NDLI: Geomagnetic Core Field Secular Variation Models

Content Provider	Springer Nature Link
Author	Gillet, N. Lesur, V. Olsen, N.
Copyright Year	2009
Abstract	We analyse models describing time changes of the Earth’s core magnetic field (secular variation) covering the historical period (several centuries) and the more recent satellite era (previous decade), and we illustrate how both the information contained in the data and the a priori information (regularisation) affect the result of the ill-posed geomagnetic inverse problem. We show how data quality, frequency and selection procedures govern part of the temporal changes in the secular variation norms and spectra, which are sometimes difficult to dissociate from true changes of the core state. We highlight the difficulty of resolving the time variability of the high degree secular variation coefficients (i.e. the secular acceleration), arising for instance from the challenge to properly separate sources of internal and of external origin. In addition, the regularisation process may also result in artificial changes in the model norms and spectra. Model users should keep in mind that such features can be mis-interpreted as the signature of physical mechanisms (e.g. diffusion). Finally, we present perspectives concerning core field modelling: imposing dynamical constraints (e.g. by means of data assimilation) reduces the non-uniqueness of the geomagnetic inverse problem.
Starting Page	129
Ending Page	145
Page Count	17
File Format	PDF
ISSN	00386308
Journal	Space Science Reviews
Volume Number	155
Issue Number	1-4
e-ISSN	15729672
Language	English
Publisher	Springer Netherlands
Publisher Date	2009-12-15
Publisher Place	Dordrecht
Access Restriction	One Nation One Subscription (ONOS)
Subject Keyword	Astrophysics and Astroparticles Aerospace Technology and Astronautics Planetology Extraterrestrial Physics, Space Sciences
Content Type	Text
Resource Type	Article
Subject	Astronomy and Astrophysics Space and Planetary Science

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1	Ministry of Education (GoI), Department of Higher Education	Sanctioning Authority	https://www.education.gov.in/ict-initiatives
2	Indian Institute of Technology Kharagpur	Host Institute of the Project: The host institute of the project is responsible for providing infrastructure support and hosting the project	https://www.iitkgp.ac.in
3	National Digital Library of India Office, Indian Institute of Technology Kharagpur	The administrative and infrastructural headquarters of the project	Dr. B. Sutradhar bsutra@ndl.gov.in
4	Project PI / Joint PI	Principal Investigator and Joint Principal Investigators of the project	Dr. B. Sutradhar bsutra@ndl.gov.in Prof. Saswat Chakrabarti will be added soon
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