Diurnal variation of the atmosphere around 190 kilometers derived from solar extreme ultraviolet absorption measurements

The atmospheric attenuation of solar extreme ultraviolet radiation in early morning, June 1962, and late afternoon, October 1962, has been measured. The derived atmospheric composition change in the 170- to 210-km region is interpreted mainly as a diurnal effect. The molecular nitrogen concentration is seen to change but little, while the molecular oxygen concentration decreases by about twenty per cent and the atomic oxygen concentration increases by a factor of about 2 in the afternoon.