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 Trial

Signals from GPS satellites are affected by disturbances in the ionosphere caused by space weather. In theory, the signal to noise ratio of each GPS satellite signal can be used to examine this:

• Noise - 1hr: A bubble plot of each visible GPS satellite, with the size of the bubble corresponding to instances of noise as the satellite moves overhead.
• GPS Noise - 24hr: The position of all noise events for the past 24 hours. Only noise readings above 40 deg in altitude are considered, in order to reduce false readings from low altitude glancing reflections (multimodal signals) and obstructions on the horizon like trees, roofs, etc.

GPS noise data is also sensitive to: physical objects that shadow the GPS sensor, low altitude of satellites (interferance by structures at the horizon, trees, etc.), and reflection off surfaces like roofs and walls.

Hourly Count GPS Noise Events

Rolling Count GPS Noise Events