The geomagnetic dynamo is currently considered the most likely source of the Earth’s main dipole field. However, the radius of the current ring located in the Earth’s core is not reliably known. There are methods for indirectly estimating the radius of this current. Another method is proposed that allows one to indirectly estimate the radius of the current ring inside the Earth’s core based on measurements of the Earth’s magnetic field by observatories included in the INTERMAGNET network. The results of measurements taken on a day with low magnetic activity were compared using the least squares method with fields that could be created by ring currents of different diameters at the locations of magnetic observatories. The assumption was made that the ring current in the model used is located in the plane of the Earth’s equator with the center coinciding with the axis of rotation of the Earth. Estimates of the current radius in the range of 957–1595 km were obtained, which corresponds to the boundary between the solid and liquid cores of the Earth. These results can refine the model of the structure of the Earth’s core and Earth’s magnetism.

The integration of magnetic observatories of many countries into the Intermagnet network has provided researchers with new opportunities to investigate many geophysical processes. The joint processing of measurement evidence from magnetic observatories located in various geolocations makes it possible to better understand the dynamics of the interaction of solar plasma fluxes with the Earth's magnetosphere. For the correct interpretation of the dynamics of physical processes, the accuracy of the time reference of measurement results is of great importance. The measurement results of local observatories were transformed to a unified ecliptic coordinate system oriented towards the Sun in order to extract small variations in the magnetic field occurring before the magnetic storm commencement. Before transforming the coordinates, a constant component equal to the average daily value of the magnetic field components was removed from the results of minute-by-minute measurements. Owing to the averaging evidence from 84 magnetic observatories of the Intermagnet network, variations in the magnetic field of cosmic origin, preceding the magnetic storm commencement were detected. The correlation analysis of these variations recorded by different observatories revealed the presence of time shifts between the data series of different observatories. Only 62% of the observatories had a relative data shift within the range of ± 1 minute. Before the joint data processing in order to efficient use of data recorded with a time shift a method for correcting time shifts has proposed.