Abstract
Abstract The linearity of the secular variation of the Earth’s magnetic field is irregularly broken by sudden changes in its trend, known as geomagnetic jerks. Detecting these events in the temporal variations of the magnetic field components continues to be an exciting topic, mainly recently when their investigation rely not more only on observatory data, but as well as on measurements provided by satellites. We have also been interested by these magnetic events, and one of the central aims of our work has been to determine whether the satellite scalar data, obtained in the sixties and early seventies are able to reveal the existence of such a geomagnetic jerk, previously detected around 1969, in observatory annual or monthly means. For this purpose, we have used available OGO2, OGO4 and OGO6 satellite intensity data covering the period 1965–1971. Another motivation of re-processing and analyzing these old satellite datasets has been to better estimate their role in the global core field modeling, especially in describing the secular variation. Our results indicate that these ancient magnetic satellite datasets contain valuable information to characterize the secular variation over the time-span they are available, and allow to detect the geomagnetic jerk around 1969.
Highlights
The measured geomagnetic field is the result of internal and external sources, with respect of the Earth’s surface
One main objective of our work is to study whether the satellite scalar data obtained in the mid-sixties and early seventies are able to evidence the existence of such geomagnetic jerks
The first one, direct, from temporal series of observatory and satellite data and the second one, indirect, through global spherical harmonics field models, based on POGO data, only. 3.1 Direct secular variation study: temporal series from observatories and scalar satellites To carry out this study we have considered the approach proposed by Mandea and Olsen (2006) to build “virtual observatory” series from satellite available data over the real observatory locations
Summary
The measured geomagnetic field is the result of internal and external sources, with respect of the Earth’s surface. The magnetic field, at an arbitrary location at the Earth’s surface, is the sum of the core and lithospheric fields, as internal contributions, and of the ionospheric and magnetospheric fields, as external contributions. To these main sources one can add the magnetic field induced in the crust and the upper mantle by geomagnetic field external variations (see for more details Mandea and Purucker, 2005). The fluid motion generates electric currents, which maintain a magnetic field. Such a phenomenon is known as a self-sustaining dynamo. The magnitude of this field, at the Earth’s surface, ranges between approximately 30000 nanoTeslas (nT) in the equatorial regions (with minimum values around 20000 nT for the South Atlantic Anomaly), and about 70000 nT in the magnetic pole areas (Mandea et al, 2007)
Sign-in/Register to view highlights & summary Sign-in/Register to access full text options 
Talk to us
Join us for a 30 min session where you can share your feedback and ask us any queries you have
Schedule a callDisclaimer: All third-party content on this website/platform is and will remain the property of their respective owners and is provided on "as is" basis without any warranties, express or implied. Use of third-party content does not indicate any affiliation, sponsorship with or endorsement by them. Any references to third-party content is to identify the corresponding services and shall be considered fair use under The CopyrightLaw.
