Determination of the O⁺(²P) ionization frequency using satellite airglow and neutral composition data and its implications on the EUV solar flux

Abstract

Simultaneous measurements of the O+(²D ‐ ²P) emission at 7319‐30Å and the atomic oxygen density in the optically thin region of the atmosphere offer a straightforward means of determining the photoionization frequency, I∞, for the production of O+(²P) ions. The ionization frequency is found to be 4.7 × 10−8sec−1 ±30% on June 8, 1974 and 3.4 × 10−8sec−1 ±30% on December 17, 1975. The wavelength dependent solar flux intensity in the relevant spectral region was also measured June 8, 1974 on the same spacecraft (Atmosphere Explorer‐C). A calculation of I∞ using this solar flux and currently accepted values of the photoionization excitation cross sections gives a value of 4.9 × 10−8sec−1, thus confirming the measured solar EUV flux.

Quenching of metastable ²Doxygen ions in the thermosphere by atomic oxygen

“…[1976] are given in Table 1. Tables 2 and 3 The data base that we use for this analysis has already been used in several other studies [e.g., Torr et al, 1976Torr et al, , 1977a. The neutral densities were measured by the open source mass spectrometer (OSS) [Nier et al, 1973], and the No.…”