Study on the regional distribution of tropospheric methane using a rapidly and continuously measuring instrument

利用快速连续测量仪研究对流层甲烷区域分布

基本信息

批准号：
02402014
负责人：
OGAWA Toshihiro
金额：
$ 7.68万
依托单位：
University of Tokyo
依托单位国家：
日本
项目类别：
Grant-in-Aid for General Scientific Research (A)
财政年份：
1990
资助国家：
日本
起止时间：
1990 至 1991
项目状态：
已结题

来源：
https://kaken.nii.ac.jp/grant/KAKENHI-PROJECT-02402014/
关键词：
greenhouse effect methane regional distribution emission sourse

项目摘要

In 1990 modifying the methane instrument that we had developed, we designed and fabricated a new model to be adapted to a moving platform and made laboratory tests on its performance. A field test observation was made on the research vessel Shirase cruising from Tokyo to the Antarctica with respect to its performance aboard a vibrating and moving platform and the disturbance of atmospheric water vapor to the measurement. The observation exhibited a precision of about 5% with a measurement time constant of a few minutes when a statistical data processing was applied to remove periodic oscillations in the data due to the vessel engine. The processed data depicted the latitudinal distribution of tropospheric methane. In 1991 we made several performance tests of the instrument, to find that it was the stability of the laser that was limiting measurement precision. The temperature fluctuation was thought to be a major source to degrade the stability. We improved the instrument to keep tempe … More rature constant and spatially uniform around the laser oscillator tube.After the end of the projected research period, in 1992 and 1993 we made further improvement of the instrument. A significant improvement was attained by adding a feedback roop to stabilize the laser output, in which the distance between the laser resonator mirrors was adjusted with a piezoelectric element. The improved instrument exhibited a precision of 1% with a measurement time constant of a few minutes, and was used in the observations on board an automobile and an airship with respect to the spatial distributions of atmospheric methane concentration over and around rice paddies in Ibaraki-ken and over the Tokyo metropolitan area. Applying a diffusive transport model to the methane concentration distributions observed around rice paddies, we were able to estimate the emission source strength of methane from rice paddies. The estimated value exhibited a reasonable agreement with those deduced from the chamber method and the gradient method, implying a possibility of estimating the methane emission flux in a horizontal scale of a few 100 m to a few km with the aid of the diffusive transport model. The airship observation over the Tokyo metropolitan area revealed an area of large methane mixing ratio exceeding 2 ppmv around Urayasu, suggesting a strong emission source of methane. Less

1990年，我们修改了我们开发的甲烷仪器，我们设计并制造了一种新模型，以适应移动平台，并对其性能进行了实验室测试。关于其在振动和移动的平台上的性能以及大气水蒸气的灾难以进行测量，对从东京到南极的研究船Shirase进行了现场测试观察。当应用统计数据处理以消除由于血管发动机而导致数据的周期性振荡时，该观察结果的精度约为5％，测量时间常数为几分钟。描述了处理后的数据对流层甲烷的纬度分布。在1991年，我们对该仪器进行了几次性能测试，以发现激光的稳定性限制了测量精度。温度波动被认为是降解稳定性的主要来源。我们改善了保持节奏的仪器……在激光振荡器管周围更加恒定和空间均匀。通过添加反馈Roop来稳定激光输出，可以通过重大改进进行重大改进，在该输出中，激光谐振器镜之间的距离用压电元件调节。改进的仪器的精度为1％，测量时间常数为几分钟，并用于船上的汽车和飞艇，相对于在伊巴拉基 - 凯恩（Ibaraki-ken）和东京大都市区域的稻田上和周围的大气甲烷浓度的空间分布。在稻田周围观察到的甲烷浓度分布中，应用不同的传输模型，我们能够估计稻田中甲烷的发射源强度。估计值与室法和梯度方法得出的估计值表现出合理的一致性，这意味着有可能借助分化的传输模型估算甲烷发射通量的水平尺度为几100 m至几公里。东京都会区的飞艇观察结果表明，大型甲烷混合率的面积超过urayasu周围2 ppmv，这表明甲烷的发射源很强。较少的