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Geomagnetism Geomagnetometry is the study of the Earth's magnetic field and how it interacts with the local surroundings and includes the study of worldwide geomagnetic disturbances (geomagnetic storms) caused by the solar wind and disturbances caused by natural events such as earthquakes and possibly volcanic activity nearby. A geomagnetometer, or just magnetometer, is an instrument used to measure Earth's magnetic field. Click here for real time magnetometer data from our Anchorage observatory. Click here for a description of the Simple Aurora Monitor (SAM) used in our observatory and click here for a tutorial on geomagnetism. We occasionally write reports of geomagnetic activity in which we compare our own observations with observations from the GOES (Geostationary Operational Environmental Satellites), Alaska Magnetometer Chain and other observatories. These reports may be downloaded by clicking here. We originally used a three phase approach in our study of geomagnetism, as described below. We presently are in Phase III. Phase III - Installation of 3-axis SAM-III. This phase was completed in October 2010 and is the system presently used to gather 3-axis data for our geomagnetic studies. The Phase III installation is described here. We commissioned Phase III on 11 October 2010 based on the 3-Axis Simple Aurora Monitor (SAM-III). Click here for real time geomagnetometer data from the SAM-III system in our Anchorage observatory. Phase II - Advanced experimental and monitoring phase to build a more advanced geomagnetometer system also based on the FGM-3 or FGM-3h. The Phase II experimental setup is used to study the feasibility of correlating local magnetic field measurements with very low frequency (VLF) electric field measurements and solar events. We commissioned Phase II on May 27, 2009 based on the Simple Aurora Monitor (SAM) and replaced it on 11 October 2011 with the SAM-III. The Phase II installation was completed May 26, 2009 with the Simple Aurora Monitor (SAM) signal processor and FGM-3 sensor. The sensor is buried approximately 50 cm below ground level to prevent diurnal temperature variations from affecting the sensor. The sensor cable is 2-pair, 22 AWG shielded buried service cable approximately 40 m long. Phase I - Basic experimental phase to build a relatively simple magnetometer system based on the Speake & Co Llanfapley FGM-3 or FGM-3h magnetic sensor and their SLC-006B application specific integrated circuit (ASIC). Click here for detailed information on the FGM-3 and FGM-3h sensors used in our applications. The Phase I experimental setup is used to determine the local magnetic field environment through calibration of the sensor using a known field. The known magnetic field is generated by a long coil of known dimensions and wire turns carrying a known current. The sensor is inserted in the coil and measurements made for various orientations. These are then compared to measurements made with the sensor in its field environment. Sensor characterization studies are not yet completed. |
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