Lightning Activity in Atlantic Tropical Cyclones:Using the Long-Range Lightning Detection Network (LLDN)

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Sunday, 17 January 2010
Exhibit Hall B2 (GWCC)
Lumari Pardo-Rodriguez, UCAR/SOARS, Lajas, PR

Mitigating potential disasters from land-falling tropical cyclones requires accurate forecasts of trajectory and intensity. In the last 20 years, trajectory forecasting has improved 50%, while intensity forecasts have improved little or not at all. This lack of any major advances can be partly explained by poor understanding of the physical processes behind intensity changes. Few recent studies suggest that monitoring lightning activity in tropical cyclones could help improve understanding of these processes and also help predict intensification. We studied lightning in six Atlantic tropical cyclones using the Long-Range Lightning Detection Network, which reaches 2,000 kilometers offshore of the continental U.S. With exception of tropical cyclones intensifying close to continental landfall, lightning frequency didn't show a consistent peak before the time of maximum sustained winds. On the other hand, the outer rainband-to-eyewall lightning ratio shows a clear peak 24 hours before maximum sustained winds in all of the storms. A better understanding of the physics behind the temporal behavior of the ratio is needed. Preliminary assessment of these results suggests that some lightning changes could be related to the eyewall replacement cycle. Interaction of tropical cyclones with continents could increase lightning activity and the use of a ratio is not needed to see a clear peak in lightning before maximum sustained winds. A more detailed approach about the interactions between the outer rainband and eyewall lightning activity should be conducted. Lightning in the eyewall should be compared with radar and airplane observations to observe its relationship with the eyewall replacement cycles.