USING STARS FOR REMOTE-SENSING OF THE EARTHS STRATOSPHERE

A new UV-visible spectrometer system that measures the absorption of l ight from stars and planets by constituents in the Earth's atmosphere is described. Because it can be used to make measurements at night, th e system has a significant advantage for measuring polar constituents in winter, when conditions that might give rise to ozone loss are init iated. Other advantages arise from the use of a cooled two-dimensional CCD array as the detector: an array detector avoids spectral noise re sulting from scintillation of stars or from clouds passing overhead an d allows for the possibility of measuring several constituents simulta neously; its second dimension permits auroral light from the atmospher e adjacent to the star to be measured simultaneously and subtracted fr om the stellar light, and a modern low-noise CCD allows us to use a te lescope of modest diameter. The few previous measurements of constitue nts made by the used of stellar absorption did not have these advantag es. The instrument was configured for simplicity and ease of use in fi eld measurements and was deployed outside in winter in Northern Sweden in 1991. Examples of ozone measurements are shown.