Ultraviolet laser sounding of the troposphere and lower stratosphere

Abstract

WE report here measurements made with a ground-based, ultraviolet laser operating in the wavelength range 297–308 nm, which relate to the question of the atmospheric transmission between ground level and about 20 km, and particularly to the contributions of absorption by minor constituents. There has been considerable concern in recent years about the biological effects of increased solar ultraviolet radiation at ground level associated with a reduction in the concentration of atmospheric ozone1. It seems that wavelengths between about 300 and 310 nm are most likely to produce erythema (sun burn) and skin cancer2. The effects of aerosols, clouds, non-absorbing haze or fog and other absorbing atmospheric gases need to be considered in addition to the effects of ozone and of Rayleigh scattering when examining the penetration of these radiations to the Earth's surface3,4. Except for the Junge layer5 of aerosols which extends from about 12 to 22 km, and cirrus clouds, these scattering and absorbing agencies are probably located in the lower troposphere, below about 5 km.