Method of measurement Methane hydrate using Acoustic Doppler Current Profiler

近年来，由于石油、煤炭等有限资源的枯竭，甲烷水合物备受关注。与石油和煤炭相比，MH产生的二氧化碳和氮氧化物很少。MH的这种行为意味着MH在空气污染和地球变暖等环境问题上远远优于石油和煤炭。另一方面，MH的发展也非常担心MH的发展破坏海底生态系统。我们还应该提前评估开发对生态系统的影响和风险。因此，测量MH和/或甲烷烟羽的喷发是非常重要的。针对目前深海MH测量研究较少的问题，提出了一种利用声学多普勒海流剖面仪(ADCP)测量MH深度剖面的方法。在该测量方法中，将超声波的传播视为反问题，利用超声波在水下传播的模型来测量MH的深度分布。由于ADCP可以获得三维速度，因此该方法适用于深海MH动力学的监测。

Recently, Methane Hydrate(MH) has attracted much attention because of depletion of a finite resource such as oil and coal. The generation of carbon dioxide and the oxide of nitrogen by MH are very little compared with oil and coal. This behavior of MH means that the MH is extremely superior to oil and coal in terms of environmental problem such as air pollution and earth warming.On the other hand, there is also great fear that the development of MH damages the benthic ecosystem. We should also assess the influence and risk of ecosystem by the development in advance. From these reasons, it is very important to measure the blowout of MH and/or methane plume. However, very few studies have been reported on measurement of MH in deep-sea area.In this study, the author proposed a new measurement method of MH depth profiles with Acoustic Doppler Current Profilers(ADCP). In this measurement method, the propagation of ultrasonic waves was regarded as inverse problem, and the depth profile of MH can be measured by model of propagation of ultrasonic underwater. Since ADCP can be obtained the three-dimensional velocity, the present method is suitable for monitoring in order to understand MH dynamics under deep sea.