The Occurrence Characteristics of Daytime Irregularities in the Low Latitude Topside F Region at Solar Minimum Revealed by ICON

Abstract

AbstractUsing observations from the Ionospheric Connection Explorer satellite, the occurrence characteristics of daytime plasma density irregularities in the low latitude topside F region at solar minimum were studied. The results show that the occurrence characteristics of daytime topside irregularities during June solstice resembled those at solar maximum. An interesting phenomenon not reported before is that an occurrence minimum in the local‐time variation occurred around 08:30–10:00 LT, mainly during Equinox in Asia. The topside irregularities appearing after the occurrence minimum were mostly concentrated at low latitudes around ±5°–15°. Based on the total electron content perturbations derived from the ground‐based global navigation satellite system receivers at low latitudes, it was found that the topside irregularities after the occurrence minimum were accompanied with apparent medium‐scale traveling ionospheric disturbances (MSTIDs) at times. Statistically, a good agreement was observed between the local time variations of MSTIDs and of daytime topside irregularities during Equinox in East/Southeast Asia. We suggest that the daytime irregularities in the low latitude topside F region were not totally the remnants of nighttime equatorial plasma bubbles. Especially for the daytime irregularities during Equinox in Asia, they could be MSTIDs appearing at topside F region.