CALS7K is a main field model for the past 7000 years based on archeo- and paleomagnetic data. The spatial and temporal resolution is significantly lower than in models from current data, but it describes the general, large-scale evolution of the geomagnetic field over the past millennia, for example the dipole moment variation and secular variation at any location on Earth. Here we provide the model coefficients of the CALSxK family together with some fortran77 code to evaluate them. Several movies and snapshot plots can also be downloaded.

Our first continuous millennial scale model was CALS3K.1 for the past 3000 years and based only on directional (declination and inclination) data with a constraint on the axial dipole moment evolution to account for the lack of intensity information. The first model to include intensity data and thus providing an estimate of the dipole moment evolution was CALS3K.2, which immediately got outdated by CALS7K.1, the 7000 year version. CALS7K.1 has meanwhile been superseded by CALS7K.2. Those two models differ only for a southern hemisphere region in the first few millennia, where we corrected a weighting problem with a few data in CALS7K.2.

Note the limitations of the models due to the very uneven distribution of available data and data quality. Details are given in the following publications:

  • M. Korte, C.G. Constable, A. Genevey, U. Frank and E. Schnepp (2005): Continuous geomagnetic field models for the past 7 millennia: 1. A new global data compilation. Geochem., Geophys., Geosys. , 6(2), Q02H15, doi:10.1029/2004GC000800.

  • M. Korte 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.

  • M. Korte and C.G. Constable (2003): Continuous global geomagnetic field models for the past 3000 years. Phys. Earth Planet. Inter. , 140, 73-89.


FileTypeSizeDateContent ZIP150kBMay 2005CALS7K.2 Latest version for 5000 BC to 1950 AD. Model coefficients and fortran code to obtain model predictions for individual locations and times or time series and to obtain coefficients for individual epochs.
CALS7k2dipole.zipZIP30kBMay 2005CALS7K.2 Dipole moment predictions from CALS7K.2 from 5000 BC to 1950 AD with uncertainty estimates.
CALS7k2_1field2.pdfPDF6.4MBMay 2005CALS7K.2 Snapshot plots, centered on longitude 0
CALS7k2_1field2.pdfPDF6.5MBMay 2005CALS7K.2 Snapshot plots, centered on longitude 180
CALS7k1.zipZIP1.4MBMay 2005CALS7K.1 Model coefficients. Obsolete, for reference only. Can be used with software for CALS7K.2.
CALS3k2.zipZIP0.7MBMay 2005CALS3K.2 Model coefficients and fortran code, 1000 BC to 1950 AD. Obsolete, for reference only.
CALS3k1.zipZIP0.6MBMay 2005CALS3K.1 1000 BC to 1800 AD from directional data only. Model coefficients and code.


Profile photo of  Dr. Monika Korte

Dr. Monika Korte

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