Technical development of precised determination of the geoid and the field variations in the Northwest Pacific from dedicated satellite gravity data
| Project/Area Number |
17540402
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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 |
Solid earth and planetary physics
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| Research Institution | Geographical Survey Institute, Geography and Crustal Dynamics Research Center |
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Principal Investigator |
KUROISHI Yuki Geographical Survey Institute, Geography and Crustal Dynamics Research Center, 宇宙測地研究室, Head (30370810)
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| Project Period (FY) |
2005 – 2007
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| Project Status |
Completed (Fiscal Year 2007)
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| Budget Amount *help |
¥3,310,000 (Direct Cost: ¥3,100,000、Indirect Cost: ¥210,000)
Fiscal Year 2007: ¥910,000 (Direct Cost: ¥700,000、Indirect Cost: ¥210,000)
Fiscal Year 2006: ¥1,000,000 (Direct Cost: ¥1,000,000)
Fiscal Year 2005: ¥1,400,000 (Direct Cost: ¥1,400,000)
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| Keywords | Geodesy / Satellite / Gravity / Geoid |
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| Research Abstract |
We developed a method to recover the global gravity field from a dedicated satellite gravity mission, GRACE. First, accelerometer data are calibrated for scales and biases by fitting dynamically calculated orbits to GPS-determined precise orbits. Then, the inter-satellite range-rate data together with the accelerometer data calibrated and attitude data are used in dynamic orbit integrations to recover the gravity field in spherical harmonic representation. To reduce aliasing effects caused by short-term variations of the atmospheric and oceanic mass distribution, we introduce a global atmospheric mass distribution model and an assimilated baroclinic ocean and hydrological discharge model as geophysical models for correction. The method is applied for one year of GRACE data for 2005, yielding monthly mean global gravity field models. The annual average of the resulting models is combined with land and ship-borne gravity data in the Northwest Pacific and an altimetry-derived marine gravi
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ty model to obtain an improved gravity/geoid model for the region. In the combination, a semidiscrete two-dimensional wavelet analysis/recovery method is employed, taking the spatial wavelength signals of highest quality out of respective data sets. The comparison with GPS/leveling geoid undulations shows substantial improvement of the geoid model obtained over the previous one and reveals notably that such systematic errors at long wavelengths. that the previous model contains have been effectively removed. Discrepancies of the geoid model from the mean sea surface heights at tidal stations in isolated islands compare well with the differences of the sea surface dynamic heights (SSDH) in the Japan Sea, the Nansei Islands and the Izu Island chain from that of Tokyo Bay. The discrepancies show good agreement with SSDH features estimated from oceanographic observation, revealing the geoid model has accuracy within 10 cm. The geoid model is highly expected to serve as a reference to ocean dynamics study. Less
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Report
(4 results)
Research Products
(35 results)
