Dunsink Lane, Dublin 15, D15 XR2R dunsink@dias.ie

SuperSID: Monitoring Solar Activity and Ionospheric Disturbances

The Sun is an active star that can produce solar flares and solar storms. Sometimes, these events can cause effects on the Earth’s magnetic field and upper atmosphere – the ionosphere. These space weather events are important to monitor as they can damage satellites, disrupt power grids and electrical systems, and interfere with communications systems. At Dunsink, we are monitoring the ionosphere and the impacts of solar flares on it using a SuperSID receiver.

The figures below shows live data from our SuperSID receiver in Dunsink. The top plot depicts a measurement of the strength of the signal received from the selected very low frequency (VLF) transmitter. Spikes in the signal strength indicate some ionsopheric disturbance. The bottom plot is a measurement of the Sun’s X-ray flux as measured by two GOES spacecraft.┬áThis data is useful for us to verify that an increase in signal strength is a solar flare and not caused by some other interference.



Near-realtime monitoring of the ionosphere from the Dunsink SuperSID. Additional data can be obtained from our VLF archive.

The ionosphere is the ionised layer of the Earth's upper atmosphere that stretches from 50 km to nearly 1,000 km above the Earth's surface. It is known to react strongly to the X-rays and ultraviolet radiation released by the Sun. This impact is known as a sudden ionospheric disturbance (SID).

The ionosphere may be monitored by bouncing VLF radio waves off of it. But where do these VLF waves come from? Several nations have transmitters located around the world, they use VLF waves to communicate with their submarines because these wavelengths can penetrate water. We monitor the ionosphere using a SuperSID receiver that is tuned to a number of VLF transmitters in Europe, the US and as far away as Japan. We currently receive VLF radio waves from five transmitters across the globe - check out the locations of these transmitters in the map below!

The Solar Physics and Space Weather Research Group uses SuperSID to monitor the impact on the Earth's ionosphere of solar flares, intense eruptions of electromagnetic radiation from the Sun. The table below shows how the X-ray flux of flares are classed, with B being the most common and weakest solar flare class, while X is the rarest and strongest. Each class has 9 subdivisions ranging from 1 - 9, e.g. M5 or X2. These subdivisions are indicated by the multiplier attached to the intensity. i.e. M5 = 5x10-5 Watts per square metre.

Solar Flare ClassIntensity [Wm-2]
  B  I < 10-6
  C  10-6 <= I < 10-5
  M  10-5 <= I < 10-4
  X  10-4 <= I < 10-3

DIAS operate two SuperSIDs, one at DIAS Dunsink Observatory near Dublin and the other at the Rosse Observatory in Birr Castle Demesne in the Irish Midlands.

Our SuperSID data are available from the DIAS VLF archive. Please credit DIAS Dunsink Observatory and SuperSID when using these data. SuperSID was developed by the Stanford University Solar Center and the Society of Amateur Radio Astronomers.