Associate Professor Craig Rodger from the Space Physics group at the University of Otago describes his involvement in the setting up and running of the World Wide Lightning Location Network (WWLLN). Based on the production of a radio pulse produced by the lightning discharge, data collected from the network is analysed to accurately pinpoint the location of the lightning discharge.
The WWLLN is the World Wide Lightning Location Network, which we call ‘woollen’, and the reason we call it ‘woollen’ is because the whole technology behind WWLLN was invented in New Zealand. And one of the PhD students from America that we were working with thought it was cute, frankly, to come up with an acronym associated with New Zealand – the home of so many sheep – and being New Zealanders, we thought it was pretty neat actually.
It’s a good acronym because it’s got ‘worldwide’ in it, and the whole point of the WWLLN network is to provide worldwide lightning locations in almost real time. So the lightning discharge sends out a radio pulse out into the atmosphere. You can then pick up that radio discharge, the sferic. So working with a bunch of friends across the world, we’ve set up radio receivers all around the world – we’ve got about 60 at the moment. Each one of these radio receivers is like a vertical wire plugged into a computer that does some clever things, and it’s plugged into the internet.
So the radio sferic arrives at the radio receiver, and the computer goes ‘Oh, I just saw a lightning flash, I know the time’, and it sends across the internet the time of the radio pulse’s arrival at that station. It sends it to the University of Otago in Dunedin, New Zealand, and the University of Washington in Seattle, United States. And there we’ve got the processor computers.
When we combine the timing from multiple locations, we can work out where the lightning flash must have started from. After a lightning discharge, it takes us about 5 seconds to work out where that was and when that was on the world.
Associate Professor Craig Rodger, University of Otago, Department of Physics