Japan Geoscience Union Meeting 2019

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[E] Oral

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

[P-EM12] Space Weather and Space Climate

Mon. May 27, 2019 3:30 PM - 5:00 PM A04 (TOKYO BAY MAKUHARI HALL)

convener:Ryuho Kataoka(National Institute of Polar Research), Antti A Pulkkinen(NASA Goddard Space Flight Center), Kanya Kusano(Institute for Space-Earth Environmental Research, Nagoya University), Kaori Sakaguchi(National Institute of Information and Communications Technology), Chairperson:Kanya Kusano(Nagoya University)

4:45 PM - 5:00 PM

[PEM12-24] Spring-Autumnal asymmetry in geomagnetic activity and its origin over last 140 years

*Hao Luo1, Xiaoming Sha1 (1.IGGCAS)

Keywords:Spring-Autumnal asymmetry, Solar magnetic polarity

Spring-Autumnal asymmetry (SA asymmetry) from years 1873-2010 in the geomagnetic activity is investigated based on the geomagnetic indices (aa, Ap and Kp). Results have shown that in general the SA asymmetry of the geomagnetic activity appears to be alternation, except for the interval during which the change of dominant solar dipole magnetic field polarity occurs. Our study implies that both the polarity of the main solar dipole field and the north-south asymmetry of the sunspot area in the two solar hemispheres control the strength of the south component (Bs) of the interplanetary magnetic field (IMF) near the Earth and the resulting SA asymmetry of the geomagnetic activity in the corresponding seasons. A simple sector structure model is devised to establish the relationship between the polarity of solar main dipole magnetic field, the IMF Bs component and the corresponding SA asymmetry in the geomagnetic activity. This is confirmed by examining the solar wind parameters from the spacecraft observations during the recent decades.