HR: 0800h
AN: A21D-0905    [Abstracts]
TI: Application of Improved Tin-dioxide Detector for In-situ Airborne Measurements of Atmospheric Methane Concentration as the Validation Experiment of GOSAT
AU: * SUTO, H
EM: suto.hiroshi@nies.go.jp
AF: Center for Global Environmental Research, National Institute for Environmental Studies, 16-2 Onogawa, Tsukuba, Ibaraki, 305-8506 Japan
AU: OGUMA, H
EM: oguma@nies.go.jp
AF: Center for Global Environmental Research, National Institute for Environmental Studies, 16-2 Onogawa, Tsukuba, Ibaraki, 305-8506 Japan
AU: INOUE, G
EM: inouegen@nies.go.jp
AF: Center for Global Environmental Research, National Institute for Environmental Studies, 16-2 Onogawa, Tsukuba, Ibaraki, 305-8506 Japan
AB: The concentration retrieved from the spectroscopic data of satellite must be validated by other observations. There are two types; an in-situ vertical profile observation and the ground base FTS observation. The latter observation is in high resolution and in good SN ratio without disturbances such as surface reflection spectra, cloud and aerosol path-radiance problems, but the common error in the retrieval algorithm is inevitable. The former is quite reliable and the vertical profile observation is very useful to validate the retrieval calculation, but the frequency of observation is limited by the cost of aircraft operation. Both methods are applied in GOSAT project. In order to measure the vertical profile of atmospheric methane concentration, the safe and low power consumption measurement system is required fitting to aircraft observations. The methane sensor based on a tin-dioxide detector fits to these requirements but the response time to the concentration change is rather long. In this paper, the improvement of response time is reported. One of the factors to determine the response time is the time required for the methane to penetrate through the overcoat Pt and Pd layer and reach to SnO₂ layer, and a new sensor with thin overcoat layer was developed. The fast air-flow keeps the fresh air on detector surface, and the high temperature of detector enhances the diffusion speed in solid. The optimal airflow rate and the optimal heating voltage for detector were investigated in the range from 20sccm to 150sccm and in the range from 3.3V to 3.8V, respectively. The response time of this detector was examined by changing the methane concentration between 1700 ppb and 2000ppb, and the 90 percent response time was found to be 16 seconds. The measurement system is very compact and light in weight (20 kg) and the power consumption is 15W. The vertical profile of atmospheric methane concentration in the altitude from 0 to 3000m has been measured. The measured methane concentration has good correlation with the concentration of carbon dioxide, potential temperature, and specific humidity measured simultaneously. The planetary boundary layer heights determined by the vertical profiles of them agreed well each other. This improved system can provide the reliable validation data for GOSAT project.
DE: 0394 Instruments and techniques
DE: 0428 Carbon cycling (4806)
DE: 0452 Instruments and techniques
DE: 3394 Instruments and techniques
SC: Atmospheric Sciences [A]
MN: Fall Meeting 2005