Ionospheric Monitoring and Solar Flare/CME Detection

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 amplitude of the signal from an Australia VLF naval transmitter (Station NWC in Western Australia). VLF radio is especially senstitive to change in the ionosphere.
• The signal to noise ratio of GPS satellite transmission to a common GPS module.

VLF Monitor - Last 24 Hours

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.

GPS Data.

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.

S₄ Index

Traditional plot of S4 index for past three days.