Investigating Possible Causative Mechanisms Behind the Houston Cloud-to-Ground Lightning Anomaly
Abstract
Anthropogenic influences such as the Urban Heat Island (UHI) and increased aerosol concentrations have been postulated for many years to have an effect on lower tropospheric chemistry, convection, lightning and rainfall. Moreover, these influences have been invoked as possible explanations for the cloud-to-ground (CG) lightning anomalies observed over the Houston metropolitan area. In particular, Orville et al. (2001) and Steiger et al. (2002) reported a 45% increase in annual CG lightning flash densities over and downwind of the Houston urban corridor relative to rural surroundings citing anthropogenic influences as possible causative mechanisms. Extending these findings, Gauthier et al. (2005) demonstrated that in a regional context the Houston CG lightning anomaly is a non-unique feature, embedded within the larger-scale enhancement of CG lightning along the Texas and Louisiana Gulf Coast. Despite the fact that the Houston area is located at the western edge of this coastal enhancement, Gauthier et al. found this anomaly to be a persistent summer-season feature (even when large lightning events were excluded from the analysis) with flash densities over and downwind of the Houston metropolitan area on the order of 1.5-2 times that of its immediate surroundings. Interestingly, these particular types of urban signals in CG lightning activity have also been noted downwind of other cities in the U.S. and abroad. Although neither new, nor individually unique to the Houston area, the primary hypotheses offered to explain the localized enhancement in summer-season CG lightning revolve around "urban" effects.
Document Details
- Document Type
- Technical Report
- Publication Date
- Nov 22, 2005
- Accession Number
- ADA441226
Entities
People
- Michael L. Gauthier
- Walter A. Petersen
Organizations
- University of Alabama in Huntsville