@article{oai:kyutech.repo.nii.ac.jp:00006237,
 author = {Fujimoto, Akiko and 藤本, 晶子 and Uozumi,  Teiji and Abe,  Shuji and Matsushita,  Hiroki and Imajo,  Shun and Ishitsuka,  Jose K. and Yoshikawa,  Akimasa},
 issue = {1},
 journal = {Sun and Geosphere},
 month = {},
 note = {In 2008, International Center for Space Weather Science and Education, Kyushu University (ICSWSE) proposed the EE-index, which is an index to monitor the equatorial geomagnetic phenomena. EE-index has been improved with the development of the MAGnetic Data Acquisition System and the Circum-pan Pacific Magnetometer Network (MAGDAS/CPMN) and the enormous archive of MAGDAS/CPMN data over 10 years since the initial article. Using the improved EE-index, we examined the solar cycle variation of equatorial electrojet (EEJ) by the time series analysis for EUEL (one part of EE-index) at Ancon in Peru and the solar activity from September 18, 1998 to March 31, 2015. We found that the long-term variation of daily EEJ peak intensity has a trend similar to that of F10.7 (the solar activity). The power spectrum of the daily EEJ peak has clearly two dominant peaks throughout the analysis interval: 14.5 days and 180 days (semi-annual). The solar cycle variation of daily EEJ peak correlates well with that of F10.7 (the correlation coefficient 0.99). We conclude that the daily EEJ peak intensity is roughly determined as the summation of the long-period trend of the solar activity resulting from the solar cycle and day-to-day variations caused by various sources such as lunar tides, geometric effects, magnetospheric phenomena and atmospheric phenomena. This work presents the primary evidence for solar cycle variations of EEJ on the long-term study of the EE-index., 2015 UN/Japan Workshop on Space Weather, 2-6 March 2015, Fukuoka, Japan},
 pages = {37--47},
 title = {Long-term EEJ variations by using the improved EE-index},
 volume = {11},
 year = {2016},
 yomi = {フジモト, アキコ}
}