30th URSI Convention on Radio Science, Sodankylä, Finland, 9-10 October 2006

A Woollen Aardvark in Sodankylä

Th.Ulich1 C. J. Rodger2, M. A. Clilverd3, T. Raita1, J. Manninen1

1Sodankylä Geophysical Observatory, Sodankylä, Finland,
2Dept. of Physics, University of Otago, Dunedin, New Zealand,
3British Antarctic Survey (NERC), Cambridge, U.K.


For some years, we are running a six-channel, narrow-band VLF receiver in collaboration with the British Antarctic Survey. The instrument was first deployed in Perunkajärvi, near Rovaniemi, and today it is situated at Pittiövaara Station near Sodankylä. The so-called OmniPAL (Omnifarious Phase and Amplitude Logger) system monitors typically six naval VLF transmitters in the northern hemisphere and allows to monitor the Earth-Ionosphere waveguide over large areas along the great-circle paths between transmitters and the receiver. There are several equivalent systems deployed around the world and collaborating through Aard(d)vark, i.e. the "Antarctic-Arctic Raditation Belt (Dynamic) Deposition - VLF Atmospheric Research Konsortia."

Since August 2005 however, Sodankylä has become a woollen aardvark! SGO has joined the World-Wide Lightning Location Network (WWLLN, pronounced "woollen") and a dedicated VLF receiver for real-time lightning detection has been installed at Pittiövaara. It monitors strong lightning at distances of greater than 500 km and relays the recorded VLF signatures in real-time to the central processing computer in Seattle, USA, where signatures from many receivers are combined and lightning locations are computed based on the time delays of the recordings. The entire network is synchronised by GPS timing. Every 10 minutes, maps of global lightning occurrence are published on the woollen web server at http://webflash.ess.washington.edu/.