Japan Geoscience Union Meeting 2021

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[E] Oral

P (Space and Planetary Sciences ) » P-EM Solar-Terrestrial Sciences, Space Electromagnetism & Space Environment

[P-EM09] Dynamics of Magnetosphere and Ionosphere

Sun. Jun 6, 2021 3:30 PM - 5:00 PM Ch.05 (Zoom Room 05)

convener:Akiko Fujimoto(Kyushu Institute of Technology), Mitsunori Ozaki(Faculty of Electrical and Computer Engineering, Institute of Science and Engineering, Kanazawa University), Yuka Sato(Nippon Institute of Technology), Aoi Nakamizo(Applied Electromagnetic Research Institute, National Institute of Information and Communications Technology), Chairperson:Yuki Obana(Department of Engineering Science, Faculty of Engineering, Osaka Electro-Communication University), Yoshihiro Yokoyama(Department of Earth and Planetary Sciences, Graduate School of Science, Kyoto University)

3:30 PM - 3:45 PM

[PEM09-20] Seasonal dependence of dusk-side equatorial IHFACs polarity during solar cycle 23-24

Manjula Ranasinghe2, *Akiko Fujimoto1, Akimasa Yoshikawa3, Chandana Jayaratne2 (1.Kyushu Institute of Technology, 2.University of Colombo, 3.Kyushu University)

The east-west ward variation of MAGDAS/CPMN magnetometer 1-hour time resolution data at Davao (Philippines) station operated by International Center for Space Weather Science and Education, Kyushu University from August 1998 to July 2020 are used to investigate the characteristics of the long-term Inter-hemispheric field-aligned currents (IHFACs). The recent in-situ satellite and ground-based observations have reported the dusk-side current polarity of IHFACs are often inconsistent with the Fukushima’s IHFACs model. We investigated whether the dusk-side IHFACs polarity is consistent or not with the current direction predicted by Fukushima’s IHFACs model, by analyzing the time-series data of IHFACs variations. We confirmed that the solstices dusk IHFACs flow the same direction of noon IHFACs and the equinoxes dusk IHFACs disagree with Fukushima’s model. Seasonal IHFACs variations exhibited remarkable asymmetry in both dawn and noon sectors. By contrast, the profile of dusk-side IHFACs intensity was symmetry. The difference between noon and dusk IHFACs intensity might be strongly related to the seasonal dependence of the dusk IHFACs polarity. In addition, we presented that solar cycle dependence can be seen in the peak-to-peak amplitude, monthly average and yearly integral intensity of IHFACs. In contrast to annual variations of IHFACs polarity in the dawn/noon sectors, there were multiple periodicities in the dusk sector: annual variation during the declining phase of solar cycle and semiannual or terannual variations during the increasing and maximum phase. The dusk-side IHFACs modulations were more related with F10.7 variability compared with the dawn and noon sectors. It suggests that the dusk IHFACs is affected by the solar cycle activities.