Japan Geoscience Union Meeting 2016

Presentation information

International Session (Oral)

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

[P-EM09] Study of coupling processes in solar-terrestrial system

Mon. May 23, 2016 1:45 PM - 3:10 PM 106 (1F)

Convener:*Mamoru Yamamoto(Research Institute for Sustainable Humanosphere, Kyoto University), Satonori Nozawa(Institute for Space-Earth Environment Research), Yasunobu Ogawa(National Institute of Polar Research), Hiroyuki Hashiguchi(Research Institute for Sustainable Humanosphere, Kyoto University), Akimasa Yoshikawa(Department of Earth and Planetary Sciences, Kyushu University), Chair:Satonori Nozawa(Institute for Space-Earth Environment Research)

2:35 PM - 2:55 PM

[PEM09-10] Magnetic ripples as observed by low altitude satellites, CHAMP and SWARM

★Invited papers

*Toshihiko Iyemori1, Kunihito Nakanishi2, Tadashi Aoyama2, Yoko Odagi1 (1.Data Analysis Center for Geomagnetism and Space Magnetism, Graduate School of Science, Kyoto University, 2.Graduate School of Science, Kyoto University)

Keywords:magnetic ripples, small-scale field-aligned currents, acoustic gravity waves, low-altitude magnetic satellite

The low altitude satellites such as the CHAMP or the SWARM satellites have been observing the small amplitude (typically 0.5 – 5nT on the dayside) magnetic fluctuations with period of a couple of ten seconds. They exist almost all the time and at any local time (LT) in middle and low latitudes. They were named as “magnetic ripples” because the magnetic fluctuations like ripples exist globally.
They have the following characteristics: (1) They are perpendicular to the geomagnetic main field. (2) Their amplitude has the magnetic conjugacy. (3) The amplitude and the period along the orbit have latitudinal dependence, and they depend also on the geographic longitude. (4) The amplitude is larger on the day side than on the night side. (5) The amplitude doesn’t have dependence on the solar wind parameters nor the magnetic disturbance. (6) The amplitude has the following seasonal and topographical characteristics. That is, the amplitude during the northern summer and northern winter is larger than those during the equinoxes. In the northern summer, the amplitude over South America, Eurasia, North Africa and Australia continents, and their magnetic conjugate regions is larger than those in the other regions. In the northern winter, the amplitude over the eastern Pacific Ocean is larger.
We assume that they are generated through the E-region dynamo driven by the acoustic mode of the gravity waves propagated from lower atmosphere. We discuss the consistency of the above mentioned characteristics and suggested mechanism of generation of the magnetic ripples with ground based observations such as the GPS-TEC, micro-barometric observation, etc..