@article{ca4ab194eed34f4fb847245e75127f9b,
title = "Longitudinal Structure of Oxygen Torus in the Inner Magnetosphere: Simultaneous Observations by Arase and Van Allen Probe A",
abstract = "Simultaneous observations of the magnetic field and plasma waves made by the Arase and Van Allen Probe A satellites at different magnetic local time (MLT) enable us to deduce the longitudinal structure of an oxygen torus for the first time. During 04:00–07:10 UT on 24 April 2017, Arase flew from L = 6.2 to 2.0 in the morning sector and detected an enhancement of the average plasma mass up to ~3.5 amu around L = 4.9–5.2 and MLT = 5.0 hr, implying that the plasma consists of approximately 15% O+ ions. Probe A moved outbound from L = 2.0 to 6.2 in the afternoon sector during 04:10–07:30 UT and observed no clear enhancements in the average plasma mass. For this event, the O+ density enhancement in the inner magnetosphere (i.e., oxygen torus) does not extend over all MLT but is skewed toward the dawn, being described more precisely as a crescent-shaped torus or a pinched torus.",
keywords = "Arase satellite, Van Allen Probes satellite, geomagnetic storm, inner magnetosphere, oxygen torus, simultaneous observation",
author = "M. Nos{\'e} and A. Matsuoka and A. Kumamoto and Y. Kasahara and J. Goldstein and M. Teramoto and F. Tsuchiya and S. Matsuda and M. Shoji and S. Imajo and S. Oimatsu and K. Yamamoto and Y. Obana and R. Nomura and A. Fujimoto and I. Shinohara and Y. Miyoshi and Kurth, {W. S.} and Kletzing, {C. A.} and Smith, {C. W.} and MacDowall, {R. J.}",
note = "Funding Information: Science data of the ERG (Arase) satellite were obtained from the ERG Science Center operated by ISAS/JAXA and ISEE/Nagoya University (https://ergsc.isee.nagoya-u.ac.jp/index.shtml.en). The Arase satellite data will be publicly available via ERG Science Center on a project-agreed schedule. The present study analyzed the MGF L2_v01.01 data, the PWE-OFA L2_v02_01 data, and the PWE-HFA L2_v01_01 data. The Van Allen Probes/EMFISIS data are available at http://emfisis.physics.uiowa.edu. The present study used the EMFISIS L3_v1.6.1 data. The electron number density data at Probe A position were obtained on request to W. S. Kurth and provided with L4_v1.5.15. The SYM-H index is provided by the World Data Center for Geomagnetism, Kyoto, and is available at http://wdc.kugi.kyoto-u.ac.jp. Geomagnetic field by the IGRF-12 and T89 models is calculated with GEOPACK routines developed by N. A. Tsyganenko and coded by H. Korth. This study is supported by the Japan Society for the Promotion of Science (JSPS), Grant-in-Aid for Scientific Research (B) (grant 16H04057), Challenging Research (Pioneering) (grant 17K18804), and Grant-in-Aid for Specially Promoted Research (grant 16H06286). Y. M. is supported by the Japan Society for the Promotion of Science (JSPS), Grant-in-Aid for Scientific Research on Innovative Areas (grant 15H05815). The work at the University of Iowa was performed through JHU/APL contract 921647 under NASA Prime contract NAS5-01072. Funding Information: Science data of the ERG (Arase) satellite were obtained from the ERG Science Center operated by ISAS/JAXA and ISEE/Nagoya University (https://ergsc. isee.nagoya-u.ac.jp/index.shtml.en). The Arase satellite data will be publicly available via ERG Science Center on a project-agreed schedule. The present study analyzed the MGF L2_v01.01 data, the PWE-OFA L2_v02_01 data, and the PWE-HFA L2_v01_01 data. The Van Allen Probes/EMFISIS data are available at http://emfisis.physics.uiowa.edu. The present study used the EMFISIS L3_v1.6.1 data. The electron number density data at Probe A position were obtained on request to W. S. Kurth and provided with L4_v1.5.15. The SYM-H index is provided by the World Data Center for Geomagnetism, Kyoto, and is available at http://wdc.kugi.kyoto-u.ac. jp. Geomagnetic field by the IGRF-12 and T89 models is calculated with GEOPACK routines developed by N. A. Tsyganenko and coded by H. Korth. This study is supported by the Japan Society for the Promotion of Science (JSPS), Grant-in-Aid for Scientific Research (B) (grant 16H04057), Challenging Research (Pioneering) (grant 17K18804), and Grant-in-Aid for Specially Promoted Research (grant 16H06286). Y. M. is supported by the Japan Society for the Promotion of Science (JSPS), Grant-in-Aid for Scientific Research on Innovative Areas (grant 15H05815). The work at the University of Iowa was performed through JHU/APL contract 921647 under NASA Prime contract NAS5-01072.",
year = "2018",
month = oct,
day = "16",
doi = "10.1029/2018GL080122",
language = "English",
volume = "45",
pages = "10,177--10,184",
journal = "Geophysical Research Letters",
issn = "0094-8276",
publisher = "American Geophysical Union",
number = "19",
}