Geomagnetic induction on a transatlantic communications cable

Medford, L. V.; Meloni, A.; Lanzerotti, L. J.; Gregori, G. P.

doi:10.1038/290392a0

Cited by 22 publications

(22 citation statements)

References 10 publications

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“…For a submarine cable, (1) is integrated laterally along the cable length, and hence the voltage very nearly reflects the total amount of transport across the cable. Motionally induced fields on cables have been detected in many experiments [e.g., Longuet-Higgins, 1949;Stommel, 1954;Cox et al, 1964;Teramoto, 1971;Duffus and Fowler, 1974;Richards, 1977;Medford et al, 1981;Mori, 1987;Kawatate et al, 1991;Chave et al, 1992b;Teramoto and Kojima, 1994]. Until the 1970s, comparisons of these measurements with theory were not entirely successful because the studies focused on tidal components where (1) is not satisfied because self-and mutual-induction effects are significant.…”

Section: Theorymentioning

confidence: 99%

Motional induction effect on the planetary‐scale geoelectric potential in the eastern North Pacific

Fujii¹,

Chave²

1999

J. Geophys. Res.

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Section: Theorymentioning

confidence: 99%

Motional induction effect on the planetary‐scale geoelectric potential in the eastern North Pacific

Fujii¹,

Chave²

1999

J. Geophys. Res.

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“…As with any time series, the ability to differentiate a true dc This paper presents a short review of the present status of potential from low-frequency components is limited by the telluric potential measurements using planetary-scale, unpowered telecommunications cables with the emphasis on the very low frequency limit. The discussion explicitly does not include higher frequency observations which have been applied to studies of ionospheric and magnetospheric processes [e.g., Medford et al, 1982Medford et al, , 1989Lanzerotti et al, 1992a] and magnetotelluric investigations of deep earth conductivity structure [e.g., Richards, 1980;Egbert and Booker, 1992 Table 1). In addition to the long cable observations, there are several reports of year-long (or more) measurements of telluric electric fields using the autonomous short span sensors described in Filloux [1987].…”

Section: Measurements Of the Time-average Or DC Potential Have Been Mmentioning

confidence: 99%

Large‐scale electric field measurements on the Earth's surface: A review

Lanzerotti¹,

Chave²,

Sayres³

et al. 1993

J. Geophys. Res.

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There exist only a few reported measurements of quasi‐stationary (near dc) electric potentials over very large spatial scales (hundreds of kilometers or more) on the Earth's surface. Such measurements have typically been made using unpowered submarine telecommunications cables. The measurements pose unique experimental challenges and require careful procedures to avoid data contamination by electrode contact potentials and local ground currents. In addition, there are possible interpretational problems from pervasive, poorly understood, low‐frequency electric fields induced by ocean water motion through the Earth's stationary magnetic field. Nevertheless, estimates of the magnitude of the electric field computed from large‐scale potential difference measurements, made principally to date in the Pacific Ocean, can be used to place a limit on the size of the toroidal magnetic field at the core‐mantle boundary under certain conditions on the Earth's electrical conductivity profile. Thus, large‐scale electric potential measurements can serve as an adjunct probe of the Earth's dynamo process in addition to measurements of the poloidal magnetic field and its secular changes made at and above the surface of the Earth. A review of all of these data suggests that the toroidal and poloidal magnetic fields at the top of the core are comparable in magnitude.

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“…[1983]. Results in magnetospheric/ionospheric, oceanic, and solid Earth studies are included in several publications over the last decade [e.g., Medford et al, 1982;Lanzerotti et al, , 1993Thomson et al, 1986; Chave et al, 1992; and references therein]. This paper describes some initial results obtained from simultaneous measurements of the geoelectric potential over large (1000's of km) distances using two separate Pacific cables.…”

Section: Introductionmentioning

confidence: 99%

Geoelectric power spectra over oceanic distances

Fujii

Lanzerotti

Utada

et al. 1995

Geophysical Research Letters

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We present initial results of simultaneous measurements of the geoelectric potential as measured across two long cable routes in the Pacific (Guam to Philippines and California to Hawaii) separated by ∼6h in local time and ∼30° in latitude. Over the frequency range ∼10−5 to 1.67 × 10−3Hz the power levels tend to be enhanced near local noon along the two routes, especially during geomagnetic quiet intervals. During the seven days analyzed, geoelectric power levels up to 104 (mV/km)²/km were measured on a geomagnetically disturbed day. The power levels at the longest periods, ∼17m to ∼150m, are generally found to be largest along the route at lower geomagnetic latitudes (Guam to Philippines) when comparisons are made at equivalent local times. In contrast, the power levels for periods in the hydromagnetic wave region (periods ≲5m) tend to be larger at all local times for the higher geomagnetic latitude route. The nightside geoelectric power levels along the higher latitude route tend to increase with increasing geomagnetic activity.

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Geomagnetic induction on a transatlantic communications cable

Cited by 22 publications

References 10 publications

Motional induction effect on the planetary‐scale geoelectric potential in the eastern North Pacific

Motional induction effect on the planetary‐scale geoelectric potential in the eastern North Pacific

Large‐scale electric field measurements on the Earth's surface: A review

Geoelectric power spectra over oceanic distances

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