VLF lightning location by time of group arrival (TOGA) at multiple sites

Lightning is located by using the time of group arrival (TOGA) of the VLF (3– 30 kHz ) radiation from a lightning stroke. The dispersed waveform (“sferic”) of the lightning impulse is processed at each receiving site. The TOGA is determined relative to GPS at each site from the progression of phase versus frequency using the whole wave train. Unlike current VLF methods which require transmission of the whole wave train from each site to a central processing site, the TOGA method requires transmission of a single number (the TOGA) for lightning location calculation. The stable propagation and low attenuation of VLF waves in the Earth–ionosphere waveguide (EIWG) allows a wide spacing of receiver sites of several thousand kilometer so that a truly global location service could be provided using only ∼10 receiver sites.