HISTMAG

A study on medieval churches
from Lower Austria and northern Germany revealed that their axes were not oriented in eastern direction by
means of the compass. Further records providing information on the geomagnetic field far beyond the historical
epoch can be gained from archeo- and paleomagnetic (indirect) measurements. Archeomagnetic campaigns were
conducted, which contributed to the extension of the data collection or were used for archeomagnetic purposes.
The newly acquired direct and indirect records as well as already published collections were compiled in the
online-database
HISTMAG,
which formed the basis for detailed evaluation of the different datasets. Systematic deviations between indirect
and direct records were investigated in combination with newly developed methods for the handling of these
extremely inhomogeneous datasets. A “user-comment-function” within HISTMAG database allows for a
scientific discussion and, therfore – beside the available meta information –,
for an additional quality
assessment of single records.
The existing modelling approach was adopted based on the database and studies on data quality. Unreliable
records were filtered and the heterogeneous data distribution, which is characterized by a strong increase in
number within the historical epoch, was homogenized. The final model allows for field predictions at any
location on the Earth's surface with corresponding uncertainties for the last 3000 years. Additionally, studies on
the field behavior at the core-mantle-boundary as well as on field features (e.g., so-called jerks) can be
performed.
Beside general statements on the temporal and spatial evolution of the geomagnetic field, the model can be used
for archeomagnetic dating purposes as already demonstrated for an archeological study. A further application
example is given by the possible connection of strong field and climatic variations.