scholarly journals Indonesian Earth’s Lithospheric Magnetic Field modelling using Spherical Cap Harmonic Analysis Method

2021 ◽  
Vol 873 (1) ◽  
pp. 012030
Author(s):  
Ilham ◽  
M Syirojudin ◽  
R Margiono ◽  
A Marsono ◽  
N Ardiana
Keyword(s):  
Magnetic Field ◽  
Harmonic Analysis ◽  
Magnetic Data ◽  
Spherical Cap ◽  
Crust And Upper Mantle ◽  
Repeat Station ◽  
Station Data ◽  
Lithospheric Magnetic Field ◽  
Spherical Cap Harmonic Analysis ◽  
Swarm Satellite

Abstract The earth’s lithospheric magnetic field is part of the main earth’s magnetic field. The lithospheric field has a very small value compared to the Earth’s main magnetic field, approximately less than 1%, and this field is generated at the earth’s crust and upper mantle. Modelling of lithospheric field is useful mainly for predicting the distribution of the value of lithospheric fields and to determine the magnetic anomaly. In this research, modelling the Earth’s lithospheric magnetic field uses Spherical Cap Harmonic Analysis (SCHA) method and this method can do modelling using regional magnetic data. The data used for the modelling are magnetic repeat station data in Indonesia region (BMKG’s Epoch) and SWARM satellite data. The results of the modelling using integrated SWARM satellite and repeat station data produce RMSE values of 64.0834 nT and the expansion of index K is 70. In addition, the results of the modelling resolution is 1.50. The value’s range of modelling’s result are -987.192 – 998.239 nT for X component, -968.189 – 949.438 nT for Y component, -981.266 – 608.676 nT for Z component, and -904.151 – 997.389 nT for total intensity are.

scholarly journals Regional geomagnetic field modelling: the contribution of the Istituto Nazionale di Geofisica

1997 ◽  
Vol 40 (5) ◽  
Author(s):  
A. De Santis ◽  
M. Chiappini ◽  
G. Dominici ◽  
A. Meloni
Keyword(s):  
Magnetic Field ◽  
Harmonic Analysis ◽  
Geomagnetic Field ◽  
Spherical Harmonic Analysis ◽  
Spherical Cap ◽  
Field Modelling ◽  
Term Basis ◽  
Time Variations ◽  
Spherical Cap Harmonic Analysis ◽  
Cap Analysis

Models of the geomagnetic field are mathematical expressions able to represent the Earth's magnetic field space and time variations. Time variations on the long term basis are represented by the so-called secular variation. This paper describes and reviews recent activities of the Italian group at the Istituto Nazionale di Geofisica in regional magnetic field modelling. The models are introduced starting from the classical technique of Spherical Harmonic Analysis (SHA) undertaken for the first time by Gauss, the polynomial analysis and the regional harmonic analysis, specifically introduced as a regional analogue of SHA. In this last group the recent techniques of Spherical Cap Harmonic Analysis (SCHA), Translated Origin Spherical Cap Analysis (TOSCA) and Adjusted Spherical Cap Harmonic Analysis (ASHA) are also described and discussed.

scholarly journals Development of an improved geomagnetic reference field of Antarctica

1999 ◽  
Vol 42 (2) ◽  
Author(s):  
A. De Santis ◽  
M. Chiappini ◽  
J. M. Torta ◽  
R. R. B. von Frese
Keyword(s):  
Magnetic Field ◽  
Secular Variation ◽  
Reference Model ◽  
Reference Field ◽  
Spherical Cap ◽  
Core Field ◽  
The Core ◽  
Spherical Cap Harmonic Analysis ◽  
The Antarctic ◽  
Magnetic Observatories

The properties of the Earth's core magnetic field and its secular variation are poorly known for the Antarctic. The increasing availability of magnetic observations from airborne and satellite surveys, as well as the existence of several magnetic observatories and repeat stations in this region, offer the promise of greatly improving our understanding of the Antarctic core field. We investigate the possible development of a Laplacian reference model of the core field from these observations using spherical cap harmonic analysis. Possible uses and advantages of this approach relative to the implementations of the standard global reference field are also considered.

scholarly journals Repeat station data compared to a global geomagnetic field model

2013 ◽  
Vol 55 (6) ◽  
Author(s):  
Monika Korte ◽  
Vincent Lesur
Keyword(s):  
Magnetic Field ◽  
Secular Variation ◽  
Global Model ◽  
Time Interval ◽  
Night Time ◽  
Core Field ◽  
Repeat Station ◽  
Station Data ◽  
Long Term Trends

<p>Geomagnetic repeat station surveys with local variometers for improved data reductions have been carried out in Germany for about ten years. For nearly the same time interval the satellites Ørsted and CHAMP have provided a good magnetic field data coverage of the whole globe. Recent global field models based on these satellite data together with geomagnetic observatory data provide an improved description of the core field and secular variation. We use the latest version of the GFZ Reference Internal Magnetic Model to compare the magnetic field evolution predicted by that model between 2001 and 2010 to the independent repeat station data collected over the same time interval in Germany. Estimates of crustal bias at the repeat station locations are obtained as averages of the residuals, and the scatter or trend around each average provides information about influences in the data from field sources not (fully) described by the global model. We find that external magnetic field signal in the order of several nT, including long-term trends, remains both in processed annual mean and quiet night time repeat station data. We conclude that the geomagnetic core field secular variation in this area is described to high accuracy (better than 1 nT/yr) by the global model. Weak long-term trends in the residuals between repeat station data and the model might indicate induced lithospheric anomalies, but more data are necessary for a robust analysis of such signals characterized by very unfavorable signal-to-noise ratio.</p>

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