A Study of the Characteristics of Thunderstorm Cessation at the NASA Kennedy Space Center
AIR FORCE INST OF TECH WRIGHT-PATTERSON AFB OH
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A lightning summary was developed for a 100x100 kilometer area centered at the NASA Kennedy Space Center. Spatial and temporal patterns, and first stroke peak currents were analyzed from 1986-1995. Three thunderstorms were chosen due to their proximity to the Kennedy Space Center KSC and examined for their end of storm characteristics. Radar echoes at the -10 deg C and -20 deg C temperature heights were associated with cloud to ground CG lightning strike locations from the National Lightning Detection Network. Electric fields were also examined during the same time frame for any correlations. A pattern was observed for the spatial distribution of CG lightning. An inland maximum in ground flash density was observed during the summer months for both negative and positive flashes. The summer months had the lowest percentage positive flashes 2.5 while the maximum value occurred during the winter 11.4. Although thunderstorms can occur at any time during the day, the diurnal distribution of lightning flashes showed that the afternoon 2000 UTC was the time of maximum lightning activity. From a time history of radar echoes, it was found that a 45 dBZ echo, last detected at the -10 deg C temperature height, may be a good indicator of the end of lightning activity. The observed lag times between this lightning termination signature and the end of all CG lightning flashes was 30 min for all three thunderstorms.