| Project/Area Number |
61302013
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| Research Category |
Grant-in-Aid for Co-operative Research (A)
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| Allocation Type | Single-year Grants |
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| Research Field |
Astronomy
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| Research Institution | International Latitude Observatory |
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Principal Investigator |
OKAMOT Isao International Latitude Observatory, 地球物理観測研究部, 課長 (90088782)
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| Co-Investigator(Kenkyū-buntansha) |
SASAO Tetsuo International Latitude Observatory, 極運動研究部, 課長 (20000177)
OKUBO Shuhei University of Tokyo, Earthguake Research Institute, 地震研究所, 助手 (30152078)
WAKO Yasujiro International Latitude Observatory, 極運動研究部, 部長 (40000161)
YONEYAMA Tadaoki Toyo University, Natural Science Laboratory, 文学部, 助教授 (00120353)
TOKOYAMA Koichi International Latitude Observatory, 極運動研究部, 課長 (10088784)
海野 和三郎 近畿大学, 理工学総合研究所, 教授 (30011414)
中嶋 浩一 一橋大学, 経済学部, 教授 (30012876)
青木 信仰 東京大学, 東京天文台・天文時部, 教授 (90012799)
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| Project Period (FY) |
1986 – 1987
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| Project Status |
Completed (Fiscal Year 1987)
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| Budget Amount *help |
¥8,700,000 (Direct Cost: ¥8,700,000)
Fiscal Year 1987: ¥3,700,000 (Direct Cost: ¥3,700,000)
Fiscal Year 1986: ¥5,000,000 (Direct Cost: ¥5,000,000)
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| Keywords | Astrometry / Earth rotation / Variations of rotational velocity / Chandler wobble / Chaos / Time series analisis / 極運動 / 統計解釈 / 地球物理学 |
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| Research Abstract |
1. The means of the Earth rotation study completely shifted from the optical observations to the VLBI observations. The investigators in the present Grant-in Aid commensed IRIS-P Network VLBI observations and are now producing high quality data of the Earth rotation. They are also persuing a full-scale VLBI system VERA (VLBI for the Earth Rotation study and Astrometry) in both sides of hardware and software.
2. The chaos analysis of the IPMS data were attempted for the purpose of detecting strange attractor, and the fractal dimension of polar motion is estimated to be 2.8-3.0. This means that polar motion is presented as a dynamical system of at most three variablis. The variation of the annual polar motion was shown to be apparent variation influenced by the nonlinear Chandler wobble, it being neither observational errors nor the variation of the actual excitation pole.
3. The code constructed for estimating the effective atmospheric angular momentum functions and the atmospheric excitation function from the atmospheric data supplied by the Japan Meteorological Agency promoted the study of the variations of the Earth rotation due to atmospheric effects.
4. Recent observational results due to VLBI's, superconducting gravimeters and strainmeters are now revealing the discrepancies of nutation and diurnal Earth tide from the theoretical model. It is shown that these discrepancies are reflections of the characteristics of the coupling between the fluid core and the mantle in the fluid core resonance phenomena. The significance of this line of research in the deep interior dynamics is pointed out.
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