Japan Geoscience Union Meeting 2016

Presentation information


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

[P-EM16] Physics and Chemistry in the Atmosphere and Ionosphere

Tue. May 24, 2016 5:15 PM - 6:30 PM Poster Hall (International Exhibition Hall HALL6)

Convener:*Yuichi Otsuka(Solar-Terrestrial Environment Laboratory, Nagoya University), Takuya Tsugawa(National Institute of Information and Communications Technology), Seiji Kawamura(National Institute of Information and Communications Technology)

5:15 PM - 6:30 PM

[PEM16-P12] Small-scale magnetic fluctuations of lower atmospheric origin as observed by low Earth orbit satellites ~ Identification of lower atmospheric phenomena ~

*Tadashi Aoyama1, Toshihiko Iyemori1, Kunihito Nakanishi1 (1.Graduate School of Science, Kyoto University)

Keywords:ionospheric dynamo, field-aligned current, acoustic resonance, SWARM, CHAMP, magnetic ripple

We recently found small-scale (0.1~5 nT) magnetic fluctuations above the ionosphere in middle and low latitudes with period about 20-30 sec along the satellite orbit observed by the low Earth orbit satellites such as the CHAMP (2000~2009) or the SWARM (2013~) having precise magnetometer (resolution: 0.065 nT). We name these magnetic fluctuations the "Magnetic Ripples" (MRs). The magnetic fluctuations are perpendicular to geomagnetic main field. By comparing the magnetic fluctuations observed by two SWARM satellites at the same latitude, we could confirm that they are the manifestation of the spatial structure of small scale field-aligned currents along the satellite orbit. The amplitude of the MRs have local time, geographical and seasonal dependence, therefore we suppose that localized field-aligned currents are generated by the ionospheric E-layer dynamo driven by the atmospheric gravity waves propagated from lower atmosphere. Typhoons and volcanic eruptions are known to generate gravity waves, and we report the characteristic of the MRs probably generated by a volcanic eruption, typhoons, rain fronts etc.. We try to identify the lower atmospheric phenomena which cause the MRs.