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 also have 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 are limited to 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, reaching overall values above 10%. We also show that this, still low percentage, holds statistical proportionality with the National Lightning Detection Network (NLDN), another ground-based network with high detection efficiency within the continental United States and adjacent oceans.

We study the lightning flashes of the 74 tropical cyclones that occurred in the Atlantic Basin from 2004 to 2007 using the WWLLN, and separately examine the 24 tropical cyclones that reached the United States coastline with the WWLLN and NLDN. The internetwork comparison details the high reliability of the WWLLN in tropical cyclone research. With this result in hand, we examine the radial and azimuthal distribution of flashes in tropical cyclones and explore the implications to the dynamical and microphysical aspects of tropical cyclones, with particular emphasis on the intensification process.