Radiometric measurements of emission from stratospheric water vapour

Abstract

Measurements of the total downward emission from the earth's atmosphere in the region 5.5 to 8 μ have been made to heights around 30 km using a balloon‐borne radiometer. The instrument employs a liquid‐air cooled detector of gold‐doped germanium, the responsivity of which increases with height, enabling measurements to be made over about four orders of magnitude. An all‐up weight of 2.5 kg allows the apparatus to be carried on a conventional radiosonde balloon. A method has been devised for interpreting ascent data in terms of the distribution of atmospheric water vapour. The analysis of an ascent made in September 1963 is described in detail. Results are presented which indicate stratospheric mixing‐ratios in the region of 3 × 10−6 g g−1 at least up to 25 km. A large downward flux of radiation observed at the highest altitude was interpreted as emission from sources other than water vapour. Copyright © 1965 Royal Meteorological Society