Thunderstorm characteristics of cloud-to-ground lightning at the Kennedy Space Center, Florida: a study of lightning initiation signatures as indicated by Doppler radar

Abstract

A sum-nary of lightning characteristics was developed for the NASA Kennedy Space Center (KSC). From-n a 1989-1996 data set, the spatial patterns, temporal patterns, and first stroke mean peak current were analyzed. Forty five thunderstorms were chosen due to their isolated development over KSC. Forty of the storms representing summer (May through September) airmass thunderstorms and five storms representing winter were examined for their storms-n initiation characteristics. Radar reflectivity echoes at the -10 C,-15 C, and-20 C temperature heights were associated with cloud-to-ground (CG) lightning strike locations from the National Lightning Detection Network. A distinct region of high ground flash densities can be seen over land matching the topography of the KSC coastline. A maximum of values was observed during the summer months for both negative and positive flashes. The absolute i-magnitude of negative peak currents was found to be higher than positive peak currents in Florida. Although thunderstorms can Occur at any time during the day, the diurnal distribution of lightning flashes showed that the afternoon (2000-2200 UTC) was the time of maximum lightning activity. From a time history of radar-echoes, it was found that the 30 dBZ echo detected at the-I 5'C temperature height is the best indicator of the beginning of CG lightning activity. The observed median lag time between this lightning initiation signature and the beginning of CG lightning flashes was 15.5 minutes. Other lightning initiation signatures were also examined at all three temperature heights and did not yield as successful results.