scholarly journals Spherical Harmonic Analysis of the Earth's Magnetic Field, Applied to a Limited Part of the World

1969 ◽  
Vol 21 (4) ◽  
pp. 751-756 ◽  
Author(s):  
Maurice Aubert
Keyword(s):  
Magnetic Field ◽  
Harmonic Analysis ◽  
Spherical Harmonic ◽  
Spherical Harmonic Analysis ◽  
Earth’S Magnetic Field ◽  
The World ◽  
Earth's Magnetic Field

The Earth's magnetic field variations at the Algerian magnetic observatory of Tamanrasset from 1932 to 2020.

2021 ◽  
Author(s):  
Lemgharbi Abdenaceur ◽  
Hamoudi Mohamed ◽  
Abtout Abdeslam ◽  
Abdelhamid Bendekken ◽  
Ener Aganou ◽  
...  
Keyword(s):  
Magnetic Field ◽  
International Association ◽  
Sampling Rate ◽  
Magnetic Data ◽  
Magnetic Observatory ◽  
Earth’S Magnetic Field ◽  
Data Set ◽  
Secular Variations ◽  
The World ◽  
Earth's Magnetic Field

<p>In order to understand the spatial and temporal behavior of the Earth's magnetic field, scientists, following C.F. Gauss initiative in 1838 have established observatories around the world. More than 200 observatories aiming to continuously record, the time variations of the magnetic field vector and to maintain the best standard of the accuracy and resolution of the measurements.</p><p>This study focused on the acquisition and analysis of the magnetic data provided by the Algerian magnetic observatory of Tamanrasset (labelled TAM by the International Association of Geomagnetism and Aeronomy). This observatory is located in southern Algeria at 5.53°E longitude, 22.79°N Latitude. Its altitude is 1373 meters above msl. TAM is continuously running since 1932, using old brand variometers, like Mascart and La Cour with photographic recording at the very beginning. Nowadays modern electronic equipment are used in the framework of INTERMAGNET project. Very large geomagnetic database collected over a century is available. We will describe the history and the various improvement of the methods and instrumentation.</p><p>Preliminary analysis of time series of the observatory data allowed to distinguish two kinds of data: the first type, with low resolution, collected between 1932 and 1992. This data set comes from the annual, monthly, daily and hourly means. The second one with high resolution is represented by minutes and seconds sampling rate since 1993 when TAM was integrated to the world observatory network, INTERMAGNET. Part of the second dataset contains many gaps. We try to fill these gaps thanks to mathematical methods. Absolute measurements and repeat station data allow better accuracy in the secular variations and an improved regional model.</p><p>Keywords: TAM observatory, temporal variation, terrestrial magnetic field, secular variations, INTERMAGNET.</p>

scholarly journals The electric and magnetic state of the interior of the earth, as inferred from terrestrial magnetic variations

1930 ◽  
Vol 229 (670-680) ◽  
pp. 427-460 ◽  
Keyword(s):  
Magnetic Field ◽  
Harmonic Analysis ◽  
Spherical Harmonic ◽  
Major Part ◽  
Inner Core ◽  
Magnetic State ◽  
Spherical Harmonic Analysis ◽  
Conducting Sphere ◽  
The Earth ◽  
Magnetic Variation

1.1. By spherical harmonic analysis it is possible, as was shown by GAUSS, to distinguish between the parts of the earth’s magnetic field, at any time, which originate respectively within and above the earth’s surface. In this way GAUSS confirmed and extended GILBERT’s conclusion that the field is almost entirely of internal origin. 1.2. Sir ARTHUR SCHUSTER applied the method to the field of the daily magnetic variation at the earth’s surface, and found that the major part is of external origin, but that there is also a part produced within the earth. He attributed the latter to electric currents induced in the earth by the outer varying field, which he regarded as primary. In co-operation with Prof. H. LAMB he showed that the relation between the two parts of the field is consistent with this hypothesis ; the calculations referred to currents induced in a uniformly conducting sphere. They showed that the conducting sphere must be distinctly smaller than the earth, that is, it is an inner core, and not the whole earth, which is effective.

The Atlas of the Earth's Magnetic Field

2012 ◽  
Author(s):  
A. Soloviev ◽  
A. Khokhlov ◽  
E. Jalkovsky ◽  
A. Berezko ◽  
A. Lebedev ◽  
...  
Keyword(s):  
Magnetic Field ◽  
Earth’S Magnetic Field ◽  
Earth's Magnetic Field
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