Possible contribution of leakage currents from the Atlantic Ocean to the magnetic-field variations observed in Devon

Hart, A.M.; Krause, Pia; Rosser, W. G. V.

doi:10.1016/0031-9201(83)90132-2

Cited by 3 publications

(1 citation statement)

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“…The movement of ocean water through the geomagnetic field induces an electric current [ Kendall and Chapman , ; Hewson‐Browne , ], a phenomenon known as the ocean dynamo [ Rosser and Schlapp , ; Palshin et al ., ]. The ocean dynamo is known to generate telluric currents in the UK [ Chapman and Kendall , ; Osgood et al ., ; Brown and Woods , ; Hart et al ., ; Hart et al ., ]. The strength of the telluric contribution to measured SP depends on the length and orientation of the electrode dipoles [ Orihara et al ., ].…”

Section: Discussionmentioning

confidence: 99%

Tidal influence on self‐potential measurements

et al. 2016

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Long‐term surface and borehole self‐potential (SP) monitoring was conducted in the UK Chalk aquifer at two sites. The coastal site is ~1.7 km from the coast, and the inland site is ~80 km from the coast. At both sites, power spectral density analysis revealed that SP data contain the main ocean tidal periodic components. However, the principal lunar component (M2), the dominant ocean tidal component, was most significant at the coastal site. The M2 signal in surface‐referenced SP data at the inland site was partly due to telluric currents caused by the geomagnetic ocean dynamo. Earth and/or atmospheric tides also contributed, as the SP power spectrum was not typical of a telluric electric field. The M2 component in borehole‐referenced data at the inland site was below the significance level of the analysis method and was 2 orders of magnitude smaller than the M2 signal in borehole‐referenced SP data at the coastal site. The tidal response of the SP data in the coastal borehole is, therefore, primarily driven by ocean tides. These cause changes in fluid pressure and chemical concentration gradients within the coastal aquifer, leading to time varying electrokinetic and exclusion‐diffusion potentials. Borehole‐referenced SP measurements could be used to characterize and monitor tidal processes in coastal aquifers such as the intrusion of seawater.

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Section: Discussionmentioning

confidence: 99%

Tidal influence on self‐potential measurements

et al. 2016

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Electromagnetic induction studies

Chave¹,

Booker²

1987

Reviews of Geophysics

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This report constitutes an attempt to review the major developments and identify important trends in the broad field of geophysical electromagnetic induction and related phenomena over the past four years. Following in the spirit of previous reports of this type [e.g., Filloux, 1979; Hermance, 1983b;], the work of US researchers will be emphasized, although we will cover foreign research when appropriate. Many of the recent theoretical developments and the largest EM field program ever (EMSLAB) are the direct result of international cooperation, and strict adherence to the concept of national boundaries would result in an uninformative and incomplete review. Due to the fact that readers of this paper have diverse interests ranging from theory through field to laboratory studies, we have attempted to treat a variety of topics in EM induction and electrical geophysics. We begin by reviewing the state‐of‐the‐art in data collection, including new instrumentation. We continue by examining data analysis methods, with an emphasis on noise and bias reduction in the computation of the magnetotelluric and magnetic variations response functions. We then treat forward modelling developments, especially for two‐ and three‐dimensional induction problems. Recent progress has been made in EM induction inverse problems, and we assess the impact of this on the field. An overview of field measurements in North America is given, including the recent EMSLAB experiment which was carried out in 1985–1986 in the northwest US, southwest Canada, and contiguous offshore regions. This is followed by a review of developments in oceanic applications of EM principles.

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UK National Report for the Quadrennium 1979-1983 to the International Association of Geomagnetism and Aeronomy

1984

Geophysical Journal International

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Possible contribution of leakage currents from the Atlantic Ocean to the magnetic-field variations observed in Devon

Cited by 3 publications

References 7 publications

Tidal influence on self‐potential measurements

Tidal influence on self‐potential measurements

Electromagnetic induction studies

UK National Report for the Quadrennium 1979-1983 to the International Association of Geomagnetism and Aeronomy

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