Browsing by Author "Ogawa, Yasunobu"
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- First Simultaneous Lidar Observations of Thermosphere-Ionosphere Fe and Na (TIFe and TINa) Layers at McMurdo (77.84 degrees S, 166.67 degrees E), Antarctica With Concurrent Measurements of Aurora Activity, Enhanced Ionization Layers, and Converging Electric FieldChu, Xinzhao; Nishimura, Yukitoshi; Xu, Zhonghua; Yu, Zhibin; Plane, John M. C.; Gardner, Chester S.; Ogawa, Yasunobu (2020-10-28)We report the first simultaneous, common-volume lidar observations of thermosphere-ionosphere Fe (TIFe) and Na (TINa) layers in Antarctica. We also report the observational discovery of nearly one-to-one correspondence between TIFe and aurora activity, enhanced ionization layers, and converging electric fields. Distinctive TIFe layers have a peak density of similar to 384 cm(-3) and the TIFe mixing ratio peaks around 123 km, similar to 5 times the mesospheric layer maximum. All evidence shows that Fe+ ion-neutralization is the major formation mechanism of TIFe layers. The TINa mixing ratio often exhibits a broad peak at TIFe altitudes, providing evidence for in situ production via Na+ neutralization. However, the tenuous TINa layers persist long beyond TIFe disappearance and reveal gravity wave perturbations, suggesting a dynamic background of neutral Na, but not Fe, above 110 km. The striking differences between distinct TIFe and diffuse TINa suggest differential transport between Fe and Na, possibly due to mass separation.
- Ground-based instruments of the PWING project to investigate dynamics of the inner magnetosphere at subauroral latitudes as a part of the ERG-ground coordinated observation networkShiokawa, Kazuo; Katoh, Yasuo; Hamaguchi, Yoshiyuki; Yamamoto, Yuka; Adachi, Takumi; Ozaki, Mitsunori; Oyama, Shin-Ichiro; Nosé, Masahito; Nagatsuma, Tsutomu; Tanaka, Yoshimasa; Otsuka, Yuichi; Miyoshi, Yoshizumi; Kataoka, Ryuho; Takagi, Yuki; Takeshita, Yuhei; Shinbori, Atsuki; Kurita, Satoshi; Hori, Tomoaki; Nishitani, Nozomu; Shinohara, Iku; Tsuchiya, Fuminori; Obana, Yuki; Suzuki, Shin; Takahashi, Naoko; Seki, Kanako; Kadokura, Akira; Hosokawa, Keisuke; Ogawa, Yasunobu; Connors, Martin; Ruohoniemi, J. Michael; Engebretson, Mark J.; Turunen, Esa; Ulich, Thomas; Manninen, Jyrki; Raita, Tero; Kero, Antti; Oksanen, Arto; Back, Marko; Kauristie, Kirsti; Mattanen, Jyrki; Baishev, Dmitry; Kurkin, Vladimir; Oinats, Alexey; Pashinin, Alexander; Vasilyev, Roman; Rakhmatulin, Ravil; Bristow, William A.; Karjala, Marty (2017-11-28)The plasmas (electrons and ions) in the inner magnetosphere have wide energy ranges from electron volts to mega-electron volts (MeV). These plasmas rotate around the Earth longitudinally due to the gradient and curvature of the geomagnetic field and by the co-rotation motion with timescales from several tens of hours to less than 10 min. They interact with plasma waves at frequencies of mHz to kHz mainly in the equatorial plane of the magnetosphere, obtain energies up to MeV, and are lost into the ionosphere. In order to provide the global distribution and quantitative evaluation of the dynamical variation of these plasmas and waves in the inner magnetosphere, the PWING project (study of dynamical variation of particles and waves in the inner magnetosphere using ground-based network observations, (http://www.isee.nagoya-u.ac.jp/dimr/PWING/) has been carried out since April 2016. This paper describes the stations and instrumentation of the PWING project. We operate all-sky airglow/aurora imagers, 64-Hz sampling induction magnetometers, 40-kHz sampling loop antennas, and 64-Hz sampling riometers at eight stations at subauroral latitudes (~ 60° geomagnetic latitude) in the northern hemisphere, as well as 100-Hz sampling EMCCD cameras at three stations. These stations are distributed longitudinally in Canada, Iceland, Finland, Russia, and Alaska to obtain the longitudinal distribution of plasmas and waves in the inner magnetosphere. This PWING longitudinal network has been developed as a part of the ERG (Arase)-ground coordinated observation network. The ERG (Arase) satellite was launched on December 20, 2016, and has been in full operation since March 2017. We will combine these ground network observations with the ERG (Arase) satellite and global modeling studies. These comprehensive datasets will contribute to the investigation of dynamical variation of particles and waves in the inner magnetosphere, which is one of the most important research topics in recent space physics, and the outcome of our research will improve safe and secure use of geospace around the Earth.