The ionosphere is high outer layer of the Earth's atmosphere, charged (ionised) by solar radiation. This charging allows radio signals to bounce off the ionosphere and propagate over long distance. The ionosphere is also sensitive to the impact of space weather, and when this happens we should see changes in the signal strength of radio transmissions. There are also signature markers for solar flare x-ray events, which are usually correlated with coronal mass ejections (CMEs).
At Dunedin Aurora we monitor:
The VLF antenna is a wire loop with approx 50 turns of wire. The signal is passed through a "SuperSID" filter and processed with Spectrum Lab software and custom software. Reception of long distance stations shows a diurnal variation in signal strength. This signal can be altered by space weather and x-rays generated by solar flares.
Signals from GPS satellites are affected by disturbances in the ionosphere caused by space weather. SIgnal to noise data from each satellite is converted into a unitless measure of ionospheric tubulence called the S4 Index. We overlay the last ten days of data to look for patterns in the data that co-incide with geomagnetic storms.
Traditional plot of S4 index for past three days.