Balloon borne in‐situ detection of OH in the stratosphere from 37 to 23 km

The OH number density in the stratosphere has been measured over the altitude interval of 37 to 23 km at midday via a balloon‐borne gondola launched from Palestine, Texas on July 6, 1988. OH radicals are detected with a laser induced fluorescence instrument employing a 17 kHz repetition rate copper vapor laser pumped dye laser optically coupled to an enclosed flow, in‐situ sampling chamber. OH abundances ranged from 88±31 pptv (1.1 ± 0.4 × 107 molec cm−3) in the 36 to 35 km interval to 0.9 ± 0.8 pptv (8.7 ± 7.7 × 105 molec cm−3) in the 24 to 23 km interval. The stated uncertainty (±1σ) includes that from both measurement precision and accuracy. Simultaneous detection of ozone and water vapor densities was carried out with separate on‐board instruments.