Equivalent Monopole Source of the Geomagnetic South Atlantic Anomaly

Santis, Angelo De; Qamili, Enkelejda

doi:10.1007/s00024-009-0020-5

Cited by 14 publications

(10 citation statements)

References 31 publications

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“…This is consistent with most of the results of De Santis (2007,2008) who, analysing the past 400 years from the GUFM1 model, found that the information content of the geomagnetic field started to decay between 1700 and 1800, and it is still decaying (De Santis et al, 2004). Other possible recent confirmations of the present transitional state of the geomagnetic field could be the complex dynamics over the past 400 years of the South Atlantic Anomaly (De Santis and Qamili, 2010), a huge depression of the geomagnetic field strength in the Southern Hemisphere that could go to zero by a few hundreds of years, and the recent detection of rapidly changing dynamics in the Earth's fluid core from satellite data with timescales less than 1 year (Olsen and Mandea, 2008).…”

Section: Discussionsupporting

confidence: 90%

Shannon information of the geomagnetic field for the past 7000 years

Santis

Qamili

2010

Nonlin. Processes Geophys.

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Abstract. The present behaviour of the geomagnetic field as expressed by the International Geomagnetic Reference Field (IGRF) deserves special attention when compared with that shown over the past few thousands of years by two paleomagnetic/archeomagnetic models, CALS3K and CALS7K. The application of the Information theory in terms of Shannon Information and K-entropy to these models shows characteristics of an instable geomagnetic field. Although the result is mitigated when we correct the CALS7K model for its typical spectral damping, the present geomagnetic field as represented by IGRF is still rather distinct, at least for the past 4000 years, a result that is further confirmed by the CALS3K model. This is consistent with a significant global critical state started at around 1750, and still present, characterised by significant decays of the geomagnetic dipole, energy and Shannon information and high K-entropy. The details of how these characteristics may develop are not clear, since the present state could move toward an excursion or a geomagnetic polarity reversal, but we cannot exclude the possibility that the "critical" behaviour will become again more "normal", stopping the apparent trend of the recent geomagnetic field decay.

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Section: Discussionsupporting

confidence: 90%

Shannon information of the geomagnetic field for the past 7000 years

Santis

Qamili

2010

Nonlin. Processes Geophys.

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“…The “specks” of higher misfit visible over the Pacific, as well as the higher‐misfit area over South America, are due to UARS, as can be seen in Figure 3. The South Atlantic Anomaly contributes to the general higher misfit over South America [ De Santis and Qamili , 2010], but the response of UARS is much greater than that of the other satellites. A map is also shown with the misfit from the 11th generation in quiet geomagnetic conditions, corresponding to a planetary Kp index at most 2.…”

Section: Results and Analysismentioning

confidence: 99%

Ionosphere geomagnetic field: Comparison of IGRF model prediction and satellite measurements 1991–2010

Matteo

Morton

2011

Radio Science

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[1] The geomagnetic field is an important parameter in space physics. The International Geomagnetic Reference Field (IGRF) is a model of the Earth's main field. Current sources in the ionosphere, the interplanetary magnetic field, annual and diurnal variation, and other sporadic and unmodeled effects may alter the actual B field distribution. We investigate whether the model is nevertheless sufficiently accurate for computing ionospheric effects on radio frequency signals. Detailed analysis of scalar intensity is presented based on direct measurements of the magnetic field taken from UARS, SAC-C, Ørsted, and CHAMP, all satellites with magnetometers orbiting between 200 and 1000 km altitude. Our results indicate that the IGRF model is within 1% accuracy of the measured ionosphere B field, 92.80% of the time. Quality control issues associated with the scalar data are also discussed.

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“…The existence of the SAA is linked closely with the geomagnetic field distribution (Heynderickx, 1996). From the high atmosphere and close outer space, the SAA is seen as a sort of geomagnetic hole where electric and neutral particles can flow from the Van Allen belts and from the magnetosphere into the atmosphere below (De Santis and Qamili, 2010).…”

Section: Introductionmentioning

confidence: 97%

Characterization of the South Atlantic Anomaly

Nasuddin

Abdullah

Hamid

2019

Nonlin. Processes Geophys.

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Abstract. This research intends to characterize the South Atlantic Anomaly (SAA) by applying the power spectrum analysis approach. The motivation to study the SAA region is due to its nature. A comparison was made between the stations in the SAA region and outside the SAA region during the geomagnetic storm occurrence (active period) and the normal period where no geomagnetic storm occurred. The horizontal component of the data of the Earth's magnetic field for the occurrence of the active period was taken on 11 March 2011 while for the normal period it was taken on 3 February 2011. The data sample rate used is 1 min. The outcome of the research revealed that the SAA region had a tendency to be persistent during both periods. It can be said that the region experiences these characteristics because of the Earth's magnetic field strength. Through the research, it is found that as the Earth's magnetic field increases, it is likely to show an antipersistent value. This is found in the high-latitude region. The lower the Earth's magnetic field, the more it shows the persistent value as in the middle latitude region. In the region where the Earth's magnetic field is very low like the SAA region it shows a tendency to be persistent.

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Equivalent Monopole Source of the Geomagnetic South Atlantic Anomaly

Cited by 14 publications

References 31 publications

Shannon information of the geomagnetic field for the past 7000 years

Shannon information of the geomagnetic field for the past 7000 years

Ionosphere geomagnetic field: Comparison of IGRF model prediction and satellite measurements 1991–2010

Characterization of the South Atlantic Anomaly

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