Lightning phenomenology in the Tampa Bay area

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Abstract
A lightning locating system employing two wideband, gated magnetic direction finders was used to study the negative cloud‐to‐ground lightning in 111 storms that occurred on 8 days during August 1979 in the Tampa Bay area of Florida. The storms were classified as (1) single‐peak storms—spatially isolated groupings of lightning whose cloud‐to‐ground flashing rate vs. time curves exhibited a single peak; (2) multiple‐peak storms—spatially isolated groupings of lightning with multiple‐peak flashing rates; and (3) storm systems—two or more related single‐peak and/or multiple‐peak storms. The following parameters are given for single‐peak storms, multiple‐peak storms, and storm systems: duration, area, number of ground flashes, mean ground flash density, mean ground flashing rate, and maximum ground flashing rate averaged over a 5‐min interval. Ground flash counts are corrected for the location system detection efficiency, which varied from about 75% at close range to about 55% at 100 to 150 km. The mean duration of single‐peak storms, multiple‐peak storms, and storm systems was 41, 77, and 130 min, respectively; the mean area 103, 256, and 900 km2, respectively; and the mean number of lightning flashes to ground 73, 270, and 887, respectively. The mean ground flash density for single‐peak storms, multiple‐peak storms, and storm systems was 18×10−3, 15×10−3, and 9.7×10−3 km−2 min−1, respectively; and the mean ground flashing rate 1.7, 3.4, and 6.8 min−1, respectively. The highest maximum ground flashing rate averaged over a 5‐min interval for all single‐peak storms, multiple‐peak storms, and storm systems was 17, 22, and 32 min−1, respectively, while the mean of the maximum flashing rates was 3.7, 7.3, and 14 min−1, respectively. The relation between storm duration D in minutes and number of ground flashes Ng for single‐ and multiple‐peak storms can be described by log10 Ng = 0.014D + 1.2.

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