Abstract
Some technical problems are described concerning the field measurements of the geomagnetic field by using SQUID magnetometer.
In the natural circumstances, the atmospheric temperature change, wind, rain and even the thunder activities bring several disturbances into the measurements of the geomagnetic field using SQUID. Among them, some of the troubles are attributed to the lower slew rate of the SQUID electronic circuits compared to that of the phenomena. Others come from the temperature effect of, also, the circuits, in particular, from the amplitude change of the RF oscillator due to the temperature change.
Several examples observed at Mt. ASO (lower magnetic noise site) are shown. A comparison of small geomagnetic changes at Mt. ASO with that at Syowa base, Antarctica, is made, and the coincidental events are found between the two sites separated more than 10, 000km.
