Geomagnetic change for the last 7000 years
Change in the geomagnetic field for the long time is called Geomagnetic Secular Variations. Many researchers investigate them since it is thought that they represent the characteristics of the geodynamo process working in the outer core. The data of the magnetci field observed by human beings are not enough to investigate the geomagnetic secular variation, since we has monitored the geomagnetic field only for the several hundred years. Instead researchers have been gathered fossils of the past field with using methods of paleomagnetism.
Here we introduce a geomagnetic secular variation model during the last 7000 years, which was constructed from paleomagentic dataset of archeological samples (potteries and kilns) and sediments on the floor of oceans and lakes. This mode named "CALS7K.2" (Korte and Constable, 2005) was analysed by the group in UCSD.
Snapshot, click to zoom up:
LEFT: Magnetic field lines and contour map of radial component (Br)
RIGHT: Flip-over image of magnetic field lines, for 3D stereograhic view.
KML files:
- Magnetic field lines: CALS7K2_MFL_20120308.kmz (57MB) HEAVY!
*modified for latest versions of Google Earth (2012/03/08) - Northward comp. Bx[nT]: CALS7K2-Bx_20081227.kmz (4.0MB)
- Eastward comp. By[nT]: CALS7K2-By_20081227.kmz (3.2MB)
- Downward comp. Bz[nT]: CALS7K2-Bz_20081227.kmz (6.4MB)
- Field intensity F[nT]: CALS7K2-Int_20081227.kmz (4.4MB)
- Declination D[deg]: CALS7K2-Dec_20081227.kmz (7.0MB)
- Inclination I[deg]: CALS7K2-Inc_20081227.kmz (5.1MB)
- Radial comp. Br[nT]: CALS7K2-Br_20081227.kmz (6.4MB)
Reference:
Korte M. and C. G. Constable,
Continuous geomagnetic field models for the past 7 millennia: 2. CALS7K.,
Geochem., Geophys., Geosys.,
Geomag. past 400yr << Geomagnetic change during last 7000y >> Geomag. during reversal