Mechanism of the energy balance non-closure associated with eddy covariance fluxes

• Project/Area Number: 19510020
• Research Category: Grant-in-Aid for Scientific Research (C)
• Allocation Type: Single-year Grants
• Section: 一般
• Research Field: Environmental dynamic analysis
• Research Institution: Hokkaido University
• Principal Investigator: WATANABE Tsutomu Hokkaido University, 低温科学研究所, 教授 (60353918)
• 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)
• Project Period (FY): 2007 – 2009
• Project Status: Completed (Fiscal Year 2009)
• Budget Amount: ¥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)
• 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

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.

Research Products

• [Journal Article] LES study on the structure of coherent eddies inducing predominant perturbations in velocities in the roughness sublayer over plant canopies (2009)
  • Author(s): Watanabe, T.
  • Journal Title: Journal of the Meteorological Society of Japan Vol. 87 Pages: 39-56
  • NAID: 110007122641
  • Peer Reviewed
• [Journal Article] 林床におけるCO_2放出フラックスの変動特性に関する研究 (2009)
  • Author(s): 溝口康子
  • Journal Title: 森林総合研究所報告 Vol. 8, No. 1 Pages: 1-50
  • Peer Reviewed
• [Journal Article] A review of tower flux observation sites in Asia (2009)
  • Author(s): Mizoguchi, Y., A. Miyata, Y. Ohtani, R. Hirata, S. Yuta
  • Journal Title: Journal of Forest Research Vol. 14 Pages: 1-9
  • NAID: 10029317090
  • Peer Reviewed
• [Journal Article] LES study on the structure of coherent eddies inducing predominant perturbations in velocities in the roughness sublayer over plant canopies (2009)
  • Author(s): T. Watanabe
  • Journal Title: Journal of the meteorological society of Japan 87 Pages: 39-56
  • NAID: 110007122641
  • Peer Reviewed
• [Journal Article] 植物群落内外の流れのLES (2008)
  • Author(s): 渡辺力
  • Journal Title: 気象研究ノート 219巻 Pages: 37-54
• [Presentation] 日中の接地層におけるスカラー相似性を崩す要因? (2009)
  • Author(s): 渡辺力
  • Organizer: 低温研共同研究集会「様々な土地被覆の大気境界層過程に関する研究集会」
  • Place of Presentation: 札幌
  • Year and Date: 2009-03-17
• [Presentation] 植生-大気相互作用の観測とモデリングにおける問題 (2008)
  • Author(s): 渡辺力
  • Organizer: 第6回水文・水資源学会セミナー
  • Place of Presentation: 東京
  • Year and Date: 2008-07-03
• [Presentation] 植生-大気相互作用の観測とモデリングにおける問題 (2008)
  • Author(s): 渡辺力
  • Organizer: 第6回水文・水資源学会セミナー
  • Place of Presentation: 東京・東大弥生講堂
  • Year and Date: 2008-07-03
• [Presentation] 農薬ドリフト研究へのLESの利用 (2007)
  • Author(s): 渡辺力・井上君夫
  • Organizer: 日本農業気象学会北海道支部大会
  • Place of Presentation: 帯広
  • Year and Date: 2007-11-28
• [Presentation] 農薬ドリフト研究へのLESの利用 (2007)
  • Author(s): 渡辺 力
  • Organizer: 日本農業気象学会北海道支部2007年大会
  • Place of Presentation: とからプラザ(帯広)
  • Year and Date: 2007-11-28
• [Presentation] フラックス輸送に寄与する渦の姿と観測上の問題点 (2007)
  • Author(s): 渡辺力
  • Organizer: 風に関するシンポジウム
  • Place of Presentation: 東京
  • Year and Date: 2007-06-21
• [Presentation] フラックス輸送に寄与する渦の姿と観測上の問題点 (2007)
  • Author(s): 渡辺 力
  • Organizer: 風に関するシンポジウム
  • Place of Presentation: 東京大学弥生講堂(東京)
  • Year and Date: 2007-06-21