant mass, gravity and temperature is reviewed, and solutions are derived for constant scale height gradients of one-half and one. Approximations useful for numerical purposes are discussed. The earth's ionosphere is studied as an example of applications. The effect of gravity is taken into account. The general conclusion is that for x < or = 90 degrees the Chapman Function is applicable to the ionospheric situation within an error of + or -5% even though the temperature undergoes an important change in the 100-200 km region. It is emphasized that for x > pi/2 the optical depth must be specified in terms of the parameters at x = pi/2, i.e., at the maximum density point. It is shown that for ionospheric sunrise problems, the earth may be considered spherical and that one mean earth radius suffices for all optical depth calculations. (Author)

Descriptors :   (*IONOSPHERE, IONIZATION), ELECTROMAGNETIC RADIATION, SOLAR RADIATION, EARTH(PLANET), GRAVITY, DENSITY, GAS IONIZATION, ERRORS, SPHERES, UPPER ATMOSPHERE, ATMOSPHERIC TEMPERATURE, MOLECULAR PROPERTIES, EQUATIONS, FUNCTIONS(MATHEMATICS), MEASUREMENT, OPTICAL PROPERTIES, MATHEMATICAL ANALYSIS.

Subject Categories : Atmospheric Physics
      Numerical Mathematics

Distribution Statement : APPROVED FOR PUBLIC RELEASE