Preliminary Results from the Meteorological Office on Ariel 3

Abstract

THE British–American satellite Ariel 3 carried a Meteorological Office experiment¹ to observe the distribution of molecular oxygen in the lower thermosphere by making measurements of the attenuation of solar ultraviolet radiation at about 1450 Å. Two observations were made in each orbit, at satellite sunrise and sunset, but data will be available for only about one third of these observations—those made within range of a telemetry station (the satellite's tape recorder could not be used for this experiment). Most of the observations made in the first ten days of satellite life (May 5–14, 1967) have now been reduced, by fitting to them a model of the O₂ distribution having the form in which N is the number density of oxygen molecules at a height of 180 km, 2 H₁H₂/(H₁ + H₂) is the local scale height (in km) for O₂ at 180 km and H₁ and H₂ are limiting values of scale height at small and large heights. The attenuating cross-section for an oxygen molecule was assumed to be 1.48 × 10⁻¹⁷ cm² (ref. 2).