1995 Fiscal Year Final Research Report Summary
DEVELOPMENT OF OPEN PATH METHANE SENSOR
| Project/Area Number |
06558076
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| Research Category |
Grant-in-Aid for Developmental Scientific Research (B)
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| Allocation Type | Single-year Grants |
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| Research Field |
Environmental dynamic analysis
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| Research Institution | OKAYAMA UNIVERSITY |
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Principal Investigator |
OHTAKI Eiji OKAYAMA UNIV.ENVIRON.SCI.AND TECH.PROFESSOR, 環境理工学部, 教授 (40033120)
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| Co-Investigator(Kenkyū-buntansha) |
TORIGOE Hiroshi ADVANET CO.LTD,RESEARCHER, 研究開発部, 研究員
SAZAKI Susumu ADVANET CO.LTD,PRINCIPAL RESEARCHER, 研究開発部, 主任研究員
TSUKAMOTO Osamu OKAYAMA UNIV.SCIENCE,ASSOC.PROFESSOR, 理学部, 助教授 (40027298)
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| Project Period (FY) |
1994 – 1995
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| Keywords | EDDY CORRELATION METHOD / AERODYNAMIC METHOD / METHANE / METHANE FLUX |
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| Research Abstract |
Methane is an important trace gas in the atmosphere because its high potential to absorb the outgoing longwave radiation. The absorbing potential is about 20 times that of carbon dioxide. It is well known that the methane concentration in the atmosphere is increasing. The major source of this increasing methane concentration has been assumed to be human activities associated with rice cultivation and animal husbandry. The eddy correlation technique is the most promising method to measure methane flux in the atmosphere. However, this technique requires a fast response and high resolution instrument for methane measurement.
A prototype fast response CH4 instrument with open sensing path is developed in the present study. Results of the laboratory and fild test are summarized as follows : (1) The sensitivity of the instrument is about 15.6 ppm per volt. The measuring frequency is 30 Hz. (2) The noise-limited sensitivity is about 0.6 ppm peak-to-peak in CH4 concentration. (3) The sensitivity is practically invariant with a possible change in the adjustment of the optical system. (4) Preliminary test shows that the instrument is feasible for measurements of CH4 flux by the eddy correlation technique under field conditions. However, the present instrument suffers from several limitations. Most serious problem is the inadequate oscillation of He-Ne laser. In order to reduce the noise level of the instrument, further effort is required to control the oscillation of He-Ne laser.
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