TITLE:
Residual Magnetic Anomalies Mapping from CHAMP Observations
AUTHORS:
M. C. Berguig, S. Bouraoui, Y. Cohen
KEYWORDS:
Magnetic Field, Lithospheric Anomalies, External Field, CHAMP Measurements, Remanent Magnetization
JOURNAL NAME:
International Journal of Geosciences,
Vol.7 No.5,
May
18,
2016
ABSTRACT: CHAMP high-quality vector
magnetometer observations collected from July 2000 to September 2010 have been
used to map the residual vector magnetic anomaly fields. This field is so
called the lithospheric magnetic field which is the result of two contributions
of the induced and the remanent magnetization. It is therefore essential to
study the magnetic properties of the crustal rocks. Isolating this field from
the other contributions, interpreting and even defining are however difficult
and still debated. We investigate how to identify and separate the lithospheric
vector magnetic field ΔX, ΔY and
ΔZ from other
contributions. For this purpose we use selected night magnetic data from which
we remove a model field of degree 16 and external model field of degree 2
developed by spherical harmonics analysis. Concerning the induced lithospheric
field which is assumed to be aligned with the internal dipole was also removed.
To minimize the secular variation effects, we calculated internal models for
each two months. The method developed here has been successfully applied to
isolate lithospheric field produced by remanent magnetizations from CHAMP
satellite data. The resolution and altitude measurements make it very hard to
map short wavelength crustal magnetic anomalies. The large-scale strong
magnetic anomalies detected using this technique are in agreement with previous
global magnetic maps. These anomalies appear with an amplitude of about 10 nT
at satellite altitude such as Bangui’s anomaly.