The nocturnal behavior of the hydroxyl airglow at the equatorial and low latitudes as observed by WINDII: Comparison with ground-based measurements

Measurements of the hydroxyl nightglow from the Wind Imaging Interferometer (WINDII) satellite-borne experiment and from ground-based photometers are compared and combined in order to characterize the hydroxyl airglow nocturn al behavior at 23 degrees S and the equatorial region. Ground-based observa tions at Cachoeira Paulista (23 degrees S, 45 degrees W) and at Fortaleza ( 4 degrees S, 38 degrees W) from 1987 to 1994 and WINDII data from March 199 2 to January 1994 are selected, and two periods are studied: the March/Apri l equinox and the December/January solstice; The WINDII results for the equ inox/solstice difference and for the nocturnal behavior of the vertically i ntegrated emission rate of the hydroxyl nightglow are found to be in very g ood agreement with the ground-based observations. The WINDII measurements r evealed two general characteristics of the hydroxyl nightglow altitude vari ation at the latitudes above. The hydroxyl nocturnal variations are predomi nantly occurring below 90 km, and the vertically integrated emission rate a nd the peak height of the volume emission rate show an inverse relationship with seasonal, latitudinal, and inter annual effects. The interpretation o f these results in terms of atmospheric tides is then discussed.