WWLL
World Wide Lightning Location Network
SYSTEM MESSAGE: Note: THIS is not the main WWLLN webpage. Please reset your browser to http://webflash.ess.washington.edu. This present web page (on flash4) is a backup, and is not maintained in the most recent condition to reflect the WWLLN adequately. RHH

LF*EM of New Zealand, partnering with the University of Washington in Seattle, is operating a network of lightning location sensors at VLF (3-30 kHz). Most ground-based observations in the VLF band are dominated by impulsive signals from lightning discharges called “sferics”. Significant radiated electromagnetic power exists from a few hertz to several hundred megahertz, with the bulk of the energy radiated at VLF.

With our network of sferic sensors we are producing regular maps of lightning activity over the entire Earth. Our map showing the entire world uses coloured spots to indicate lightning strokes (red stars inside an open circle are active WWLL ightning sensor locations).  Click on the map to expand.

We welcome offers of hosting a new WWLL sensor to add to the list above. All hosts receive all the world-wide data for their own research on monthly CDs. In return, each host provides the computer and meets any local expenses like power, Internet, and maintenance.  However, do not think that a sensor on your own campus is going to give you lightning location data on its own. Only the whole network does that.

Each lightning stroke location requires the time of group arrival (TOGA) from a least 4 WWLL sensors. These sensors may be several thousand km distant from the stroke. In fact, there is some evidence to suggest that the sensors close to the lightning stroke are unhelpful. The geographical  arrangement  of the sensors is important: a lightning stroke which is enclosed by sensors is much more accurately located than one which is not so enclosed. Clearly a uniform spacing of sensors around the Earth is the ideal. Since the Earth is round, there are no edges: every lightning stroke is surrounded by sensors, but not necessarily by the sensors which sense it. Currently (2004) only about 50% of strokes detected  by one sensor are detected by 4 or more. These strokes are presumably the stronger ones.

To cover the whole world by sensors spaced uniformly about 1000 km apart would require roughly 500 sensors. If spaced 3000 km apart, we would need “only” around 50 sensors. We already have about half this number: mainly in developed countries but not enough in less-developed countries, many of which are in the tropics where lightning is most prevalent.

So if you are interested in hosting, have a look at the current WWLL station locations (white circles with a red asterisk inside) on the World map linked above to see where new WWLL stations would be useful. Note that every WWLL station needs a dedicated computer (linux box) permanently connected to the Internet for continuous transmission of data to the central processing computers which make the lightning strike locations.

Direct Weather comparison

WWLL map with superimposed cloud viewed by satellite (updated periodically)
(also see other views Americas or Europe/Africa )
(Thanks to National Weather Service/Aviation Weather Center for images of cloud cover).

More information