Using Lightning Data to Unravel Tropical Cyclone Structure and Intensity Changes

Many recent studies have observed a connection between tropical cyclone (TC) intensity and enhanced lightning activity in both the inner core (0-100 km radius) and outer rainband (100-300 km radius) regions. While some studies show that a TC weakens following a burst of lightning, others have shown cases where the TC intensifies. The placement of the lightning burst with respect to the radius of the maximum wind may be an important determining factor of whether a TC weakens or intensifies following a burst. Determining how a lightning burst can signal future changes in TC intensity would be a valuable asset for operational forecasters since lightning detection, by networks such as the World Wide Lightning Location Network (WWLLN), is one of the only continuous monitoring tools for TCs located over the open oceans.

As the WWLLN has continued to add sensors around the globe, the detection efficiency of the network has increased, and it has become useful for tropical cyclone observations and research. A set of Atlantic and East Pacific TCs from 2005-2013 will be examined to determine if lightning bursts aid in intensification and if there is a common diurnal lightning signal in TCs. A case study of Hurricane Earl (2010), a TC that spent most of its life over the open Atlantic and distant from land, will be analyzed as a case study. The WWLLN identified a burst of lightning in the inner core of Earl that aided in the understanding of the TC dynamics that supported the subsequent rapid intensification of Earl into a major hurricane. Additionally, a diurnal signal in the lightning was observed that propagated radially outward each day, supporting the findings of a recent study that suggested the diurnal cycle in TCs is relevant to structure and intensity changes.