ROCKET OBSERVATION OF ATOMIC OXYGEN AND NIGHT AIRGLOW - MEASUREMENT OF CONCENTRATION WITH AN IMPROVED RESONANCE FLUORESCENCE TECHNIQUE

An improved resonant fluorescence instrument for measuring atomic oxyg en concentration was developed to avoid the Doppler effect and the aer odynamic shock effect due to the supersonic motion of a rocket. The sh ock effect is reduced by adopting a sharp wedge-shaped housing and by scanning of the detector field of view to change the distance between the scattering volume and the surface of the housing. The scanning ena bles us to determine absolute values of atomic oxygen concentration fr om relative variation of the scattered light signal due to the self-ab sorption. The instrument was calibrated in the laboratory, and the num erical simulation reproduced the calibration result. Using the instrum ent, the altitude profile of atomic oxygen concentration was observed by a rocket experiment at Uchinoura (31 degrees N) on 28 January 1992. The data obtained from the rocket experiment were not perfectly free from the shock effect, but errors due to the effect were reduced by th e data analysis procedure. The observed maximum concentration was 3.8 x 10(11) cm(-3) at altitudes around 94 km. The systematic error is est imated to be less than +/- 0.7 x 10(11) cm(-3) and the relative random error is less than +/- 0.07 x 10(11) cm(-3) at the same altitudes. Th e altitude profile of the OI 557.7-nm airglow was also observed in the same rocket experiment. The maximum volume emission rate was found to be 150 photons cm(-3) s(-1) at 94 km. The observed altitude profiles are compared with the MSIS model and other in situ observations.