DOPPLER DETECTION OF HYDROXYL COLUMN ABUNDANCE IN THE MIDDLE ATMOSPHERE

The hydroxyl column abundance in the middle atmosphere is measured wit h ground-based uv spectroscopy using the sun as a light source. The pr esent method is distinctive in that it utilizes the Doppler shift of t he solar spectrum due to the solar rotation to discriminate the slight terrestrial hydroxyl absorption from prominent solar features. By com paring the spectra measured on the east and the west edges of the sola r disk, it is possible to cancel out most of the solar structures and to make the terrestrial features much more evident.