Long Term Variation of Geomagnetic Curvature Recorded by Absolute Measurement in Different INTERMAGNET Observatories (Comprehensive Study)

The main task of the present day geomagnetic observatories is to record the elements of the geomagnetic field. This task is performed if the intensity and the direction of the geomagnetic field became known on one point. Standard observatory instrumentation gives further chances to measure the magnetic gradients and identify several changes of the magnetic gradient. These methods were tested before. In this paper we present the comprehensive study of three INTERMAGNET observatory’s long term dataset. In the focus of our data processing is the variation of a special magnetic gradient which is always observed during routine absolute magnetic measurements. As a cosequence we will study only the inclination readings of the complete set of absolute measurement. The difference between the two absolute values of inclination records will represents the curvature of the geomagnetic field measured in the magnetic meridian plane.

Long term high quality observatory dataset can provide a good basement to study the fluctuations when the observation is far away from strong conductivity anomalies.

It will be shown that we can find quiet periods when the studied difference shows high stability. On the other hand the disturbed periods also appear in every observatories.