Longitudinal variations in thermospheric parameters under summer noontime conditions inferred from ionospheric observations: A comparison with empirical models

Andrey V Mikhailov; Loredana Perrone

doi:10.1038/s41598-019-49255-1

Longitudinal variations in thermospheric parameters under summer noontime conditions inferred from ionospheric observations: A comparison with empirical models

Sci Rep. 2019 Sep 4;9(1):12763. doi: 10.1038/s41598-019-49255-1.

Authors

Andrey V Mikhailov^{1

2}, Loredana Perrone³

Affiliations

¹ Pushkov Institute of Terrestrial Magnetism, Ionosphere and Radio Wave Propagation (IZMIRAN), Moscow, Russia.
² Istituto Nazionale di Geofisica e Vulcanologia (INGV), Rome, Italy.
³ Istituto Nazionale di Geofisica e Vulcanologia (INGV), Rome, Italy. loredana.perrone@ingv.it.

Abstract

Longitudinal variations in the thermospheric neutral composition ([O] and [N₂]) and exospheric temperature Tex have been inferred from June monthly median noontime f_oF₁ and f_oF₂ observations at mid-latitudes to check for consistency with empirical MSIS models. In general, a similarity in longitudinal variations has been demonstrated, and this is interesting, as similar variations were obtained with very different methods and different data sources. Both inferred and MSISE-00 modelled height-integrated O/N₂ ratios are comparable to TIMED/GUVI observations only under solar minimum conditions but differ substantially under high solar activity. The retrieved height-integrated O/N₂ ratio longitudinal variations are small (∼15%) in comparison to the observed N_mF₂ variations under high solar activity. The height-integrated O/N₂ ratio cannot be incorporated into the F₂-layer formation mechanism; therefore, such observations cannot be used for any quantitative interpretation of N_mF₂ variations.