Grant-in-Aid for international Scientific Research
|Allocation Type||Single-year Grants |
|Research Institution||Nagoya University |
YUMOTO Kyofumi Solar-Terrestrial Environment Lab., Nagoya Univ.Associate professor, 太陽地球環境研究所, 助教授 (20125686)
OLSON J.v. Geophysical Institute, Univ.of Alaska Fairbanks professor, 地球物理研究所, 教授
AKASOFU S-i. Geophysical Institute, Univ.of Alaska Fairbanks Director, 地球物理研究所, 所長
KAMEI Toyohisa Faculty of Science, Kyoto Univ.Assistant, 理学部, 助手 (10233967)
SAKURAI Tooru Faculty of Engineering, Tokai Univ.professor, 工学部, 教授 (00004416)
TANAKA Yoshihito Faculty of Education, Yamaguchi Univ.professor, 教育学部, 教授 (30023675)
SHIOKAWA Kazuo Solar-Terrestrial Environment Lab., Nagoya Univ.Assistant, 太陽地球環境研究所, 助手 (80226092)
NISHINO Masanori Solar-Terrestrial Environment Lab., Nagoya Univ.Lecturer, 太陽地球環境研究所, 講師 (70023679)
SUN Wei アラスカ大学, 地球物理研究所, 助手
OSBORNE D.L. アラスカ大学, 地球物理研究所, 主任技師
國分 征 名古屋大学, 太陽地球環境研究所, 所長 (00011502)
高橋 主衛 名古屋大学, 太陽地球環境研究所, 助教授 (70252294)
林 幹治 東京大学, 理学部, 助教授 (60011730)
|Project Period (FY)
1994 – 1995
Completed(Fiscal Year 1995)
|Budget Amount *help
¥8,800,000 (Direct Cost : ¥8,800,000)
Fiscal Year 1995 : ¥4,900,000 (Direct Cost : ¥4,900,000)
Fiscal Year 1994 : ¥3,900,000 (Direct Cost : ¥3,900,000)
|Keywords||Auroral substorm / Electro- magnetic variations / Transfer process / Conjugate observation / Global variation / ULF waves / Alaska / Macquarie Isl. / North / south asymmetry / 多点観測網 / 磁気共役観測 / エネルギー輸送|
In order to clarify the conjugacy of electromagnetic disturbances at auroral latitudes, and transfer (propagation) proceses of these disturbances from higher to equatorial latitudes, and to understand global variations of the magnetospheric phenomena, we had carried out the magnetic conjugate observations in Alaska and Macquarie Island. In this year we did the following overseas field research and collaborative study :
(1) We continued to observe auroral substorms at Kotzebue in Alaska by means of magnetometer, atmospheric electric field instrument, all-sky TV camera, and photometer.
Magnetic ad optical observations at the magnetic conjugate points of Kotzebue, i.e.Macquarie Island, were also carried out in cooperation with Australian Antarctic Division.
(3)Auroral observations at Tixie in Siberia, and in Canada were done in cooperations with IKFIA of Russian Academy of Science and GRL,Univ.of Tokyo. All-sky TV camera was installed at Zhigansk in Yakutsk to investigate the longitudinal ex
pansion of auroral substorm.
(4) Magnetic observation at Koror near the magnetic equator was continued to study the relationships between eastward auroral electrojet and equatorial electrojet in daytime.
(5) Imaging Riometer observation was also continued to study the daytime aurora in the cusp region.
(6) The principal investigator visited Institute of Earth Physics, Russian Academy of Science, to start the collaborative data analysis, to summarize the results from this project, and to present the papers in future.
From these collaborative studies, the following results were obtained.
[I] Variations in the 10-min.to 1-hr period range of the eastward auroral electrojet are found to be identified in those of the dayside equatorial electrojet. The eastward auroral and equatorial electrojets may be connected by DP-type ionospheric currents.
[II] North/south hemisphere asymmetry of sc/si disturbances appears at low latitudes. The amplitude ranges at low-latitude conjugate points in the summer hemisphere are about twice as wide as those in the winter hemisphere. This can be interpreted by invoking an asymmetry in ionospheric currents driven by the DP field, i.e invoking enhanced ionospheric conductivities in the summer hemisphere.
[III] Field-line oscillations in the Pc3-5 range observed at the high and low-latitude conjugate pairs are found to show the northern/southern asymmetry and seasonal variations of amplitudes. These observational facts can not explained by using the existing theories.
These results give a clue to the unresolved propagation (transfer) mechanisms of electromagnetic disturbances from high latitude to the equatorial latitude. Less