TY - JOUR
T1 - Coordinated Akebono and EISCAT observations of suprathermal ion outflows in the nightside inverted-V region
AU - Yoshida, N.
AU - Watanabe, S.
AU - Fukunishi, H.
AU - Sakanoi, T.
AU - Mukai, T.
AU - Hayakawa, H.
AU - Matsuoka, A.
AU - Kasahara, Y.
AU - Fujii, R.
AU - Nozawa, S.
AU - Ogawa, Y.
N1 - Funding Information:
This work has been carried out by the use of Akebono SDB released from the Institute of Space and Astronautical Science (ISAS), the sponsoring agency of the Akebono mission, with important support from the National Institute of Polar Research (NIPR) and the Canadian Space Agency (CSA). We are indebted to the director and staff of EISCAT for operating the facility and supplying the data. EISCAT is an international Association supported by Finland (SA), France (CNRS), the Federal Republic of Germany (MPG), Japan (NIPR), Norway (NFR), Sweden (NFR) and the United Kingdom (PPARC). This study was supported in part by a Grant-in-aid for International Scientific Research (09044074) and by Grants-in-aid for Scientific Research A (08304030) and B (08454135) by the Ministry of Education, Science, Sports and Culture, Japan. We are most grateful to the Japanese EISCAT Science Group for EISCAT data processing. We are much indebted to the Geophysical Research Division of Finnish Meteorological Institute for the panchromatic all-sky imager operation including at Muonio site. We wish to express our gratitude to Data Analysis Center for Geomagnetism and Space Magnetism Graduate School of Science, Kyoto University, Japan for the supply of the Geomagnetic field data at Tromsø station.
PY - 2000/4/1
Y1 - 2000/4/1
N2 - We have investigated ion outflows observed by the Akebono satellite and the EISCAT radar in the nightside auroral region on February 16, 1993. The Akebono satellite at about 7000 km altitude observed the region of suprathermal ion outflows and inverted-V type electron precipitation alternately with a horizontal separation of 70-150 km at the ionospheric level. These two regions corresponded to the upward and downward field-aligned current region, respectively, and intense ELF waves were observed in the ion outflow region. From the EISCAT VHF radar observation (Common Program 7 mode), it has been suggested that the ion outflow region and the enhanced electron temperature region were aligned along geomagnetic field lines with vertical and horizontal separations of 200-400 and 70-80 km, respectively and these two regions convected equatorward across the EISCAT radar at Tromsø site. Based on these results, we propose a model for this ion outflow as follows. In the nightside auroral region, downward FAC regions exist near the edge of the inverted-V type electron precipitation regions. ELF waves are excited probably by a plasma instability due to the upward thermal electron beam carrying the downward FACs, and these ELF waves cause transverse ion heating at the top of the ionosphere. The produced ion conies contribute significantly to ion outflow.
AB - We have investigated ion outflows observed by the Akebono satellite and the EISCAT radar in the nightside auroral region on February 16, 1993. The Akebono satellite at about 7000 km altitude observed the region of suprathermal ion outflows and inverted-V type electron precipitation alternately with a horizontal separation of 70-150 km at the ionospheric level. These two regions corresponded to the upward and downward field-aligned current region, respectively, and intense ELF waves were observed in the ion outflow region. From the EISCAT VHF radar observation (Common Program 7 mode), it has been suggested that the ion outflow region and the enhanced electron temperature region were aligned along geomagnetic field lines with vertical and horizontal separations of 200-400 and 70-80 km, respectively and these two regions convected equatorward across the EISCAT radar at Tromsø site. Based on these results, we propose a model for this ion outflow as follows. In the nightside auroral region, downward FAC regions exist near the edge of the inverted-V type electron precipitation regions. ELF waves are excited probably by a plasma instability due to the upward thermal electron beam carrying the downward FACs, and these ELF waves cause transverse ion heating at the top of the ionosphere. The produced ion conies contribute significantly to ion outflow.
KW - Alternations
KW - Elf wave
KW - Ion outflow
KW - Transversely acceleration
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U2 - 10.1016/S1364-6826(00)00012-2
DO - 10.1016/S1364-6826(00)00012-2
M3 - Article
AN - SCOPUS:6744243265
VL - 62
SP - 449
EP - 465
JO - Journal of Atmospheric and Solar-Terrestrial Physics
JF - Journal of Atmospheric and Solar-Terrestrial Physics
SN - 1364-6826
IS - 6
ER -