| Project/Area Number |
17540400
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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 | National Institute of Polar Research |
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Principal Investigator |
DOI Koichiro National Institute of Polar Research, Division for Research and Education, Associate Professor (80290873)
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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 |
¥3,550,000 (Direct Cost: ¥3,400,000、Indirect Cost: ¥150,000)
Fiscal Year 2007: ¥650,000 (Direct Cost: ¥500,000、Indirect Cost: ¥150,000)
Fiscal Year 2006: ¥1,400,000 (Direct Cost: ¥1,400,000)
Fiscal Year 2005: ¥1,500,000 (Direct Cost: ¥1,500,000)
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| Keywords | ICESat laser altimeter / Superconducting gravimeter / Ice surface topographic height / Antarctic ice sheet mass change / Gravity residual / Syowa Station / 南極 / 氷床表面高度変動 / 重力トレンド / レーザー高度計 / 干渉合成開口レーダー / 非潮汐海水位変化 / 海水位トレンド / 干渉合成開ロレーダー / 氷床変動 / 重力変化 / 海水位変動 |
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| Research Abstract |
At first, gravity residual was obtained by extracting tidal signals, effect of atmospheric pressure change, effect of polar motion and instrumental drift from original data after 2003 through 2006 of superconducting gravimeter (SG) at Syowa Station, Antarctica.
In the processing, it was found that instrumental drift larger than 200 micro-Gal per year of SG CT#043 can be approximated by a decaying exponential function of first order. Effect of non-tidal change of ocean on gravity observation was also investigated.
On the other hand, measurement by laser altimeter which is equipped with a satellite ICESat started in February 2003, and we used GLAl2 product of release 28 observed at 11 acquisition periods until April 2007. We made Antarctic ice sheet topographies from altimetry data of the 11 acquisition periods and estimated temporal volume changes of ice sheet from the topographies of the 11 acquisition periods. The estimated volume changes were reduced to ice sheet mass changes by multiplying surface ice density obtained from in-situ measurements on Antarctic ice sheet.
Gravity changes at Syowa Station induced by Antarctic ice sheet mass changes can be calculated from temporal ice sheet mass changes over Antarctic continent. We calculated temporal gravity changes from the temporal mass changes over Antarctic continent estimated from the 11 acquisition periods data and compared the expected gravity changes caused by the ice sheet mass changes with the observed gravity residuals. Temporal changes of the observed gravity residuals did not so resemble the expected gravity changes in phasis and magnitude. The differences may be caused by estimation error in ice sheet heights of coastal region in the vicinity of Syowa Station. In the future, we intend to improve the way to estimate heights at grid points in sloping region such as coastal area of Antarctica.
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