Observing earth's sodium and atomic oxygen dayglow emissions

The observation of sodium emission in the twilight upper atmosphere was the leading edge of the study of metals in the upper atmosphere, and its quantitative measurement and analysis were pioneered by Donald M. Hunten. He extended these early observations into the daytime, the sodium dayglow, including rocket observations of this phenomenon. More than fifty years later the amount of information on this subject has grown enormously through LIDAR observations, laboratory measurements, and extensive modeling. The author's participation in those early measurements inspired him to undertake observations of the atomic oxygen dayglow, first from the ground, and then from orbit with the WINDII instrument on NASA's Upper Atmosphere Research Satellite. The parallels between the Na and O dayglows are described and reviewed, including in particular the methods of observation. Very recent results on the atomic oxygen O(¹S) dayglow are presented, showing the influence of the DE3 nonmigrating tide reaching from the troposphere to 250 km altitude in the thermosphere. (author)