Relationships between ionospheric parameters derived from ionosonde observations and characteristics of post-sunset GHz scintillation during high solar activities (2012−2013) at Sanya (18.3°N, 109.6°E), China

Abstract

In this study, we presented the characteristics of post-sunset GHz scintillation occurrence and ionospheric parameters derived from ionosonde observations, including the critical frequency of F2-layer (foF2), peak height of F2-layer (hmF2), minimum virtual height of F-layer (h’F), scale height around the F2-layer peak (Hm), virtual height (h’F5) and true height (hF5) measured at 5 MHz, in high solar activity years (2012-2013) of solar cycle 24 at Sanya (18.3°N, 109.6°E; dip lat.: 12.8°N), China. Furthermore, we investigated the relationships between the equinoctial asymmetry of scintillation and these ionospheric parameters. In addition, the growth rates of Rayleigh-Taylor instability were calculated on the basis of the ionosonde measurements and models, respectively. The results showed that the equinoctial asymmetry of scintillation onset time would be associated with the scale length of vertical electron density gradient (L), which affects the growth of Rayleigh-Taylor instability at the bottom of F-layer. The seasonal variations of foF2, Hm and scale length of vertical electron density gradient would be the reason to cause the seasonal variations of scintillation occurrence, and the equinoctial asymmetry of scintillation occurrence rate over low latitude can be related to the background electron density and the vertical drifts around sunset in F-layer. The correlations between the scintillation strength represented by the daily maximum S4 and the daily maximum values of foF2, hmF2, h’F, Hm, and also the drifts over low latitudes were weak, which need to be further studied.