The direct measurement of nitric oxide concentration in the upper atmosphere by a rocket‐borne chemiluminescent detector

Abstract

Direct measurements of the nitric oxide concentration between 42 km and 60 km have been made with a rocket‐borne chemiluminescent detector. The first flight of this instrument was primarily a demonstration of feasibility; some instrument parameters were not measured but, instead, calculated assuming a standard atmosphere (USSA 1962) and a known vehicle velocity profile. The rocket was fired from Wallops Island, Virginia on 8 April, 1975 at 1405 LT. Our results are: Altitude (km) Mixing Ratio NO Density (number/cc) 42 (4.2 ± 2.3)× 10 −9 (2.6 ± 1.4)× 10 8 45 (3.6 ± 2.0)× 10 −9 (1.5 ± 0.9)× 10 8 50 (2.2 ± 1.4)× 10 −9 (4.6 ± 2.9)× 10 7 55 (2.5 ± 1.6)× 10 −9 (3.1 ± 1.9)× 10 7 60 (5.2 ± 2.9)× 10 −9 (3.4 ± 1.9)× 10 7 Corrections to the data have been made to account for an ozone‐generated background emission that set a lower limit of detectability of about lppb. Since the background emission was not measured during the flight but, instead, simulated in the laboratory, we regard these results as being upper limits on the NO concentration that prevailed at that particular time and location.