Remote sensing space weather events through ionospheric radio: The AARDDVARK network

The joint NZ-UK Antarctic-Arctic Radiation-belt (Dynamic) Deposition - VLF Atmospheric Research Konsortia (AARDDVARK) is a new extension of a well-establish experimental technique, allowing long-range probing of ionisation changes at comparatively low altitudes. One of the few experimental techniques that can probe these altitudes uses very low-frequency (VLF) electromagnetic radiation, trapped between the lower ionosphere (_85 km) and the Earth; these signals can be received thousands of kilometres from the source. The nature of the received radio waves is determined by propagation inside the Earth-ionosphere waveguide, with variability largely coming from changes in the electron density profiles at and below the lower ionosphere. Most other instruments which can probe the same altitudes are limited to essentially overhead measurements. We have recently developed the AARDDVARK global-scale network of sensors that monitor fixed-frequency communications transmitters, and hence provide continuous long-range observations between the transmitter and receiver locations. Our receivers log small changes in the phase and amplitude of powerful VLF communications transmitters (13-30 kHz). By monitoring distant VLF stations we undertake long-range remote sensing of changes to the waveguide, and particularly the ionosphere. This Science area impacts our knowledge of space weather processes, global atmospheric change, communications, and navigation. AARDDVARK measurements are well suited for comparison with spacecraft measurements, to provide continuous measurements of radiation belt precipitation while satellites observe dynamic changes, particularly near the geomagnetic equator. Future additions to the network will increase the science potential and provide global coverage of space weather event signatures. In 2010 a new AARDDVARK station was deployed near Edmonton, Canada. This was followed by two new "deep field" sites in the Antarctic in 2012 as well as two more Canadian r- ceivers, all to support the planned fleet of radiation belt science platforms (RBSP, DSX, RESONANCE, ERG, etc). This poster will provide updates on the AARDDVARK network of receivers, as well as some recent AARDDVARK-science.