Implications of odd oxygen observations by the TIMED/SABER instrument for lower D region ionospheric modeling
2015 (English)In: Journal of Atmospheric and Solar-Terrestrial Physics, ISSN 1364-6826, Vol. 124, 63-70 p.Article in journal (Refereed) Published
We document the variability in atomic oxygen inferred by the Sounding of the Atmosphere with Broadband Emission Radiometry (SABER) instrument on the NASA/TIMED satellite in the lower mesosphere (50-80 km altitude) according to its diurnal, latitudinal, seasonal and solar cycle components. The dominant variation is diurnal and latitudinal. Below 75 km, seasonal and solar cycle effects are less than 5%. Accordingly, we have developed a simple climatology that depends upon local time and latitude and applied it to a model of the D region of the ionosphere. Between 60 and 70 km, atomic oxygen is important in governing the ratio of negative ions to electrons. Using the SABER O climatology along with a previously published climatology of nitric oxide based upon UARS/HALOE data, we compare our model results both to previous calculations and to a profile of electron density [e(-)] acquired by a rocket launched from Kwajalein Atoll. The model results are shown to be consistent with previously published calculations, but the comparison with the data reveals a dramatic discrepancy whereby the calculated [e(-)] is over an order of magnitude less than the observations below 65 km. The most plausible explanation involves changing the partition of negative charge between molecules such as O-2 which rapidly dissociate in sunlight versus heavier, more stable negative ions. Although observations of [e(-)] below 70 km are difficult and infrequent, more research should be invested to evaluate the pervasiveness and the seasonal, latitudinal and diurnal morphology of this model [e(-)] deficit. This may have practical implications as empirical models of the ionosphere predict a secondary maximum in HF radio absorption in the 70 km altitude region.
Place, publisher, year, edition, pages
2015. Vol. 124, 63-70 p.
Mesosphere, Ionosphere, D region
Earth and Related Environmental Sciences
IdentifiersURN: urn:nbn:se:su:diva-115992DOI: 10.1016/j.jastp.2015.01.014ISI: 000350529800008OAI: oai:DiVA.org:su-115992DiVA: diva2:802070