The plot below shows the magnetic field strength variations as recorded by Stuart Green in Preston, Lancashire, UK. Stuart explains how the measurements are made: ‘My magnetometer is based on an FGM3 fluxgate sensor buried in my garden in protective packaging, pointing in an east-west orientation to measure the local magnetic field variations in this direction. This is to minimise temperature fluctuations as the sensor is highly sensitive to changes in its thermal environment. The output is a train of pulses, the frequency of which is dependent on the strength of the local magnetic field. These are ultrasonic and need down converting using an electronic circuit to within the operating frequency range of my computer’s sound card. The signal is recorded using Spectrum Lab free software and sampled every 2.5 minutes to my hard drive. This system is highly sensitive and provides a detailed record of my local geomagnetic environment as it changes as a result of space weather 24/7’. Further details can be found here.
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