Longitudinal differences in the statistical characteristics of ionospheric spread-F occurrences at midlatitude in Eastern Asia

• Published in: Earth, planets, and space planets, and space, 2019-04, Vol.71 (1), p.1-15, Article 47
• Main Authors: Wang, Ning, Guo, Lixin, Ding, Zonghua, Zhao, Zhenwei, Xu, Zhengwen, Xu, Tong, Hu, Yanli
• Format: Article
• Language: English
• Subjects: 3. Space science; Acoustic gravity wave; Earth and Environmental Science; Earth Sciences; Eastern Asia; Electron density; F region; Geological research; Geology; Geomagnetic fields; Geomagnetism; Geophysics/Geodesy; Ionosondes; Ionosphere; Latitude; Longitudinal difference; Observations; Occurrence percentages; Offshore structures; Perkins instability; Spread-F; Upper atmosphere
• ISSN: 1880-5981; 1343-8832; 1880-5981
• DOI: 10.1186/s40623-019-1026-6

Spread-F is known as the electron density inhomogeneous structures in F layer of ionosphere and can usually be classified as frequency spread-F (FSF) and range spread-F (RSF). Few studies have reported on the statistical characteristics of spread-F occurrences at midlatitudes in Eastern Asia, particularly the comparison of spread-F occurrences between China and Japan. In this paper, we used spread-F data recorded by ten ionosondes located between 25°N and 45°N from 1997 to 2016, to investigate the longitudinal differences in the statistical characteristics of spread-F occurrence and the probable mechanism for its occurrence at midlatitudes in Eastern Asia. Variations in the spread-F occurrences with the solar and geomagnetic activities, season and local time are presented. The main conclusions are as follows: (a) the occurrence percentage of FSF is higher than that of RSF, of which the former is anti-correlated with the solar or geomagnetic activities; (b) higher FSF occurrence percentages mostly appeared during summer, while RSF occurred more frequently in winter near 45°N latitude such as Urumqi, Changchun and Wakkanai; (c) the maximum of the FSF occurrence percentages mostly appeared between 01:00 and 02:00 LT approximately, whereas that of RSF appeared near 00:00 LT; (d) the spread-F occurrence percentages in the coastal or marine areas are higher than those in the inland region between 35°N and 45°N latitudes; however, this phenomenon is not obvious at lower latitudes; and (e) both the mean occurrences of FSF and RSF reach the minimum around 31°N latitude. These above results are helpful for understanding variations in spread-F occurrence at midlatitudes in Eastern Asia.