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The effects of localized source currents on Earth's magnetotelluric (MT) responses have been reported in the literature in terms of the changes in period and subsurface structure. The focus in this study is on the bias within the MT…

Geophysics · Physics 2020-06-08 Shinya Sato

The magnetotelluric (MT) responses of the Earth are biased by spatially heterogeneous source fields. Recently, such biases have been reported even in mid-latitude areas, where localized source currents rarely flow. This study focuses on…

Geophysics · Physics 2020-12-07 Shinya Sato

Current source models for the Earth's main geomagnetic field are calculated employing conventional discrete inverse theory methods. Source structures are spherical surfaces placed at the surface of the Earth's core, and at the surface of…

Geophysics · Physics 2013-12-18 Terence V. Sewards

The time-varying geomagnetic field is a superposition of contributions from multiple internal and external current systems. A major source of geomagnetic variations at periods less than a few years are current systems external to the solid…

Space Physics · Physics 2025-03-11 Jingtao Min , Alexander Grayver

Evidence of fast variations in the Earth's core field are seen both in magnetic observatory and satellite records. We present here how they have been identified at the Earth's surface from ground-based observatory records and how their…

Geophysics · Physics 2022-01-17 V. Lesur , N. Gillet , M. D. Hammer , M. Mandea

The inverse problem which consists of determining the flow at the Earth's Core Mantle Boundary according to an outer core magnetic field and secular variation model, has been investigated through a Bayesian formalism. To circumvent the…

Geophysics · Physics 2015-06-17 Julien Baerenzung , Matthias Holschneider , Vincent Lesur

We characterize the response of the quiet time (no substorms or storms) large-scale ionospheric transient equivalent currents to north-south and south-north IMF turnings by using a dynamical network of ground-based magnetometers. Canonical…

Space Physics · Physics 2017-05-17 J. Dods , S. C. Chapman , J. W. Gjerloev

For the past few centuries, the temporal variation in the Earth's magnetic field in the Pacific region has been anomalously low. The reason for this is tied to large scale flows in the liquid outer core near the core-mantle boundary, which…

Geophysics · Physics 2022-01-05 Mathieu Dumberry , Colin More

[..] The change in the magnetic configuration due to the increase/decrease of electric current for different force-free models (potential, linear and nonlinear force-free fields) has never been studied in detail before. Here we focus…

Solar and Stellar Astrophysics · Physics 2015-05-28 S. Regnier

Composed of shocked solar wind, the Earth's magnetosheath serves as a natural laboratory to study the transition of turbulence from low Alfv{\'e}n Mach number, $M_\mathrm{A}$, to high $M_\mathrm{A}$. The simultaneous observations of…

Space Physics · Physics 2020-08-05 Hui Li , Wence Jiang , Chi Wang , Daniel Verscharen , Chen Zeng , C. T. Russell , B. Giles , J. L. Burch

The location of the terrestrial magnetopause (MP) and it's subsolar stand-off distance depends not only on the solar wind dynamic pressure and the interplanetary magnetic field (IMF), both of which play a crucial role in determining it's…

Space Physics · Physics 2017-09-06 Madhusudan Ingale , P. Janardhan , K. Fujiki , Susanta Kumar Bisoi , Diptiranjan Rout

Stably stratified layers are present in stellar interiors (radiative zones) as well as planetary interiors - recent observations and theoretical studies of the Earth's magnetic field seem to indicate the presence of a thin, stably…

Solar and Stellar Astrophysics · Physics 2019-10-10 J. Philidet , C. Gissinger , F. Lignières , L. Petitdemange

Periodic variations in the Sun and Moon's gravitational pull cause small changes in Earth's rotational axis direction called nutation. Nutation components in the retrograde quasi-diurnal frequency band measured in the terrestrial reference…

Earth and Planetary Astrophysics · Physics 2025-07-14 J. Rekier , S. A. Triana , A. Barik , D. Abdulah , W. Kang

We present a new model of time-dependent flow at low latitudes in the Earth's core between 2000 and 2018, derived from magnetic field measurements made on board the {\it Swarm} and CHAMP satellites and at ground magnetic observatories. The…

Geophysics · Physics 2019-11-11 Clemens Kloss , Christopher Finlay

Time-distance helioseismic measurements in surface- and deep-focus geometries for wave-paths that distinguish surface magnetic contributions from those due to deeper perturbations beneath a large sunspot are presented and analysed. Travel…

Astrophysics · Physics 2008-02-21 S. P. Rajaguru

Seismic and geodynamic studies indicate that the boundary between the Earth's liquid outer core and solid mantle is not spherical, but is likely characterized by topography in the form of inverted mountains and valleys that have typical…

Geophysics · Physics 2025-06-10 Tobias G. Oliver , Eric G. Blackman , John A. Tarduno , Michael A. Calkins

We report a calculation of time-dependent quasi-geostrophic core flows for 1940-2010. Inverting recursively for an ensemble of solutions, we evaluate the main source of uncertainties, namely the model errors arising from interactions…

Geophysics · Physics 2016-03-01 N Gillet , D Jault , C. C. Finlay

Surface waves on Earth's magnetopause have a controlling effect upon global magnetospheric dynamics. Since spacecraft provide sparse in situ observation points, remote sensing these modes using ground-based instruments in the polar regions…

We provide a space domain oriented separation of magnetic fields into parts generated by sources in the exterior and sources in the interior of a given sphere. The separation itself is well-known in geomagnetic modeling, usually in terms of…

Numerical Analysis · Mathematics 2015-06-04 Christian Gerhards

Estimating high resolution models of the Earth's core magnetic field and its time variation in the polar regions requires that one can adequately account for magnetic signals produced by polar ionospheric currents, which vary on a wide…

Space Physics · Physics 2023-09-11 Clemens Kloss , Christopher C. Finlay , Karl M. Laundal , Nils Olsen
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