Date of Award
2018
Document Type
Dissertation
Degree Name
Doctor of Philosophy (PhD)
Department
Atmospheric Science
Committee Chair
Lawrence D. Carey
Committee Member
Phillip Bitzer
Committee Member
Kevin Knupp
Committee Member
Sundar Christopher
Committee Member
Timothy Lang
Subject(s)
Lightning, Convection (Meteorology)--Mathematical models, Radar
Abstract
Cloud electrification leads to the production of nitrogen oxides (NOx), which have an effect on ozone concentrations. Currently uncertainties exist regarding the contribution of lightning to the global and local NOx budget. Most lightning NOx (LNOx) models distribute the LNOx at reflectivities ≥20 dBZ, while vertically, a Gaussian distribution function with a peak at 7–8 km above mean sea level (MSL, -15°C) is used for parameterized cloud-to-ground (CG) flashes and a bimodal distribution function with peaks at 7–8 km (-15°C) and 11–12 km MSL (-45°C) is used for parameterized inter-/intra-cloud (IC) flashes. This research therefore aims to improve our basic understanding of lightning location relative to radar reflectivity and altitude as a function of storm and flash type. While the majority of research only differentiates between IC and CG flashes, there exists a third flash type, known as hybrid (HY) flashes, which are classified as CG flashes in most prior flash type studies. In an effort to show that IC, CG and HY flashes should be separately classified, the two-sample Kolmogorov-Smirnov (KS) test was applied to the flash sizes, flash initiation and flash propagation altitudes for IC, CG and HY flashes. The KS test statistically showed that IC, CG and HY flashes do not have the same parent distributions and thus should be separately classified. Further, two dimensional (2D) histogram distributions relative to reflectivity and altitude were created as a function of both storm type (i.e., multicells, mesoscale convective systems [MCSs] and supercells) and flash type (i.e., IC, CG and HY flashes). These 2D histogram distributions showed that although CG flashes initiate and propagate at the same altitude irrespective of storm type, IC flashes could have differences of up to 2km (10°C), while for HY flashes these differences increased to up to 3 km (20°C) relative to storm type. HY flashes are also consistently larger than IC and CG flashes, and flashes that originate in MCSs have larger overall sizes as compared to multicells and supercells. Thus, separating between storm type and flash type is important if one aims to improve where LNOx is distributed in models.
Recommended Citation
Mecikalski, Retha Matthee, "Improved understanding of lightning characteristics relative to radar and altitude profiles" (2018). Dissertations. 146.
https://louis.uah.edu/uah-dissertations/146