The VLF antenna is designed to monitor the very low and extremely low frequency (VLF and ELF) portions of the electromagnetic spectrum. These frequencies include both naturally occurring and manmade signals. Natural sources include phenomena such as sferics (radio pulses from lightning), whistlers (signals that travel along magnetic field lines), chorus, and hiss—each of which provides insight into atmospheric and space weather processes.
Through the study of Very Low Frequency (VLF) waves we can gain insight into ionospheric conditions and the magnetic field structure. VLF monitoring can help detect disturbances caused by space weather events and their effect on the radiation belt.
The receivers at British Antarctic Survey’s Rothera and Halley research stations are part of a broader network of VLF monitoring stations distributed across the polar regions. Data collected from this network is shared with over 35 institutions worldwide, contributing to a wide range of scientific research.
The VLF antenna receives the VLF radio signals and then the signals are processed by various experiments.
The Worldwide Lightning Location Network (WWLLN – pronounced ‘woollen’) is a global, real-time network of lightning detection sensors operating in the very low frequency (VLF) range of the electromagnetic spectrum (3–30 kHz). It is managed by the University of Washington in Seattle.
WWLLN detects radio signals from lightning discharges, known as sferics, which dominate ground-based observations in this frequency band. Every second, the system identifies the five strongest lightning strokes and transmits their timing data to the central WWLLN server. Using data from multiple stations worldwide, the network triangulates the location of each lightning event.
The Ultra experiment, part of the AARDDVARK network, monitors VLF signals from global transmitters to study changes in ionisation levels between 30 km and 85 km altitude. Its main goal is to improve understanding of energy coupling between the Earth’s atmosphere, the Sun, and space.
The AWD is an experiment by Janos Lichtenberger, Eötvös University in Hungary. The AWD looks at the delayed lightning signal (whistlers) that travels down the magnetic field line to see how the signal changes due to ionospheric conditions.
A VLF Doppler experiment measures Doppler shifts and group delays in very low frequency (VLF) radio signals. The Doppler effect is the change in the frequency of a wave caused by the relative motion between the source and the observer.
The British Antarctic Survey also support 10 VLF sites outside of Antarctic in partnership with collaborators to add to the global coverage of VLF data. These sites run the Ultra experiment, and some sites additionally run the WWLLN or AWD experiments too.
| VLF site | Experiments | Longitude | Latitude |
| (geographical) | |||
| Ny Alesund, Norway | Ultra, WWLLN | 78.9252 | 11.9338 |
| Reykjavik, Iceland | Ultra, WWLLN | 64.1075 | -21.7917 |
| St Johns, NFL, Canada | Ultra, WWLLN | 47.5955 | -52.6781 |
| Ottawa, Canada | Ultra, UltraVELOX | 45.4070 | -75.5537 |
| Eskdalemuir, Scotland | Ultra, AWD | 55.3131 | -3.2055 |
| Seattle, USA | Ultra | 47.6541 | -122.3093 |
| Fairbanks, Alaska | Ultra | 64.8737 | -147.8605 |
| Ascension Island | Ultra | -7.9500 | -14.3782 |
| Sodankyla, Finland | Ultra | 67.4210 | 26.3897 |
| Kilpisjarvi, Finland | Ultra | 69.0711 | 20.7609 |
The objective of QEPPA is to work out the amount of charged particles that hit our atmosphere during space weather events in order to improve how our models represent this effect on our atmosphere and climate.
