TropicalFregion winds from O I 1356-Å and [O I] 6300-Å emissions 1. Theory

Abstract

The time-dependent latitudinal distribution of the vertical column emission rates of O I 1356 A and [O I] 6300 A in the tropical region is theoretically investigated by numerically solving the coupled nonlinear system of time-dependent continuity equations for the ions O+, O2+, NO+, N2+, and N+ in which production and loss of ionization, ambipolar diffusion, E × B drifts, and neutral winds are taken into account. Radiative recombination, ion-ion neutralization, and dissociative recombination are considered as main mechanisms in producing the atomic oxygen tropical nightglow. The specific effects of neutral winds and plasma drifts on the emissions and the time response of the ionosphere and airglow to changes in the wind velocity are investigated. A quantitative relationship is obtained between the neutral wind velocities and the resultant asymmetry about the magnetic equator in the airglow emissions. The method is useful for studying the neutral wind system in the tropical ionosphere.