| Project/Area Number |
17540415
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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 |
Meteorology/Physical oceanography/Hydrology
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| Research Institution | Osaka Prefecture University |
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Principal Investigator |
OKAMOTO Ken'ichi Osaka Prefecture University, Graduate School of Engineering, Professor, 工学研究科, 教授 (90326273)
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| Co-Investigator(Kenkyū-buntansha) |
SHIGE Shoichi Osaka Prefecture University, Graduate School of Engineering, Assistant Professor, 工学研究科, 助手 (60344264)
牛尾 知雄 大阪府立大学, 工学研究科, 講師 (50332961)
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| Project Period (FY) |
2005 – 2006
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| Project Status |
Completed (Fiscal Year 2006)
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| Budget Amount *help |
¥2,800,000 (Direct Cost: ¥2,800,000)
Fiscal Year 2006: ¥1,000,000 (Direct Cost: ¥1,000,000)
Fiscal Year 2005: ¥1,800,000 (Direct Cost: ¥1,800,000)
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| Keywords | earth observation / climate change / rain / rain radar / satellite / ground clutter / scattering coefficient / antenna scan angle |
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| Research Abstract |
Spaceborne precipitation radar can observe rain rate quantitatively, and is the main sensor to observe rain from space.
Unfortunately when the antenna tries to cover a wider swath, the rain echo from the antenna mainlobe direction is sharply deteriorated due to the increase of the ground clutter from the antenna sidelobe direction.
This study, for the future spaceborne precipitation radars, aims at examining the feasibility of developing the algorithm that corrects the rain radar data when it is affected by the ground clutter from the antenna sidelobe direction.
During this research period, we compiled the database of scattering coefficients σ^0 of soil, vegetation and water surface in various conditions using the 35.5 GHz polarimetric scatterometer. We collected the data at different incidence angles and with different transmit-receive polarizations, while changing the moisture contents and surface roughness of the soil, the leaf area index values of vegetation and the wind speeds over t
… More
he water surface.
Based on the TRMM precipitation radar data at 13.8 GHz, we established a large rain model to simulate rain observation from space by the radar. By comparing with the rain rates of this model, we examined how much the observed rain rate is deteriorated by the effects of the sea surface clutter, which happens with the increase of the antenna scan angle. In the simulation, we used the ideal Gaussian type antenna pattern and the planar phased array antenna pattern of the actual TRMM precipitation radar. As a result, when we applied the latter antenna pattern, the correlation coefficients between the observed rain rates and the model rain rates were as high as 0.74 even though the antenna beam scan angle increases as large as 30 degrees, which is far larger than the actual TRMM scan angle of 17 degrees. We also worked on the evaluation of the effects of partial beam filling of rain
The results we obtained from our research has shown us a good possibility of larger antenna scan angles and also a good prospect in developing the algorithms to correct the deterioration of rain echo by the ground clutters. Less
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