Information content and K-entropy of the present geomagnetic field

Santis, Angelo De; Tozzi, Roberta; Gaya–Piqué, Luis R.

doi:10.1016/s0012-821x(03)00681-2

Cited by 22 publications

(43 citation statements)

References 25 publications

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“…In the last 25 yr, some papers have appeared suggesting that an imminent reversal could occur (e.g., De Santis et al, 2004 and the references therein). The recent dipole decrease is considered part of a trend that has continued for the last 2000 yr (Merrill and McElhinny, 1983) and a more rapid poleward drift of the dipole axis in the past 50 yr has also been suggested (Amit et al, 2010).…”

Section: Introductionmentioning

confidence: 99%

Toward a possible next geomagnetic transition?

Santis

Qamili

2013

Nat. Hazards Earth Syst. Sci.

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Abstract. The geomagnetic field is subject to possible reversals or excursions of polarity during its temporal evolution. Considering that: (a) in the last 83 million yr the typical average time between one reversal and the next (the so-called chron) is around 400 000 yr, (b) the last reversal occurred around 780 000 yr ago, (c) more excursions (rapid changes in polarity) can occur within the same chron and (d) the geomagnetic field dipole is currently decreasing, a possible imminent geomagnetic reversal or excursion would not be completely unexpected. In that case, such a phenomenon would represent one of the very few natural hazards that are really global. The South Atlantic Anomaly (SAA) is a great depression of the geomagnetic field strength at the Earth's surface, caused by a reverse magnetic flux in the terrestrial outer core. In analogy with critical point phenomena characterized by some cumulative quantity, we fit the surface extent of this anomaly over the last 400 yr with power law or logarithmic functions in reverse time, also decorated by logperiodic oscillations, whose final singularity (a critical point t c ) reveals a great change in the near future (2034 ± 3 yr), when the SAA area reaches almost a hemisphere. An interesting aspect that has recently been found is the possible direct connection between the SAA and the global mean sea level (GSL). That the GSL is somehow connected with SAA is also confirmed by the similar result when an analogous critical-like fit is performed over GSL: the corresponding critical point (2033 ± 11 yr) agrees, within the estimated errors, with the value found for the SAA. From this result, we point out the intriguing conjecture that t c would be the time of no return, after which the geomagnetic field could fall into an irreversible process of a global geomagnetic transition that could be a reversal or excursion of polarity.

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Section: Introductionmentioning

confidence: 99%

Toward a possible next geomagnetic transition?

Santis

Qamili

2013

Nat. Hazards Earth Syst. Sci.

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“…This started a discussion about a forthcoming next inversion (polarity change), although field models in the scale of millennia show several periods of intensity decrease. Definite arguments that the present intensity decrease leads directly to dipole inversion and will not change to increase in the near future do not exist so far (Constable and Korte, 2006;De Santis et al, 2004).…”

Section: Magnetic Field Fadingmentioning

confidence: 99%

Alexander von Humboldt's charts of the Earth's magnetic field: an assessment based on modern models

Mandea

Korte

Soloviev

et al. 2010

Hist. Geo Space. Sci.

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Abstract. The 19th century witnessed a resurgence of interest in Earth's magnetic field. Both observational and theoretical aspects were involved, and one of the emblematic figures of this period was Alexander von Humboldt. Throughout a long life he maintained a strong interest in a broad area of subjects, however, here we are interested in his role in geomagnetism, and particularly in his pioneering contributions to charting the geomagnetic field. Alexander von Humboldt efforts in measuring and charting the Earth's magnetic field are recounted and the maps of declination, inclination and total intensity he had prepared are compared, favorably, with maps for the same epoch based on a modern model of the geomagnetic field, gufm1. This modern assessment of the accuracy of von Humboldt's geomagnetic charts illustrates the importance of his work, being also our homage to the 150th anniversary of the death of Alexander von Humboldt.

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“…Some investigators (e.g. De Santis et al, 2004) have speculated that this rapid decrease would be of global relevance implying the development of a dipole reversal as has happened several times in the Earth's history, but others have denied this possibility (Gubbins et al, 2006).…”

Section: Secular Variation and Geomagnetic Jerks In Antarcticamentioning

confidence: 99%

The contribution of geomagnetic observatories and magnetic models to the study of secular variation and jerks in Antarctica

Meloni¹,

Cafarella²,

Michelis³

et al. 2007

Open-File Report

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Some of the most interesting features of the geomagnetic field and its time variations are displayed in polar areas. Observatory monthly means usually provide an excellent opportunity to study the temporal changes of the magnetic field at a given location. Unfortunately, on the Antarctic continent the distribution of the permanent groundbased observatories does not permit a uniform coverage of the examined area. Furthermore, the magnetic records are characterized by intense external disturbances and noise that make the analysis of the magnetic field difficult. To improve our knowledge of the secular variation and detect the presence of secular variation impulses (geomagnetic jerks) in Antarctica, we use both observatory data and the CM4 quiet time magnetic field model. In particular CM4 improves our knowledge of geomagnetic jerks over Antarctica through the study of the sign changes of the secular acceleration maps.

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Information content and K-entropy of the present geomagnetic field

Cited by 22 publications

References 25 publications

Toward a possible next geomagnetic transition?

Toward a possible next geomagnetic transition?

Alexander von Humboldt's charts of the Earth's magnetic field: an assessment based on modern models

The contribution of geomagnetic observatories and magnetic models to the study of secular variation and jerks in Antarctica

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