Monitoring and Analysis of the Marine Underwater Electric Field of the Typical Shallow Sea Area
The marine underwater electric field can be divided into two types according to the difference of the generation mechanism: natural field and man-made field.The natural field is generated by the motion currents of the ionosphere and the magnetic layer,the thunderstorm around the world and the seawater motion in the geomagnetic field.The man-made field arises from the industrial facility along the coast,such as large power stations,transformer stations and electric transmission lines.Monitoring and analysis of the marine underwater electric field have been widely paid attention by the marine electromagnetism,marine geology and geophysics exploration and marine disaster prediction.In this study,the monitoring system consisted of a three-axis electric field sensor is integrated and constructed.This system includes three ingredients: the underwater body,the optical fiber/electric power composite cable and the control station.The working performance of the system is tested by use of the controlled electric dipole source after the system is deployed in the sea.The test results show that the system is working with sufficient accuracy and the measured data is credible.The underwater electric field has been measured during one year period by the system in the shallow water of the northern yellow sea where the sea water depth is about 35m.The measurement covers frequency from DC up to 1000Hz.It is found that the approximate linear frequency modulation appears periodically in the underwater electromagnetic field signal in some time.It may be generated by the leakage current of the industrial electric equipment as a result of the phase difference of the different power lines.The low frequency signal (DC-1Hz) of the underwater electric field is related with the sea conditions and the FFT spectral shows that the signal energy at the high sea condition is greater than that at the low sea condition in the frequency range below 0.1Hz.The polarization of horizontal component of low frequency signal is linear.The direction of polarization is approximately perpendicular to the direction of the sea water motion.The polarization of the power electric fields horizontal component (50Hz) is elliptical.The underwater electric field generated by the thunder and lighting is short pulsation signal which has a frequency range from 1Hz up to 1000Hz.The three-component amplitudes of the electric field signature are 360V/m,400V/m and 198V/m respectively.The spectrum peak is broad,and the center frequency is 1.5Hz,5.8Hz and 22.8Hz respectively.The theoretical analysis of the previous characteristics is presented in this paper.
marine underwater electric field monitoring analysis
Lü Junjun Yue Ruiyong Yu Feng
Science and Technology on Underwater Test and Control Laboratory, Dalian, PRC Dalian Scientific Test and Control Technology Institute, Dalian, PRC
国际会议
长沙
英文
35-40
2012-06-15（万方平台首次上网日期，不代表论文的发表时间）