Stratospheric studies using tunable laser spectroscopy

Abstract

This paper reviews recent experiments of spectroscopic determination of stratospheric NO and H20 using opto-acoustic techniques with a spin-flip Raman (SFR) laser as the source of tunable infrared (IR) radiation. The interest in the measurement of stratospheric NO arises from the important catalytic destruction role it is presumed to play in the stratospheric ozone balance. Recent model calculations 1 have indicated the detrimental effects of additionally introduced NO into the stratosphere in reducing the 03 concentration and the subsequent increase in the short wavelength ultraviolet (UV) radiation reaching the earth 2. The increased UV radiance has undesirable biological implications which have received considerable attention recently. In addition, a reduction in 03 concentration is predicted according to a model which considers the diffusion of chlorofluoromethanes into the stratosphere, their subsequent breakdown in the stratosphere by the short wavelength UV radiation which does not reach ground level, and finally the release of chlorine which, through recombination with ozone and atomic oxygen to form CIO enters into the catalytic destruction of ozone 3 in a manner that is similar to that of NO. While this paper focusses its attention primarily on the NO measurements (with a minor importance placed on H20 measurements) , it will be seen that the spectroscopic nature of the technique described here is general enough to allow quantitative determination of a considerably larger number of stratospheric constituents of interest.