| Project/Area Number |
11201205
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| Research Category |
Grant-in-Aid for Scientific Research on Priority Areas (B)
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| Allocation Type | Single-year Grants |
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| Review Section |
Science and Engineering
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| Research Institution | Kyoto University |
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Principal Investigator |
ISHIKAWA Hirohiko Kyoto Univ., Disaster Prevention Res. Inst, Associate Professor, 防災研究所, 助教授 (60263159)
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| Co-Investigator(Kenkyū-buntansha) |
TAMAGAWA Ichiro Gifu Univ., Faculty of Eng., Associate Professor, 工学部, 助教授 (40273198)
塚本 修 岡山大学, 理学部, 教授 (40027298)
HAYASH Taiichi Kyoto Univ., Disaster Prevention Res. Inst., Associate Professor, 防災研究所, 助教授 (10111981)
HAGINOYA Shigenori Meteorological Research Institute, Physical Meteorology Research Department, 物理気象研究部, 主任研究官
KUWAGATA Tsuneo National Institute for Agro-Environmental Sciences, Agro-Meteorology Group, 地球環境部気象研究グループ, 主任研究官
TANAKA Kenji Kumamoto Univ., Faculty of Eng., Research Assistant, 工学部, 助手 (30315288)
植田 洋匡 京都大学, 防災研究所, 助教授 (70026186)
寺尾 徹 京都大学, 防災研究所, 助手 (30303910)
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| Project Period (FY) |
1999 – 2001
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| Project Status |
Completed (Fiscal Year 2002)
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| Budget Amount *help |
¥31,400,000 (Direct Cost: ¥31,400,000)
Fiscal Year 2001: ¥7,800,000 (Direct Cost: ¥7,800,000)
Fiscal Year 2000: ¥10,700,000 (Direct Cost: ¥10,700,000)
Fiscal Year 1999: ¥12,900,000 (Direct Cost: ¥12,900,000)
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| Keywords | Land surface-atmosphere interaction / Tibetan Plateau / Asian Monsoon / Atmospheric boundary layer / Heat and Water circulation / Turbulent transport / GAME / GEWEX / 地表面熱吸収 / 気候変動 / 地表面熱収支 |
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| Research Abstract |
The exchange of sensible and latent heat at the interface of atmosphere and the land surface was directly measured by eddy correlation method based on the measurement of atmospheric turbulence. Four flux sites, Amdo, MS3478, BJ(Naqu) and MS3637, were set up and the measurements were conducted during the IOP. In these sites the radiation budget, soil surface temperature, soil temperature profile, soil moisture profile and soil heat flux were also measured. These measured results serve as a consistent database to study land surface-atmosphere interaction.
With this results both diurnal and seasonal changes of the sensible and latent heat flux were clearly detected at Amdo where the longest and continuous data was obtained. Before the monsoon the ground surface was very dry and the diurnal change of the surface temperature was as large as 50 degree Celsius. The latent heat flux was very small and the sensible heat flux was dominant As the ground surface became wet after the onset of monsoo
… More
n, the latent heat flux increased and the sensible heat flux decreased. This change was in harmony with the decease of the ground surface temperature. Typical diurnal change of fluxes was also obtained for pre-monsoon, mid-monsoon and late-monsoon periods (Ishikawa et al, 1999). Tsukamoto et al(2001) compared the flux observation at four sites. They also show that the sensible heat flux controls the development of the depth of mixing layer.
At these flux sites, Tanaka et al. (2001a, 2001c), Miyazaki et al. (2001), Wang (2001) and Kim et al. (2001) reported fluximbalance'. They suggest that many factors are responsible for the imbalance. They also stress the importance of mean vertical motion of air mass which may be induced by small scale organized disturbances. Tanaka et al. (2001c) give a discussion on the measurement of soil heat flux. They roughly estimated the surface soil heat flux needed to melt the permafrost and to heat the soil layer from April to June using the soil moisture and temperature data. The required surface heat flux was about 30W/m^2 on average, which was greater than that measured by soil heat plate. Tanaka et al. (2001b) examined the performance of a heat plate numerically and suggested that some correction is necessary to the soil heat flux. The surface imbalance problem has not yet been resolved. This severely limits the usefulness of the observed flux data.
The western Tibet is a region where the distribution of meteorological station is very sparse. Two automated meteorological stations were set up at Gaize and Shichuanhe and the continuous measurement of surface boundary layer and some soil variables has been conducted. Haginoya(2001) reported the surface meteorology and fluxes estimated by the Bowen ratio method at these sites. Xu and Haginoya(2001) estimated the monthly averaged surface fluxes at fourteen Tibetan sites using conventional surface observation data. At Amdo site PBL tower observation has been continued after the IOP. Tanaka et al. (2001d) compute the bulk transfer coefficient for the sensible heat flux at the site by comparing the tower data with turbulent flux during IOP. The coefficient is obtained as a function of the bulk Richardson number. With this coefficient and the continued tower observation data they computed the sensible heat flux until July 2000. The data suggests the strong inter annual variation, even the tower observation failed in Spring, when the sensible heat flux is largest in the year. Less
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