Energy Evolution of the Ocean Wave Spectrum and Distribution of the Induced magnetic Field Intensity
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摘要: 海洋电磁探测技术性能明显受海洋电磁环境噪声影响, 而在地磁场里, 由海浪运动产生的感应磁场是这个环境中的核心噪声源之一, 为更深入的探究海浪感应磁场的形成机理、分布特性及其分布规律, 文中采用Pierson-Moskowit海浪谱结合Weaver电磁理论体系, 采用蒙特卡洛随机抽样方法仿真二维海面在不同风速下的动态特征, 采用麦克斯韦方程组实现海浪感应磁场的公式化表达, 模拟不同风速场景下感应磁场的三维空间分布及频谱特性。仿真结果表明: 当风速持续上升, 波浪从低幅未发育阶段持续过渡到复杂成熟的充分发展状态; 风速的持续上升, 磁感应强度与海浪呈正相关增强; 感应磁场在频谱上显示窄带集中特性, 伴随风速的持续增长, 优势频率往低频域漂移, 主频附近出现能量汇聚现象, 在低于主频的低频段, 磁场强度随频率升高近似线性增长; 而在高于主频的高频段, 其强度则随频率升高呈指数衰减趋势。研究结果可为海洋电磁探测领域的噪声建模与信号提取给予理论及仿真参考。
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关键词:
- 海洋电磁探测 /
- Pierson-Moskowitz海浪谱 /
- 频谱特性 /
- 磁场强度 /
- 感应磁场
Abstract: The performance of marine electromagnetic detection is significantly affected by the ambient electromagnetic noise in the ocean, among which the magnetic field induced by ocean waves moving through the Earth's magnetic field constitutes a core noise source. To further investigate the formation mechanism, distribution characteristics, and patterns of this wave-induced magnetic field, this study employs the Pierson-Moskowitz wave spectrum combined with the Weaver's electromagnetic theory framework. The dynamic characteristics of a two-dimensional sea surface under varying wind speeds were simulated using the Monte Carlo random sampling method, and the wave-induced magnetic field was formulated analytically via Maxwell's equations. The research focus was to simulate the three-dimensional spatial distribution and spectral properties of the induced magnetic field under different wind scenarios. Simulation results indicate that as wind speed increases, wave evolution progresses from a low-amplitude, underdeveloped state to a complex and fully developed condition. Concurrently, the magnetic induction intensity exhibits a positive correlation with wave activity. Spectrally, the induced magnetic field demonstrates a narrowband concentration characteristic. With increasing wind speed, the dominant frequency shifts towards the lower frequency domain, accompanied by energy aggregation near the primary frequency. In the frequency band below the dominant frequency, the magnetic field intensity increases approximately linearly with frequency, while in the band above the dominant frequency, it decays exponentially with increasing frequency. The findings of this study provide theoretical and simulation support for noise modeling and signal extraction in the field of marine electromagnetic detection. -
图 2 风速5 m/s P-M三维波形图
Figure 2. Three-dimensional waveform of P-M spectrum at wind speed is 5 m/s
图 3 风速10 m/s P-M三维波形图
Figure 3. Three-dimensional waveform of P-M spectrum at wind speed is 10 m/s
图 4 风速15 m/s P-M三维波形图
Figure 4. Three-dimensional waveform of P-M spectrum at wind speed is 15 m/s
图 7 不同风速下磁场的频谱特性曲线
Figure 7. Spectral characteristics of magnetic field under different wind speeds
图 9 不同风速下磁场随深度的变化
Figure 9. Variation of magnetic field with depth at different wind speeds
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