A Novel Study on the Technique for Deriving O/N2 from Thermospheric Far Ultraviolet Dayglow Emissions

Abstract

The far ultraviolet dayglow emissions of the thermosphere, produced by the photoelectrons impact on the atomic oxygen or the nitrogen molecules, are the most important emissions used as remote sensing signals in the far ultraviolet emission range. The column density of the atomic oxygen relative to the nitrogen molecules, denoted by the quantity O/N2 which is used as the monitor for the space weather of the upper atmosphere, can be derived from simultaneous measurements of the disk-viewing OI 135.6 nm and the LBH dayglow emission. In this paper, the solar activity and geomagnetic activity are both considered and researched for the technique of making use of these two far ultraviolet dayglow emissions to obtain O/N2. An important finding is that the intensity ratio 135.6/LBH is seen to vary linearly with the intensity of the solar activity and the geomagnetic activity. Then, the reason why the solar activity and the geomagnetic activity have different effects on the O/N2 retrieval curves was briefly analyzed and discussed. Finally, the effects of the solar activity and the geomagnetic activity to the O/N2 retrieval technique are verified. And the result shows that the solar activity can result in dispersal for the O/N2 retrieval curve, and the geomagnetic activity has no effect on the O/N2 retrieval curve. This work provides a solid basis for the development of the O/N2 retrieval technique, and this technique will play an important role in monitoring the space weather of the thermosphere.