An experimental VLF WorldWide Lightning Location (WWLL) network is beingdeveloped to provide realtime locations of cloud to ground lightning discharges occurringthroughout the globe. This network has expanded from a limited number of stations in theWestern Pacific to its current state of 11 stations, in most longitude sectors, with additionalstations planned in the near future. As part of the initial testing phase of the WWLL thenetwork has operated in a simple mode, sending the station trigger times into a centralprocessing point rather than using the sferic Time of Group Arrival (TOGA). During thisinitial stage, a significant quantity of lightning location data has been collected, some ofwhich is being applied to research questions. In this paper the operation of the WWLLnetwork is described, and the location accuracy of the pre-TOGA WWLL network ischaracterised. This is performed by contrasting commercial lightning location data from anAustralian network, Kattron, over 2 days in January 2002, with 4 WWLL stations coveringthe same region. It was found that there were 426 matched lightning events, corresponding tolightning discharges with large lightning return stroke peak currents (mean absolute peakcurrent of ~26kA compared with ~12kA for all Kattron events). By considering the randomerrors in the difference locations between the matching lightning events, an appropriateGaussian timing error for the WWLL network of receiving stations is determined, and hencean estimate for the global location errors for the existing 11-station network is found. The"worst-case" global location error for the existing network ranges spatially from 7.5–100km,with the global median being 15km, and the global mean 30km. When the TOGA method isimplemented, the station timing errors will decrease, allowing for an increase in the locationaccuracies. Hence, the location accuracy estimates determined in this paper will be veryconservative for the future WWLL network employing the TOGA technique.Key words. Meteorology and atmospheric dynamics (lightning,atmospheric electricity, instruments and techniques)
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