Twilight and nighttime ionospheric temperatures from oxygen 6300- and 5577-A spectral-line profiles.

Use of Fabry-Perot interferometer measurements of atomic-oxygen 6300- and 5577-A line profiles from twilight and nightglow to determine the neutral temperatures in the F2 and E regions of the earth's ionosphere. The exospheric temperatures determined from the 6300-A profiles are usually somewhat higher than the temperatures calculated from Jacchia's model, and differences as large as about 300 K are noted when the exospheric temperature equals 1500 to 1600 K. The postsunset and predawn rate of change of the exospheric temperature is often substantially larger than the Jacchia prediction. The 5577-A (E region) measured temperatures range from 200 to 220 K on quiet nights to 500 to 600 K during geomagnetic storms.