Day and night measurements of ozone in the Southern Hemisphere

Measurements of ozone using Dobson spectrophotometers at night on the moon in low and middle latitudes of the Southern Hemisphere and calculated by the ‘ AD ’ method did not show any significant difference between day and night. However, the ozone amounts calculated using individual wavelength pairs, without applying the haze correction, usually showed an increase in ozone at night, implying that the apparent increase in ozone was due to an increase in large particle scattering at night. In middle latitudes, at Aspendale, Hay and Hobart, observations at night on the B (λλ 3088/3291) pair of wavelengths showed an apparent decrease of ozone at night. At Darwin, in low latitudes, there was no difference between day and night ozone when calculated on the B pair of wavelengths. This implies that greater radiation is received at the Earth's surface on about λ 3088, in middle latitudes. This enhanced radiation is tentatively attributed to the emission from the Herzberg band of molecular oxygen and to (terrestrial) OH emission at λ 3088, at night in middle latitudes. The latitudinal observations and their interpretations are consistent with existing knowledge regarding these emissions. The absorption coefficients of ozone as calculated from Southern Hemisphere atmospheric measurements at these wavelengths and at these places differ from those obtained by Vigroux, but are consistent with those obtained by Dobson and Ramanathan in the Northern Hemisphere.