Measurement of atomic oxygen in the lower ionosphere using a rocket-borne resonance lamp

ATOMIC oxygen is an important constituent of the mesosphere and lower thermosphere because of its role in the excitation of the O I( 1 S 0 - 1 D 2 ) airglow emission at 557.7 nm (ref. 1) and because of its involvement in the positive and negative ion chemistry of the lower ionosphere 2 . In particular it destroys negative ions 3 and can break reaction chains believed to produce water cluster ions below about 85 km (ref. 4). There is also uncertainty about the degree of dissociation of oxygen in the thermosphere 5,6 and atomic oxygen is involved in many reactions with neutral hydrogen/oxygen compounds in the mesosphere 7 .