| Project/Area Number |
17201008
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| Research Category |
Grant-in-Aid for Scientific Research (A)
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| Allocation Type | Single-year Grants |
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| Section | 一般 |
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| Research Field |
Environmental dynamic analysis
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| Research Institution | Japan, Meteorological Research Institute |
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Principal Investigator |
MIKAMI Masao Japan, Meteorological Research Institute, Physical Met. Res. Division, 2nd Research Labo, Head of 2nd Research Labo. (60354510)
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| Co-Investigator(Kenkyū-buntansha) |
NAGASIMA Hideki Rissyo Univ., Dept. of Geo-Environmental Science, Part-time Instructor (10087570)
ISHIZUKA Masahide Kagawa Univ., Dept. of Engineering, Associate Professor (50324992)
YAMADA Yutaka RIKEN, Advanced Tech. Support Division, Senior technical Scientist (70392165)
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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 |
¥33,670,000 (Direct Cost: ¥25,900,000、Indirect Cost: ¥7,770,000)
Fiscal Year 2007: ¥7,800,000 (Direct Cost: ¥6,000,000、Indirect Cost: ¥1,800,000)
Fiscal Year 2006: ¥7,800,000 (Direct Cost: ¥6,000,000、Indirect Cost: ¥1,800,000)
Fiscal Year 2005: ¥18,070,000 (Direct Cost: ¥13,900,000、Indirect Cost: ¥4,170,000)
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| Keywords | dust / yellow sand / wind erosion / threshold friction velocity / soil moisture / 臨海摩擦速度 / 風送ダスト / 飛砂 / パーティクルカウンタ / 砂漠 / オーストラリア / 気象観測 / 気候 |
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| Research Abstract |
For understanding wind erosion process, we have made an intensive observation (IOP) in Australia Using this data, we compared and validated a heterogeneous saltation theory and made a quantitative discussion about saltation flux, including its size distribution and vertical profile, threshold friction velocity, and relation to soil surface moisture and soil structure. We also conducted a comparison experiment with newly developed sand particle counter and Sensit.
Intensive observation was conducted on the fallow wheat field at southeastern part of Australia during period 23 Feb. to 13 march in 2006. We have monitored 12 dust event during IOP and results were summarized as follows;
1) Saltation flux and its time variation, size distribution, and vertical structure were obtained. During IOP, one big event and 11 small events occurred and one big event amount for the most part of the total saltation flux during IOP.
2) The size distribution of saltation shows 2-peaks, one is coarse mode with
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maximum at 200 micron meters and the other with maximum of 80 micron meters. This confirmed the presence of two phase of saltation mode that shads heterogeneous saltation theory predicted. The finer mode is due to exponential profile of fine sand particle and the coarser mode is due to logarithmic profile of coarse sand particle.
3) We can determined saltation threshold friction velocity with objective analysis of SPC data. The results show that the size dependence of threshold friction velocity is not found.
4) We have monitored the suppression of dust emission flux due to formation of weak crust at the ground surface formed by weak precipitation.
5) We have compared saltation fluxes measured by SPC and Sensit under different wind speed in the field type wind tunnel The SPC indicate good linearity with increase of wind speed. On the other hand, Sensit data shws decrease of flux with increase of wind speed when wind speed is high. This will be due to the coincident loss of collision signal when the particle number which collide with Sensit, exceed some limit value. For this, SPC will be more available for monitoring strong dust event. Less
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