2003 Fiscal Year Final Research Report Summary
Numerical Study of Precession/Nutation Theory
| Project/Area Number |
12640245
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| Research Category |
Grant-in-Aid for Scientific Research (C)
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| Allocation Type | Single-year Grants |
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| Section | 一般 |
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| Research Field |
Astronomy
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| Research Institution | National Astronomical Observatory |
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Principal Investigator |
FUKUSHIMA Toshio National Astronomical Observatory, Public Relation Center, Professor, 天文情報公開センター, 教授 (70231735)
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| Project Period (FY) |
2000 – 2003
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| Keywords | Precession / Nutation / VLBI / Planetary Precession / Lunisolar Precession / Geodesic Precession / Nonlinear Harmonic Analysis / Dynamical Flattening |
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| Research Abstract |
We developed a new nutation theory of a nonrigid Earth SF2001, based on the RDAN as that for a rigid Earth, adopting the SOS model of nonrigidity, and fitted to the VLBI observation data for the period 1979-2000 (Shirai and Fukushima 2001). As its by-products, we obtained the precise estimates of the dynamical flattening of the Earth and some other basic geophysical constants.
Next, we created a new method of nonlinear harmonic analysis (Harada and Fukushima 2003), which enables us to decompose a complicated time series into a quadratic polynomial and arbitrary number of waves of unknown frequencies. Applying this powerful technique to the direction vector of the orbital angular momentum of the Earth-Moon barycenter around the Sun in the latest lunar/planetary ephemeris, DE405, we extracted the secular variation of the two angles specifying the ecliptic(Harada and Fukushima 2004). This formual, called HF2003 is the latest and most precise determination of the planetary precession.
Finally, we obtained a high precision estimate of the secular variation of the Earth's figure axis in space from the above VLBI data by removing the periodic effects with the aid of the SF2001 nutation theory and by separating the effects of planetary precession with the usage of HF2003 planetary precession formula (Fukushima 2003).
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