Thermospheric parameters contribution to the formation of Yakutsk F-layer diurnal summer time anomaly.

The role of thermospheric neutral composition in the formation of the Yakutsk diurnal summer time foF anomaly is analyzed. Ionospheric stations inside and outside the anomaly area are considered. The effect of neutral composition in foF is the most noticeable around noontime hours.

Daytime mid-latitude F-layer Q-disturbances: A formation mechanism.

Negative and positive near noontime prolonged (≥3 hours) F-layer Q-disturbances with deviations in NF > 35% occurred at Rome have been analyzed using aeronomic parameters inferred from f (plasma frequency at 180 km height) and fF observations. Both types of NF perturbations occur under quiet (daily Ap < 15 nT) geomagnetic conditions. Day-to-day atomic oxygen [O] variations at F-region heights specify the type (positive or negative) of Q-disturbance.

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

Longitudinal variations in the thermospheric neutral composition ([O] and [N]) and exospheric temperature Tex have been inferred from June monthly median noontime fF and fF 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/N ratios are comparable to TIMED/GUVI observations only under solar minimum conditions but differ substantially under high solar activity.