Magnetic poles and dipole tilt variation over the past decades to millennia

Introduction

Supplementary material for EPS article "Magnetic poles and dipole tilt variation over the past decades to millennia" by M. Korte and M. Mandea. The material consists of:  

  • the geomagnetic and magnetic pole locations from 7000 BC to A.D. 2006.6
  • mpeg animations showing the changes of the poles and the radial geomagnetic field centered on the northern and southern hemisphere respectively.

The position of the magnetic poles is mainly of interest at the Earth's surface, while we investigate the field morphology generating these poles at the CMB. The animations show the radial field at the CMB with the TC indicated by a circle. For reference, the continent outlines are overlain, and these and the TC circle represent the area at the Earth's surface which is influenced by the respective areas of the core field if we assume no significant influences across the borders of a cone from the center of the Earth. This allows us to include the position of the magnetic poles at the Earth's surface in the same figures.

The data basis are published continuous geomagnetic field models covering different time intervals. North and south geomagnetic and magnetic pole locations were determined from these models. For the animations, model predictions were calculated on a regular global grid in evenly spaced time intervals and displayed as color-coded contour plots. Positions of magnetic and geomagnetic poles at the Earth's surface and the trace of the inner core tangent cylinder at the core-mantle boundary are superposed.

Producing grid values from model coefficients and plotting were done using the programs magmap and color by R.L. Parker.

Individual plots were combined to animations using the Berkely mpeg encoder.

References

  • Korte, M. and M. Mandea, Magnetic poles and dipole tilt variation over the past decades to millennia, Earth Planets Space, 60, 937-948, 2008.
  • Jackson, A., A. Jonkers, and M. Walker (2000), Four centuries of geomagnetic secular variation from historical records, Phil. Trans. R. Soc. Lond. A, 358, 957-990.
  • Korte, M. and C.G. Constable (2005): Continuous geomagnetic field models for the past 7 millennia: 2. CALS7K. Geochem., Geophys., Geosys. , 6(2), Q02H15, doi:10.1029/2004GC000801. (Model available at EarthRef.org digital archive or CALS7K Model site of GFZ Potsdam).
  • Sabaka, T.J., N. Olsen, and M.E. Purucker (2004), Extending comprehensive models of the Earth's magnetic field with Ørsted and CHAMP data, Geophys. J. Int., 159, 521-547. (Model available at GSFC NASA).
  • Olsen, N., H. Lühr, T.J. Sabaka, M. Mandea, M. Rother, L. Toffner-Clausen and S. Choi (2006): CHAOS - A model of the Earth's magnetic field derived from CHAMP, OØrsted and SAC-C magnetic satellite data. Geophys. J. Int., 166, 67-75. (Model available at CHAOS Model site of GFZ Potsdam).

 

Download

FileFormatSizeDateContents
CHAOS_poles zipped ASCII data0,7KBMar 2008Geographic latitudes and longitudes of north and south geomagnetic and magnetic poles from CHAOS model (Olsen et al., 2006).
CM4_poles.zip zipped ASCII data1,2KBMar 2008Geographic latitudes and longitudes of north and south geomagnetic and magnetic poles from CM4 model (Sabaka et al., 2004).
GUFM1_poles.zipzipped ASCII data7.0KBMar 2008Geographic latitudes and longitudes of north and south geomagnetic and magnetic poles from gufm1 model (Jackson et al., 2000).
CALS7K.2_poles.zip zipped ASCII data78KBMar 2008Geographic latitudes and longitudes of north and south geomagnetic and magnetic poles from CALS7K.2 model (Korte and Constable, 2005).
Br_CM4_N.mpg Video stream data 1,7MBOkt 2007Animation: Radial magnetic field at the core-mantle boundary from the CM4 model [Sabaka et al., 2004] for the northern hemisphere with locations of magnetic (yellow star) and geomagnetic (green cross) poles at the Earth's surface. The rotation axis, i.e. geographic pole is marked by a black dot, the inner core tangent cylinder at the core-mantle boundary or projected to the Earth's surface by a white circle.Scalar data and model predictions.
Br_CM4_S.mpg Video stream data1.4MBOkt 2007Animation: Radial magnetic field at the core-mantle boundary from the CM4 [Sabaka et al., 2004] model for the southern hemisphere with locations of magnetic (yellow star) and geomagnetic (green cross) poles at the Earth's surface. The rotation axis, i.e. geographic pole is marked by a black dot, the inner core tangent cylinder at the core-mantle boundary or projected to the Earth's surface by a white circle.
Br_gufm1_N.mpgVideo stream data7.2MBOkt 2007Animation: Radial magnetic field at the core-mantle boundary from the gufm1 model [Jackson et al., 2000] for the northern hemisphere with locations of magnetic (yellow star) and geomagnetic (green cross) poles at the Earth's surface. The pole marks have tails from their previous positions during the preceding 50 years. The rotation axis, i.e. geographic pole is marked by a black dot, the inner core tangent cylinder at the core-mantle boundary or projected to the Earth's surface by a white circle.
Br_gufm1_S.mpgVideo stream data5.8MBOkt 2007Animation: Radial magnetic field at the core-mantle boundary from the gufm1 model [Jackson et al., 2000] for the southern hemisphere with locations of magnetic (yellow star) and geomagnetic (green cross) poles at the Earth's surface. The pole marks have tails from their previous positions during the preceding 50 years. The rotation axis, i.e. geographic pole is marked by a black dot, the inner core tangent cylinder at the core-mantle boundary or projected to the Earth's surface by a white circle.
Br_CALS7K_N.mpgVideo stream data12MBOkt 2007Animation: Radial magnetic field at the core-mantle boundary from the CALS7K.2 model [Korte and Constable, 2005] for the southern hemisphere with locations of magnetic (yellow star) and geomagnetic (green cross) poles at the Earth's surface. The pole marks have tails from their previous positions during the preceding 500 years. The rotation axis, i.e. geographic pole is marked by a black dot, the inner core tangent cylinder at the core-mantle boundary or projected to the Earth's surface by a white circle.
Br_CALS7K_S.mpgVideo stream dataOkt 2007Animation: Radial magnetic field at the core-mantle boundary from the CALS7K.2 model [Korte and Constable, 2005] for the southern hemisphere with locations of magnetic (yellow star) and geomagnetic (green cross) poles at the Earth's surface. The pole marks have tails from their previous positions during the preceding 500 years. The rotation axis, i.e. geographic pole is marked by a black dot, the inner core tangent cylinder at the core-mantle boundary or projected to the Earth's surface by a white circle.

 

 

Contact

Profile photo of  Dr. Monika Korte

Dr. Monika Korte
Geomagnetism

Behlertstraße 3a
Building K 3, room 116
14467 Potsdam
tel. +49 331 288-1268