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An Experimental study of the Earth's Electric Field

地球电场的实验研究

基本信息

批准号：
14204041
负责人：
UTADA Hisasi
金额：
$ 31.03万
依托单位：
The University of Tokyo
依托单位国家：
日本
项目类别：
Grant-in-Aid for Scientific Research (A)
财政年份：
2002
资助国家：
日本
起止时间：
2002 至 2004
项目状态：
已结题

来源：
https://kaken.nii.ac.jp/grant/KAKENHI-PROJECT-14204041/
关键词：
Earth's electric field Geomagnetic filed Submarine cable Outer core Geodynamo System development Ocean flux Electrical conductivity

项目摘要

This three-year research project aimed to develop a new observation system that enables us to record time variations of the electric field of the Earth at deep ocean bottom by using a long (10-100 km) cable.. The research result of our feasibility study concluded that the use of such a system is essential to detect the electric field of Toroidal magnetic mode in the outer core. The geophysical importance of the observation of this physical quantity is obvious because it is expected to give significant constraints on the magneto-hydrodynamics in the outer core,. Besides this signal from the outer core, the proposed observation system is considered to be useful for studying long-term variabilities of ocean flux and the electrical conductivity structure in the deep mantle.The system consists of the main recording unit and a 10 km long cable. It is designed to be installed by using a deep-tow system and to be recovered by using a ROV (Remotely Operating Vehicle). The system was designed by … More assuming DT-4000 and Kaiko-10K both of JAMSTEC for a deep-tow and ROV. During the first year, an instrument was built and on-land tests were performed. In the second year, we tried to install the system in the Philippine Sea (near Minami-Daito Island), but the installation was failed due to a break of the cable soon after the beginning of run. Causes for this failure were extensively examined and clarified. Several modifications were made to the system design and the improved system was built at the end of the second year of this project. This system was named EFOS-10 that stands for Earth's electric Field Observation System with a 10 km long cable. The EFOS-10 installation was successfully made by using DT-4000 on R/V Natsushima cruise in May, 2004. Its recovery was scheduled one year after the installation, i.e., in May, 2005. It is because of the availability of ROV of JAMSTEC (The vehicle of Kaiko-10K was lost in 2003, and its supplementary vehicle Kaiko-7K became available in May 2005).The recording unit was successfully recovered, form which 1-year-long time series record of electric variations was obtained. The data quality was examined and was confirmed to be satisfactory as it has been expected. It is concluded that the EFOS-10 can be useful for various electromagnetic investigations at sea. Less

这个为期三年的研究项目旨在开发一种新的观测系统，使我们能够使用长（10-100公里）电缆记录海底深处地球电场的时间变化。我们的可行性研究结果表明，使用这样的系统来检测外核环向磁模的电场是必不可少的。这一物理量的观测在地球物理上的重要性是显而易见的，因为它有望对外核的磁流体动力学给出重要的约束。除了外核信号外，该观测系统还可用于研究海洋通量的长期变化和深部地幔的电导率结构。该系统由主记录单元和一条10公里长的电缆组成。它被设计为使用深拖曳系统安装，并使用ROV（远程操作车辆）进行回收。该系统由…More公司设计，假设JAMSTEC公司的DT-4000和Kaiko-10K都适用于深水拖带和ROV。在第一年，制造了一台仪器，并进行了陆地测试。第二年，我们尝试在菲律宾海（靠近Minami-Daito岛）安装该系统，但在开始运行后不久，由于电缆断裂，安装失败。对失败的原因进行了广泛的检查和澄清。对系统设计进行了几次修改，改进后的系统在本项目第二年年底建成。该系统被命名为EFOS-10，代表地球电场观测系统，拥有10公里长的电缆。2004年5月，EFOS-10安装在R/V Natsushima巡航上成功使用DT-4000。它的恢复计划在安装一年后，即2005年5月。这是因为JAMSTEC的ROV的可用性（Kaiko-10K车辆在2003年丢失，它的补充车辆Kaiko-7K在2005年5月可用）。成功回收了记录单元，获得了1年的电变化时间序列记录。对数据质量进行了检查，并证实如预期的那样令人满意。结果表明，EFOS-10可用于各种海上电磁探测。少