Molecular oxygen concentrations in the upper atmosphere by absorption spectroscopy

Abstract

Measurements of molecular oxygen from 68 to 154 km using rocket‐borne ultraviolet photometers are described. During summer, diurnal variations are found in the altitude range 93–104 km between dawn and daytime, the dawn concentrations being less by a fractional change in the average concentration of about 33%. Concentrations above 114 km in the spring agree with other measurements, but show rather large deviations from the CIRA 1965 mean atmosphere. Seasonal differences, observed below 90 km, generally support the variations observed in the total neutral atmosphere by other techniques.

Seasonal variations in molecular oxygen near 100 km

“…The Lyman a data, however, do show that the altitude of equal density values is 2 km lower at sunrise than at sunset, suggesting a diurnal variation with maximum values at sunset. A similar diurnal variation was noted much earlier by rocket experiments made in the 1964-1966 period by Weeks and Smith [1968].…”

The measurement of O2number density by absorption of Lyman α

“…where F is the optical depth if actor, which may be approximated by sec X as long as the solar zenith angle (X) is not large. For large angles, as at sunrise, F is calculated from the scale height, which is first obtained by plotting l-•(dI/dz) against z [ Weeks and Smith, 1968]. The use of this technique in the atmosphere is limited to certain gases for which a wavelength can be specified at which the gas being measured is the only, or major, absorber.…”

Venus: An Upper Limit on Intrinsic Magnetic Dipole Moment Based on Absence of a Radiation Belt

“…Extinction measurements of N 2 and O have been obtained [Hall et al, 1967;Hinteregger and Hall, 1969;Thomas and Bruner, 1969]. Molecular oxygen concentrations have been determined by this technique by Weeks and Smith [1968], Norton and Warnock [ 1968], Opal and Moos [ 1969 ], and Reid and Withbroe [1970]. The recent mass spectrometer and EUV extinction measurements of N 2 , 0 2 , and Ar generally indicate lower values than are given in atmo spheric models such as USSAS.…”