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Research on lightning has been conducted on various topics including thunderstorm electrification and climatology of lightning strikes however; there are still some characteristics of lightning that are not well known, such as flash multiplicity and peak current as a function of individual thunderstorms. These characteristics are the leading cause of injuries and damage each year. This study examines a severe weather event in Minnesota on 16 September 2006, in order to determine what may cause peak current and flash multiplicity. Cycles in peak current and flash multiplicity are identified and then associated with CAPE to determine if a thunderstorm’s updraft controls these cycles.
Candidate thunderstorms are identified by hand based radar reflectivity and then tracked. These candidate thunderstorms are then associated with cloud-to-ground lightning strikes. Time series of cloud-to-ground lightning strikes for individual thunderstorms are created. These time series are then transformed into the frequency domain by using a FFT in order to determine if there is a cycle in lightning characteristics. The resulting periodicities are then correlated with CAPE and cycles in radar reflectivity of thunderstorms.
It was concluded that a coherent periodicity of lightning characteristics does not exist. The majority of cycles identified had no correlation to CAPE and those that did have a cycle are weakly correlated at best with CAPE. The most correlated parameter with lightning strike characteristics cycles are cycles in radar reflectivity. This result suggests that updraft cycling and pulsing may have an affect on multiplicity and peak current.
Adviser: Adam L. Houston