Research On Magnetic Effect By Waves At Limited Depth Of The Ocean

Varieties of large scale ocean water movement, such as surface waves, internalwaves, tides and ocean currents, etc., can induce the corresponding electromagneticfield in the Earth Magnetic field. Study of the induced electromagnetic field which beinduced by scale movement of ocean water, and explore methods of measuring them,then through the electromagnetic measurement to understand varieties of ocean watermovement, it is an important aspect in marine electromagnetic studies.The electromagnetic noise interference of human activities to marine magneticmeasurements is small, but the electromagnetic noise of the marine environment isrelatively large. This paper mainly studies ocean water movement of the ocean waves,in the actual ocean magnetic measurements, would include the impact of the oceanwaves, when the electromagnetic fields noises are close to the detected target signalsmagnitude and band, these are non-negligible noise interference. Weaver has beenproposed for this problem the mathematical theory of electromagnetic ocean wave’smodel, and has derived the analytical form of electromagnetic of ocean waves, but thestudy only when the water is infinitely deep case. Weaver model under the coastalcontinental shelf has no applicability. The marine coastal shelf area is the developmentof human activity areas, the magnetic field measurements in the water reservoir relatedto the mineral exploration and mining, water pipe cable maintenance, aquatic fisheries,navigation, anti-submarine and other important areas of national economy and nationalsecurity, thus for finite depth waters, excluding magnetic waves interfere with accuratemeasurement is important.This paper analyzes the theory of Weaver, revised Weaver model, establish amathematical model of ocean waves electromagnetic induction at limited deep-water,the limited deep waters, especially oceans on the continental shelf, the inducedmagnetic field of wave movement is solved, has been sensitive to magnetic field andwave height, ocean depth and other parameters. The underwater robot as a carrier, withthe optically pumped cesium magnetometer in the Songhua Lake water and carried outmagnetic field measurements experiments, study of magnetic fluctuation of themeasured data caused by waves, analyze measured data that the ship drag optically pumped cesium magnetometer, a detailed analysis have done with magneticmeasurement data during the other vessel pass through, the ship will leave a waveamplitude of about0.5m, make condition to validate theoretical models. Although theSonghua Lake is a freshwater lake, but there are certain salinity and conductivity,based on our established model of modified Weaver and local hydrological conditionson the lake, analyze calculation of the magnetic field, and the fluctuation of themeasured magnetic data were compared, there is good the degree of matching. Thesestudies have a positive significance to measure the magnetic field, provideinterpretation of fluctuations in the marine magnetic survey data, inversion, reduce themagnetic measurement noise, and improve the measurement accuracy.