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One of the more chalenging problems in spectroscopy is the detailed determination of the composition of the upper atmosphere. A traditionally fruitful technique has been solar spectroscopy in the visible and infrared regions of the spectrum (Ref. 1), where the attenuation spectrum of direct sun light is analysed. More indirect solar spectroscopy has been used to monitor ozone concentrations via the Umkehr effect. Some years ago a survey was made of the airglow emission spectrum in the infrared using balloon borne fourier transform spectrometers (Rars. 2,3,4). This means of observation is highly complementary to solar spectroscopy in that it provides good sensitivity for detection of small concentrations of excited molecules such as OH. In optimizing the absorption path through the atmosphere by means of balloon borne solar spectroscopy and very low sun positions, it has been possible to observe very small traces of HNO3 (Rai% 5). Since attention was drawn to the possible role of NO as a catalytic agent in the destruction of ozone by Crutzen (Ref. 6), this gas as well as NO2 has been observed in long path solar spectra (Refs. 7, 8) and NO by chemiluminescent analysis of air samples (Ref. 9). In attempting to understand the different processes of chemistry, photochemistry and circulation taking place in the upper atmosphere it is necessary to make more than a few measurements to identify suggested molecules. We have initiated a program of measurements that is intended to provide a general survey of minor constituents in the upper atmosphere that may be ob-servable by means of improved ground based spectroscopic techniques. With the ground based technique it becomes possible to consider relatively economical means of monitoring these constituents both temporally and geographically.
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