Apparent Aeromagnetic Wavelengths of the Magnetic Signals of Ocean Swell

Lilley, F. E. M.; Weitemeyer, Karen

doi:10.1071/eg04137

Cited by 4 publications

(3 citation statements)

References 16 publications

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“…Lilley and Weitemeyer (2004a) calculated the apparent aeromagnetic wavelengths of the magnetic signals of the ocean swell. Lilley et al (2004b) also observed the magnetic fields generated by ocean waves near the sea surface. Semkin and Smagin (2012) investigated the effect of self-induction exhibited by the ocean wave-induced electromagnetic fields.…”

Section: Introductionmentioning

confidence: 92%

Impact of variable seawater conductivity on ocean wave-induced electromagnetic fields simulated with finite difference method

Ge¹,

Li²

2023

Front. Earth Sci.

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Electric fields generated by the motion of ocean waves through the Earth’s ambient geomagnetic fields and the induced secondary magnetic field can be observed at the seafloor and at the sea-surface, and even in the air. Most of current studies on ocean wave-induced electromagnetic fields assume that seawater conductivity is constant, and ocean waves are treated as regular waves with a fixed amplitude and frequency. However, these assumptions are inconsistent with actual ocean conditions. In this paper, we present a finite difference algorithm for simulating the ocean wave-induced electromagnetic fields with variable seawater conductivity. We investigate impacts of variable seawater conductivity on the electromagnetic fields induced by the wind waves and swell as well as mixed ocean waves, which are treated as the superposition of a number of regular waves with different frequencies and amplitudes, and analyze the characteristics of the induced electromagnetic fields.

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Section: Introductionmentioning

confidence: 92%

Impact of variable seawater conductivity on ocean wave-induced electromagnetic fields simulated with finite difference method

Ge¹,

Li²

2023

Front. Earth Sci.

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“…Ochadlick report aeromagnetic measurements in agreement with the theory of Weaver. Observations of the magnetic field disturbances of ocean waves were also reported by Fraser, Watermann and Lilley et al [6][7][8]. Garcia described a scheme for eliminating part or all of this surface wave-generated noise component based on reference data provided by signal proportional to the ocean surface [9].…”

Section: Introductionmentioning

confidence: 93%

Simulation of Ocean Wave-Generated Magnetic Field Disturbance Observed above Sea-Surface Based on Directional Spectrum

Xiong

Yang

Miao

2013

AMR

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Ocean wave have a magnetic field disturbance, caused by the motional induction of sea water moving in the steady main field of Earth. Mass experiment indicates ocean wave-generated magnetic field disturbance can be a major limitation on the performance of airborne magnetic anomaly detection. To check the character of such disturbance observed above sea-surface, a harmonic ocean wave-generated magnetic field disturbance mathematical model based on Weavers monochromatic wave-generated magnetic field model and ocean wave directional spectrum is proposed. Algorithm is presented for real-time simulation of ocean wave-generated magnetic field disturbance corresponding to the proposed mathematical model. Numerical simulations of ocean wave-generated magnetic field disturbance are sampled above sea-surface by a stationary magnetometer and an airborne magnetometer moving steadily along a rectilinear path. Spectrum analysis of the samples is performed. Simulations results indicate that the proposed harmonic ocean wave magnetic field disturbance mathematical model can well-simulate the real sea conditions. Numerical simulations also reveal that there is a Doppler frequency shift with the increase of magnetometer flight speed. Moreover, energy of the magnetic field disturbance is more dispersed and frequency band is wider with the increase of magnetometer flight speed.

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“…Magnetometry has emerged as a promising alternative to traditional velocimetry techniques (Tyler, 2006; Tyler et al., 1997) to quantify large‐scale marine flows, including vessel wakes (Zou & Nehorai, 1998), tsunami detection and parameterization (Lin et al., 2021; Minami et al., 2021; Zhang et al., 2014), wave measurements (Davis, 1991; Podney, 1975), and ocean current profiling (Filloux, 1973; Lilley & Weitemeyer, 2004; Longuet‐Higgins et al., 1954). Instead of measuring the velocity field directly, these magnetic techniques measure the flow‐induced magnetic fields that naturally arise when electrically conductive fluids, such as seawater, move through a magnetic field, such as the Earth's geomagnetic field (Faraday, 1832; Podney, 1975; Tyler et al., 1997, 2003).…”

Section: Introductionmentioning

confidence: 99%

Magnetic Signature of Vertically Migrating Aggregations in the Ocean

Dabiri

2023

Geophysical Research Letters

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Biologically generated mixing from vertically migrating aggregations of plankton remains a poorly understood mechanism by which heat and solutes are potentially mixed in the ocean (Dabiri, 2009;Dewar et al., 2006;Houghton et al., 2018;Wilhelmus & Dabiri, 2014). While the induced flow and stirring associated with an isolated animal occur at the scale of the swimmer (Visser, 2007), plankton often exist in dense swarms over 10s of meters in height and 100s of meters in width (Huntley & Zhou, 2004;Sato et al., 2013), and collectively traverse 100s of meters during their diel vertical migrations (Sato et al., 2013;Wiebe et al., 1979). The emergence of aggregation-scale mixing eddies comparable to the stratification length scales of the water column has been proposed as a potential mechanism through which vertically migrating aggregations can induce appreciable transport in the water column through which the organisms migrate (

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Apparent Aeromagnetic Wavelengths of the Magnetic Signals of Ocean Swell

Cited by 4 publications

References 16 publications

Impact of variable seawater conductivity on ocean wave-induced electromagnetic fields simulated with finite difference method

Impact of variable seawater conductivity on ocean wave-induced electromagnetic fields simulated with finite difference method

Simulation of Ocean Wave-Generated Magnetic Field Disturbance Observed above Sea-Surface Based on Directional Spectrum

Magnetic Signature of Vertically Migrating Aggregations in the Ocean

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