World-wide lightning location using VLF propagation in the Earth-ionosphere waveguide

Abstract

Worldwide lightning location (WWLL) using only 30 lightning sensors has been successfully achieved by using only VLF propagation in the Earth-ionosphere waveguide (EIWG). Ground propagation or mixed "sky" and ground propagation is avoided by requiring evidence of Earth-ionosphere waveguide dispersion. A further requirement is that the lightning strike must be inside the perimeter defined by the lightning sensor sites detecting the stroke. Under these conditions, the time and the location of the stroke can be determined, along with the rms errors. Lightning strokes with errors exceeding 30 Ps or To assist with identifying impulses from the same lightning stroke, the lightning sensor threshold is automatically adjusted to allow an average detection rate of three per second. This largely limits detection to the strongest 4% of all lightning strokes, of which about 40% meet the accuracy requirements for time and location.

Direct satellite observation of lightning-produced NO<sub>x</sub>

“…Figure A3 shows the resulting DE for 2005 and 2008 exemplarily. DE is highest over Australia and Indonesia, as WWLLN evolved from a regional network initiated in New Zealand (Dowden et al, 2008). Over the years, the number of participitating stations increased from 19 (2004) to 30 (2007) (Rodger et al, 2009), which improves the DE also for other parts of the world, in particular for central and northern America.…”

“…WWLLN started operation as global lightning location network in 2003 (Dowden et al, 2008). It consists of ≈20-30 sensors around the world detecting "sferics" caused by lightning in the very low frequency (VLF) band (6 to 22 kHz).…”

A source location algorithm of lightning detection networks in China

“…If the azimuths are dispersive, this corresponds to the situation that the source is inside or near the network, thus the retrieval error is small. This fact can be used to explain why the necessity of "surroundedness" for adequate accuracy applies to all lightning location networks that use timing alone for location (Dowden et al, 2008).…”

“…Hu (zhixianghust@gmail.com) the US National Lightning Detection Network (NLDN), the lightning detection network in Europe (LINET), Zeus in Europe and Africa, and the World Wide Lightning Location network (WWLLN) (Cummins et al, 1998a;Betz et al, 2009;Chronis and Anagnostou, 2006;Dowden et al, 2008;Rodger et al, 2005Rodger et al, , 2006, etc. These long-range lightning detection networks primarily locate cloud-to-ground (CG) lightning which is hazardous to human society.…”

“…Although the IMPACT algorithm is commercially successful, the specific software is proprietary and not widely distributed free of charge to the scientific community, and its data processing ability is constrained by computer power. In WWLLN, the lightning strokes are located using the "downhill simplex" method (Dowden et al, 2008;John and Mead, 1965), which is also a searching method similar to the IM-PACT algorithm.…”