Mechanism of the energy balance non-closure associated with eddy covariance fluxes
| Project/Area Number |
19510020
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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 |
Environmental dynamic analysis
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| Research Institution | Hokkaido University |
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Principal Investigator |
WATANABE Tsutomu Hokkaido University, 低温科学研究所, 教授 (60353918)
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| Co-Investigator(Kenkyū-buntansha) |
MIZOGUCHI Yasuko 独立行政法人森林総合研究所, 北海道支所, 主任研究員 (90353870)
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| Project Period (FY) |
2007 – 2009
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| Project Status |
Completed (Fiscal Year 2009)
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| Budget Amount *help |
¥3,510,000 (Direct Cost: ¥2,700,000、Indirect Cost: ¥810,000)
Fiscal Year 2009: ¥910,000 (Direct Cost: ¥700,000、Indirect Cost: ¥210,000)
Fiscal Year 2008: ¥1,300,000 (Direct Cost: ¥1,000,000、Indirect Cost: ¥300,000)
Fiscal Year 2007: ¥1,300,000 (Direct Cost: ¥1,000,000、Indirect Cost: ¥300,000)
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| Keywords | フラックス / 渦相関法 / 熱収支 / インバランス / タワー観測 / 数値流体シミュレーション / LES |
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| Research Abstract |
Undermeasure of the sensible and latent heat fluxes by the eddy covariance method is a world-wide common problem among the flux-monitoring tower sites. Analysis of a dataset from a broadleaf forest site in Kawagoe (Japan) revealed that significant undermeasure tended to occur under the condition of large net radiation and low wind speed. Numerical fluid dynamics simulations run for such conditions indicated that a single-point eddy-covariance measurement does not capture the flux's low-frequency components associated with quasi-stationary convections of spatial scale as large as the boundary layer depth, and thus underestimates the total flux. Observed dissimilarity between temperature's and water-vapor's low-frequency fluctuations supports this idea because it is consistent with the simulation results showing that hot and dry air entrained at the top of the boundary layer reaches the height of flux measurements (near the bottom of the boundary layer) owing to the large-scale convection and causes out-of-phase fluctuations of low frequencies.
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Report
(4 results)
Research Products
(12 results)
