Calculation of the parameters of a spectrophotometric system for measuring airglow brightness in the upper atmosphere from space

Abstract

We present energy calculations for the basic parameters of a spectrophotometric system designed for recording the vertical distributions of the spectral brightness of hydroxyl airglow and the brightness of airglow from the green line of atomic oxygen in the upper layer of the Earth's atmosphere. We consider the scheme for conducting the "Hydroxyl" space experiment with instrumentation in the spectrophotometric system and methods for measuring the brightnesses of the indicated airglow components in sessions for observation of the Earth's night upper atmosphere in the altitude range 80-110 km from on board the International Space Station (ISS).Introduction. The optical glow of the atmosphere represents luminescence of atmospheric components at altitudes of 80-300 km and includes both individual emission lines and bands as well as a continuum. The hydroxyl (OH) emission bands make the largest contribution to the total energy of the airglow. Together with the continuum, they make up ≈87% of the total energy of the airglow. The contribution from the green line of atomic oxygen (OI) at 557.7 nm is ≈10%. ≈3 of the glow energy comes from the red line of oxygen at 630.0 nm, the sodium line, and lines for all the rest of the gases. The specifics of generation of the emissions from vibrational-rotational bands of OH and the 557.7 nm line of oxygen determines their high sensitivity to changes in the temperature and composition of the atmosphere. This airglow is used to determine the temperature and concentration of small gaseous components of the mesosphere, to study the dynamics of aeronomic processes and chemical kinetics at mesospheric temperatures, the nature of internal gravitational waves, for prediction of possible earthquakes from observed airglow variations. The latter application is the one of most practical importance.The characteristics of night airglow in the 557.7 nm and 630.0 nm oxygen lines, the sodium 589.0 nm, 589.6 nm lines, and the hydroxyl OH (8-3) bands were analyzed in connection with seismic activity in [1][2][3][4]. It was shown that during the "preparation" period and development of earthquakes, perturbations are observed in the indicated emissions on different time scales. In particular, for the OI 557.7 nm line, a substantial increase in the glow intensity was established within 1-2 days before an earthquake [3,4], with an abrupt decrease in the days following an earthquake.Despite the great practical importance and 50 years of research history, the mechanism of hydroxyl airglow still has not yet been quantitatively explained. Conducting experiments under space conditions with measurement of the vertical profiles of OH(v) and O( 3 P) airglow radiance followed by determination of the OH(v, J) populations and O( 3 P) concentrations will make it possible to refine the mechanisms of the processes and rate constants of reactions determining these airglow components and thus to make remote measurements of atmospheric parameters more reliable for practical purposes.In the A. N.