Tropical cyclone lightning characteristics as revealed by the World Wide Lightning Location Network (WWLLN)

Lightning occurrences within tropical cyclones have been used to infer not only aspects of the electrical nature of these storms, but also some of their dynamical and microphysical characteristics. There have also been efforts to link tropical cyclone lightning activity with intensification and cyclogenesis. Given the relatively rare and episodic nature of lightning, robust conclusions can only be found in samples spanning several tropical cyclones, yet most studies have been limited to a few storms because of the challenges that lightning detection over the open ocean presents.

The World Wide Lightning Location Network (WWLLN) is a ground-based network that locates flashes across the globe, including the tropical oceans. We show an increasing detection efficiency of the WWLLN since its inception, currently reaching values above 10%. We also show that this, still low percentage, holds a strong statistical proportionality with the National Lightning Detection Network in the 24 tropical cyclones that came within 400 km of the United States coastline between 2004 and 2007. An extensive inter-network comparison details the high reliability of the WWLLN in tropical cyclone research.

With this confidence in the WWLLN's detection abilities, we study the lightning flashes of the 74 tropical cyclones that occurred in the Atlantic Basin from 2004 to 2007 and the 99 tropical cyclones that occurred in the eastern North Pacific between 2004 and 2009. We compare and contrast the radial and azimuthal distribution of flashes in the two basins and explore the implications to the dynamical and microphysical aspects of tropical cyclones, with particular emphasis on the intensification process.