Statistical analysis of low-latitude spread F observed over Puer, China, during 2015–2016

Abstract

Statistical analysis of spread F (SF), recorded at Puer (PUR, 22.7° N, 101.05° E, Dip Latitude 12.9° N) during 2015-2016, was carried out to reveal its characteristics at the northern equatorial ionization anomaly. In our study, SF was categorized into four types, frequency spread F (FSF), range spread F (RSF), mix spread F (MSF) and strong range spread F (SSF). The statistical results presented that FSF and MSF were dominant over Puer. Most types of SF appeared mostly in summer months, except the maximum occurrence of SSF in equinox months. Moreover, observations of SF events also showed that the solar activity and magnetic activity dependence of SF varied with seasons. Compared with observations at other region, the present results suggest that medium-scale traveling ionospheric disturbances (MSTIDs) may play a key role in generation of SF in low-latitude region.

Ionospheric F Layer Scintillation Weakening as Observed by COSMIC/FORMOSAT‐3 During the Major Sudden Stratospheric Warming in January 2013

“…Strong seasonal/longitudinal variability of the EFIs occurrence rate has been recognized as a result of varying longitudinal gradient in the integrated E region conductivity, with a tendency of higher EFIs occurrence when the sunset terminator is aligned with the geomagnetic field lines (Carter et al, 2013;Dymond, 2012;Tsunoda, 1985). Other researchers found the positive correlation between the EFIs generation and solar activity, with EFIs detected more during solar maximum period and less during solar minimum years (Basu et al, 1988;Bhaneja et al, 2018;Carter et al, 2013;Lan et al, 2019;Pezzopane et al, 2013;Pietrella et al, 2017;Yu et al, 2018). It is well known that EFIs can affect the transionospheric radio wave, leading to so-called ionospheric scintillation, that is, rapid fluctuation in the amplitude and/or phase of the received signals (Alfonsi et al, 2013;Yeh & Liu, 1982).…”

Spread-F characteristics at the southern anomaly crest in South America during the descending phase of solar cycle 24

“…Our results are partially consistent with those of Whalen (2002), who used an array of ionospheric sounders in the western American sector during solar maximum and showed that spread-F decrease with increasing Kp during equinox and summer, but they found no correlation in winter. Lan et al (2019) analysed ionograms recorded at the northern equatorial ionization anomaly in China. They reported a positive correlation for all types of spread-F in winter, an inverse correlation for SSF during equinox and summer, and for FSF in summer.…”

Spread-F characteristics over Tucumán near the southern anomaly crest in South America during the descending phase of solar cycle 24

“…They showed that at Huancayo, Peru, spread-F was more frequent on disturbed than on quiet days during the June solstice (local winter). Lan et al (2019) analysed ionograms recorded at the northern equatorial ionization anomaly in China. They reported a positive correlation for all types of spread-F in winter, and for RSF in all seasons, whereas the found an inverse correlation for FSF in summer.…”

“…They concluded that exist a connection between RSF occurrence and medium-scale TIDs due to gravity wave propagation. Lan et al (2019) suggested that night-time MSTIDs might play a signi cant role in the occurrence of RSF and FSF over Puer, China, at the northern EIA. Moreover, Pimenta et al (2008) showed that, in the Brazilian region, night-time spread-F can be caused by night-time mid-latitudes MSTIDs that propagate toward low latitudes.…”