Japan Geoscience Union Meeting 2015

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International Session (Oral)

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

[P-EM06] Mesosphere-Thermosphere-Ionosphere Coupling in the Earth's Atmosphere

Tue. May 26, 2015 4:15 PM - 6:00 PM A01 (APA HOTEL&RESORT TOKYO BAY MAKUHARI)

Convener:*Huixin Liu(Earth and Planetary Science Division, Kyushu University SERC, Kyushu University), Yuichi Otsuka(Solar-Terrestrial Environment Laboratory, Nagoya University), Libo Liu(Institute of Geology and Geophysics, Chinese Academy of Sciences), Atsuki Shinbori(Research Institute for Sustainable Humanosphere (RISH), Kyoto University), Chair:Yuichi Otsuka(Solar-Terrestrial Environment Laboratory, Nagoya University)

5:30 PM - 5:45 PM

[PEM06-05] Temperature trend of electron and ion with plasma density in middle and low latitude in the topside ionosphere

*Yoshihiro KAKINAMI1, Shigeto WATANABE2, Huixin Liu3 (1.Kochi University of Technology, 2.Hokkaido Information University, 3.Kyuhsu University)

Keywords:topside ionsophere, electron temperature, electron density, ion temperature, photoelectron, middle and low latitude

It is important to understand energy flow from electron to ion and neutral species because main heat source of ionospheric plasma is photoelectron created by solar EUV. First, electrons are heated by photoelectrons, then heated electrons reduce their energy through the Column collision with ions. Finally, ions are cooled by inelastic collision with neutral species. Temperatures of electron (Te), ion (Ti) and neutral species (Tn) get close to each other during night time due to lack of significant heat source. Heating rate of electron by photoelectron is proportion to ambient plasma density while cooling rate of electron is proportion to square of the plasma density. Therefore, Te decreases with increase of electron density (Ne) in general. However, some satellite results show Te increases with increase of Ne when Ne is high enough (more than about 106 cm-3). To understand the unexpected Te, it is also important to know Ti variation because ion plays as a heat sink of electron. In this paper, we summarized correlation of Ne with Te and Ti observed by HINOTORI, CHAMP and ROCSAT-1 in the topside ionosphere. Since these satellites did not observe Te and Ti simultaneously, Te, Ti and Ne measured with the incoherent scatter radars at Jicamaruca and Millstone Hill are also shown. Using these data, we discuss possible cause of unexpected high Te in high Ne region.