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.
Highlights
A nighttime ionospheric phenomenon in the equatorial and low-latitude region, known as spread F (SF), has been extensively investigated for many years since it was first observed by Booker and Wells (1938)
Our results showed that the maximum occurrence rates of range spread F (RSF), frequency spread F (FSF) and mix spread F (MSF) were in summer months at Puer station
We suggested that the nighttime medium-scale traveling ionospheric disturbance (MSTID) might play a significant role in forming RSF, FSF and MSF at Puer station in the present study
Summary
The occurrence rate of SF observed at Puer during 2015–2016 shows obvious dependence on local time and season. The dependences of different types of SF on solar activity and geomagnetic activity are varied with season.
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