Very low frequency subionospheric communication transmitter observations (WWLLN)

The AARDDVARK/WWLLN Very Low Frequency (VLF) Radio Sensor was installed at Arrival Heights from 10-15 December 2008 by Dr Craig J. Rodger and Dr. James Brundell as part of Antarctica New Zealand Event K069a. The sensor measures the magnetic field in the Very Low Frequency radio range (~500 Hz-50 kHz), and passes it to a PC which processes the data for the experiments. The primary experiment is the AARDDVARK observations, which measures powerful and distant communications transmitters operating in the VLF range. As such, the dataset is "narrowband", taking amplitude and phase measurements at the transmission frequencies. For this sensor, there is 0.2s time resolution. The Konsortia sensors detect changes in ionisation levels from ~30-85 km altitude, with the goal of increasing the understanding of energy coupling between the Earth's atmosphere, Sun, and Space. We use the upper atmosphere as a gigantic energetic particle detector to observe and understand changing energy flows; this Science area impacts our knowledge of global change, communications, and navigation. 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, and thus said to be propagating "subionospherically". The sensor is currently logging transmitters in the northern & southern hemispheres, over a very wide longitude range. Both experiments send the processed data across the internet. AARDDVARK observations are sent to the University of Otago once a day at an agreed time. The new AH receiver is the 10th station in the AARDDVARK network, jointly lead by the University of Otago and the British Antarctic Survey.