International Geomagnetic Reference Field: The Seventh Generation

Barton, C. E.

doi:10.5636/jgg.49.123

Cited by 147 publications

(105 citation statements)

References 24 publications

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“…The most commonly used global ®eld model is the International Geomagnetic Reference Field (IGRF) (Barton, 1997). The Hermanus Magnetic Observatory (HMO), like similar institutions in other countries, generates a number of regional geomagnetic ®eld models.…”

Section: Geomagnetic ®Eld Modelsmentioning

confidence: 99%

The development of a regional geomagnetic daily variation model using neural networks

Sutcliffe¹

2000

Ann. Geophys.

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Abstract. Global and regional geomagnetic ®eld models give the components of the geomagnetic ®eld as functions of position and epoch; most utilise a polynomial or Fourier series to map the input variables to the geomagnetic ®eld values. The only temporal variation generally catered for in these models is the long term secular variation. However, there is an increasing need amongst certain users for models able to provide shorter term temporal variations, such as the geomagnetic daily variation. In this study, for the ®rst time, arti®cial neural networks (ANNs) are utilised to develop a geomagnetic daily variation model. The model developed is for the southern African region; however, the method used could be applied to any other region or even globally. Besides local time and latitude, input variables considered in the daily variation model are season, sunspot number, and degree of geomagnetic activity. The ANN modelling of the geomagnetic daily variation is found to give results very similar to those obtained by the synthesis of harmonic coe cients which have been computed by the more traditional harmonic analysis of the daily variation.

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Section: Geomagnetic ®Eld Modelsmentioning

confidence: 99%

The development of a regional geomagnetic daily variation model using neural networks

Sutcliffe¹

2000

Ann. Geophys.

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“…In the following discussion we define the apparent source region to be the unique location along the line of sight of the DOA where 2fee is equal to the observed frequency. In this work the IGRF model [Barton, 1997] is used to determine 2fc• as a function of geomagnetic latitude and longitude. Of course, the location of this apparent source region may differ from the actual source region due to differences between the local geomagnetic field and the IGRF model or as a result of refraction as the wave propagates through the ionosphere.…”

Section: Observed Doasmentioning

confidence: 99%

Statistical and case studies of 2f_ce auroral roar observed with a medium frequency interferometer

Hughes¹,

LaBelle²,

Watermann³

2001

J. Geophys. Res.

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Abstract. The medium frequency interferometer (MFI) is the first direction-sensitive instrument to observe auroral radio emissions in the frequency range 2500-3000 kHz. The MFI has observed many auroral roar events since operations began at the Sondrestrom Research Facility near Kangerlussuaq, Greenland, in April 1999. The MFI data reveal that individual auroral roar events often propagate to the MFI from multiple directions and that the source locations show interesting time-variable features such as drifting and oscillations with a period of a few minutes in both azimuth and zenith angles. Most events have a direction of arrival from the local magnetic south, with the latitude distribution of the apparent source regions peaked near the poleward edge of the statistical auroral oval. The altitude distribution of apparent source locations has a bimodal form, which may be interpreted as evidence for two distinct well-separated sources, one on the topside F region and one on the bottomside.

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“…The In ter na tional Geo mag netic Ref er ence Field (IGRF), for the field of in ter nal or i gin and its sec u lar vari a tion (Regan and Cain 1975;Barton 1997), was pro mul gated by the In ter national As so ci a tion of Geo mag ne tism and Aeronomy (IAGA) Com mis sion 2. A global model of the ref er ence field is calcu lated by:…”

Section: Mag Netic Sur Vey and Re Duc Tionsmentioning

confidence: 99%

Magnetic Survey of Taiwan and Its Preliminary Interpretations

Yen¹,

Chen²,

Hsieh³

et al. 2009

Terr. Atmos. Ocean. Sci.

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AB STRACTTo achieve an im proved over all un der stand ing of the tec ton ics of Tai wan, an is land-wide mag netic sur vey, es pe cially in the mostly in ac ces si ble moun tain ranges, was car ried out from July 2003 to Feb ru ary 2004. In to tal, 6063 mag netic points were sur veyed at an av er age spac ing of 2 km. Af ter data re duc tions, a new mag netic anom aly map of Tai wan was con structed. The map shows the range of mag netic anom a lies mostly dis trib ut ing be tween -400 to 400 nT. Anom a lies in the south ern part of Tai wan are much higher than those in the north whilst anom a lies in the west ern plains area are higher than those of the mountain ranges.High-fre quency mag netic anom a lies, gen er ally more com plex and lo cal ized, are found in west cen tral (south of 24°N) and south west ern Tai wan. Smooth and gen tle mag netic anom a lies lie over a ma jor part of the moun tain ranges, ex cept in the south ern seg ment of the Cen tral Range. Ac cord ing to the am pli tude of mag netic anom a lies and their cov er age, this im plies that a broad ex tru sive ultramafite body could ex ist be neath the south ern segment of the Central Range.

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International Geomagnetic Reference Field: The Seventh Generation

Cited by 147 publications

References 24 publications

The development of a regional geomagnetic daily variation model using neural networks

The development of a regional geomagnetic daily variation model using neural networks

Statistical and case studies of 2f_ce auroral roar observed with a medium frequency interferometer

Magnetic Survey of Taiwan and Its Preliminary Interpretations

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International Geomagnetic Reference Field: The Seventh Generation

Cited by 147 publications

References 24 publications

The development of a regional geomagnetic daily variation model using neural networks

The development of a regional geomagnetic daily variation model using neural networks

Statistical and case studies of 2fce auroral roar observed with a medium frequency interferometer

Magnetic Survey of Taiwan and Its Preliminary Interpretations

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Product

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Statistical and case studies of 2f_ce auroral roar observed with a medium frequency interferometer