Parent magnetic field models for the IGRF-12GFZ-candidates

Lesur, Vincent; Rother, M.; Wardinski, Ingo; Schachtschneider, Reyko; Hamoudi, Mohamed; Chambodut, Aude

doi:10.1186/s40623-015-0239-6

Cited by 39 publications

(29 citation statements)

References 15 publications

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“…The external field parametrization closely follows that of the IGRF-12 candidate by Lesur et al (2015) in which Est and IMF By control the rapidly varying part of the field. In the version we use, this is done by the SVMD index, a satellite-based modification (Kunagu et al 2013) of the VMD index (Thomson & Lesur 2007).…”

Section: Large-scale External Field Modelmentioning

confidence: 99%

An annual proxy for the geomagnetic signal of magnetospheric currents on Earth based on observatory data from 1900–2010

Pick

Korte

2017

Geophysical Journal International

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S U M M A R YWe introduce the Annual Magnetospheric Currents index as long-term proxy for the geomagnetic signal of magnetospheric currents on Earth valid within the time span 1900-2010. Similar to the widely used disturbance storm time and 'Ring Current' indices, it is based on geomagnetic observatory data, but provides a realistic absolute level and uncertainty estimates. Crucial aspects to this end are the revision of observatory crustal biases as well as the implementation of a Bayesian inversion accounting for uncertainties in the main field estimate, both required for the index derivation. The observatory choice is based on a minimization of index variance during a reference period spanning 1960-2010. The new index is capable of correcting observatory time series from large-scale external signals in a user-friendly manner. At present the index is only available as annual mean values. An extension to hourly values for the same time span is in progress.

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Section: Large-scale External Field Modelmentioning

confidence: 99%

An annual proxy for the geomagnetic signal of magnetospheric currents on Earth based on observatory data from 1900–2010

Pick

Korte

2017

Geophysical Journal International

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“…However, a procedure for correcting the magnetic field data for the "VFM-ASM disturbance field" has been found in the meantime (c.f. Lesur et al 2015), as discussed in detail by Tøffner-Clausen et al (2016), which allows us to now also include vector gradient data in our new model.…”

Section: Introductionmentioning

confidence: 99%

A model of Earth’s magnetic field derived from 2 years of Swarm satellite constellation data

et al. 2016

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More than 2 years of magnetic field data taken by the three-satellite constellation mission Swarm are used to derive a model of Earth's magnetic field and its time variation. This model is called SIFMplus. In addition to the magnetic field observations provided by each of the three Swarm satellites, explicit advantage is taken of the constellation aspect of Swarm by including East-West magnetic intensity and vector field gradient information from the lower satellite pair. Along-track differences of the magnetic intensity as well as of the vector components provide further information concerning the North-South gradient. The SIFMplus model provides a description of the static lithospheric field that is very similar to models determined from CHAMP data, up to at least spherical harmonic degree n = 75. Also the core field part of SIFMplus, with a quadratic time dependence for n ≤ 6 and a linear time dependence for n = 7-15, demonstrates the possibility to determine high-quality field models from only 2 years of Swarm data, thanks to the unique constellation aspect of Swarm. To account for the magnetic signature caused by ionospheric electric currents at polar latitudes we co-estimate, together with the model of the core, lithospheric and large-scale magnetospheric fields, a magnetic potential that depends on quasi-dipole latitude and magnetic local time.

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“…We analyse Level 1b magnetic data 3 that according to ESA nomenclature are called SW_OPER_MAGx_LR_1B (x = A, B, C) with file counter equal to 0405, in particular measurements rotated in the NEC (North-East-Centre) frame. This version of Swarm vector data is corrected for a disturbance likely due to the position of the Sun with respect to Swarm satellites (details can be found in Lesur et al 2015).…”

Section: Data Reprocessingmentioning

confidence: 99%

Unmodelled magnetic contributions in satellite-based models

2016

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A complex system of electric currents flowing in the ionosphere and magnetosphere originates from the interaction of the solar wind and the Interplanetary Magnetic Field (IMF) with the Earth's magnetic field. These electric currents generate magnetic fields contributing themselves to those measured by both ground observatories and satellites. Here, low-resolution (1 Hz) magnetic vector data recorded between 1 March 2014 and 31 May 2015 by the recently launched Swarm constellation are considered. The core and crustal magnetic fields and part of that originating in the magnetosphere are removed from Swarm measurements using CHAOS-5 model. Low-and mid-latitude residuals of the geomagnetic field representing the ionospheric and the unmodelled magnetospheric contributions are investigated, in the Solar Magnetic frame, according to the polarity of IMF B y (azimuthal) and B z (north-south) components and to different geomagnetic activity levels. The proposed approach makes it possible to investigate the features of unmodelled contributions due to the external sources of the geomagnetic field. Results show, on one side, the existence of a relation between the analysed residuals and IMF components B y and B z , possibly due to the long distance effect of high-latitude field-aligned currents. On the other side, they suggest the presence of a contribution due to the partial ring current that is activated during the main phase of geomagnetic storms. The perturbation observed on residuals is also compatible with the effect of the net field-aligned currents. Moreover, we have quantitatively estimated the effect of these current systems on computed residuals.

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Parent magnetic field models for the IGRF-12GFZ-candidates

Cited by 39 publications

References 15 publications

An annual proxy for the geomagnetic signal of magnetospheric currents on Earth based on observatory data from 1900–2010

An annual proxy for the geomagnetic signal of magnetospheric currents on Earth based on observatory data from 1900–2010

A model of Earth’s magnetic field derived from 2 years of Swarm satellite constellation data

Unmodelled magnetic contributions in satellite-based models

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