An Object-Based Analysis of Lightning Characteristics in a Pre-Tropical Cyclogenesis Environment

June 12, 2025

Nick Mesa

Committee: Michael Bell (Advisor); Kristen Rasmussen; John van de Lindt (Civil and Environmental Engineering)

Abstract

This work utilizes the continuous, high-resolution data provided by the Geostationary Lightning Mapper (GLM) on GOES-16 to investigate lightning attributes in a pre-tropical cyclogenesis environment in the North Atlantic. An object-based framework providing additional spatiotemporal characteristics was used to evaluate the area and optical energy of binned GLM lightning groups through the Tracking and Object-Based Analysis of Clouds (tobac) Python package. Applying tobac's compositing and tracking methods to the GLM data was first tested with a rare case of genesis (Tropical Storm Claudette (2021)) within range of the NEXRAD network. The availability of ground-based, dual-polarization radar suggested that small area and low energy lightning was indicative of stronger convection and updrafts via composite vertical radar profiles of tobac lightning features. The physical interpretations of these lightning attributes were then applied to lightning 72 hours prior to genesis and within 200 km of the best-track invest center for four developing disturbances (Claudette (2021), Ida (2021), Earl (2022), and Beryl (2024)). The presence of small area and low energy lightning, previously associated with stronger updrafts and convection, was noted in all cases. There were also multiple instances where lightning attributes appeared to coincide with expected beneficial developments for genesis, particularly for Beryl. Questions remain regarding the impact of various factors, such as deep-layer vertical wind shear and background solar illumination, on GLM-measured lightning using this object-based framework. Overall, this work offers a novel characterization of oceanic lightning in a pre-tropical cyclogenesis environment for the North Atlantic basin.