| Project/Area Number |
60840009
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| Research Category |
Grant-in-Aid for Developmental Scientific Research
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| Allocation Type | Single-year Grants |
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| Research Field |
気象・海洋・陸水学
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| Research Institution | College of Liberal Arts and Sciences, Okayama University |
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Principal Investigator |
OHTAKI Eiji College of Liberal Arts and Sciences, Okayama Univ., Professor, 教養部, 教授 (40033120)
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| Co-Investigator(Kenkyū-buntansha) |
日沼 篤二 リツー応用光学(株), 技術部
松井 哲司 アドバンストシステム(株), 技術部
MATSUI Tetsuji Advanced Systems Inc., Technical Expert
HINUMA Tokuji Applied Optics Inc., Technical Expert
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| Project Period (FY) |
1985 – 1986
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| Project Status |
Completed (Fiscal Year 1986)
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| Budget Amount *help |
¥4,600,000 (Direct Cost: ¥4,600,000)
Fiscal Year 1986: ¥1,300,000 (Direct Cost: ¥1,300,000)
Fiscal Year 1985: ¥3,300,000 (Direct Cost: ¥3,300,000)
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| Keywords | Carbon dioxide flux / Humidity flux / 渦相関法 / 炭酸ガス / 水蒸気 / 変動計 |
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| Research Abstract |
The accurate measurement of turbulent transport of carbon dioxide in the atmospheric surface layer has been expected to achieve deep understanding of the carbon dioxide - climate ploblem. The eddy correlation technique is the most promising one to measure turbulent transport of carbon dioxide. In order to investigate carbon dioxide transport by the eddy correlation technique, we developed the fast response instrument designed to measure simultaneous fluctuations of carbon dioxide and humidity. The measuring frequency is 30 Hz and the sensing path length is 20 cm. The noise is 0.3 ppm for carbon dioxide measurement and 0.01 g/kg for humidity measurement. The drift of the instrument is about 0.16 ppm/h and 0.01 g kg/h, respectively.
The instrument is applied to the field experiments under various surface conditions: stubble field, sea surface and vegetated fields. The wc-cospectra of vertical wind velocity and carbon dioxide fluctuations are calculated by Tukey's scheme in order to investigate the carbon dioxide transport processes. It is noted that the we-cospectra from the stubble field are confined to a narrow range of 0.02 to 0.1 Hz. The average values of turbulent transport of carbon dioxide are about -0.05 mg <m^(-2)s^(-1)> in the daytime and less than 0.05 mg <m^(-2)s^(-1)> in the nighttime. The raw values of turbulent transport of carbon dioxide over sea surface are negative of -0.05 to -0.17 mg <m^(-2)s^(-1)> .
Field experiments show that the present instrument is promising for flux measurements of carbon dioxide and humidity by the eddy correlation technique in conjunction with a sonic anemometer.
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