Anthropogenic Structures and Cloud-to-Ground Lightning Location: 1992-2015

For over 80 years of scientific inquiry, tall structures have served as a mechanism to study characteristics of lightning. Most of these studies have been constrained to a single tall structure or fixed area of tall structures. Over the past two decades in the United States, over 100,000 new antenna towers were added to populated regions to keep up with the expansion of the national telecommunications network. Over this same period, the continued development of and improvements to the National Lightning Detection Network (NLDN) provide the ability to resolve cloud-to-ground (CG) strike locations with less than 1km spatial error. Since the inception of NLDN, numerous gridded climatologies have established the relationships between lightning frequency, time, and location. However, many of these climatologies were performed at coarse spatial resolutions (>20km) and subsequently mask out any evidence of and ability to quantify observational lightning preference to taller structures.  This study quantifies the attraction of lightning to man-made towers and explores the likelihood of the influence of these towers on the production and location of CG lightning over time.

In the first part of this study, we provide a high-resolution 23-year gridded (0.01°x0.01°) climatology of CG lightning in the United States. Over this period, 295,320,900 CG strikes occur within the continental United States. Within a gridded climatology, there are 136 gridded pixels with over four times the CG strike frequency compared to its surrounding areas. In all 136 cases, a communications tower registered with the Federal Communications Commission (FCC) ranging from 103m to 609m in height above ground level exists within 1km of the pixel centroid. Normalizing CG strike area and comparing the CG strike density at 0-1km and 1-2km away from an isolated FCC-registered tower, over 95% of towers analyzed had a higher CG density in the 0-1km region over the 1-2km range ring. In over 30% of cases, the 0-1km lightning density is double what is observed at the 1-2km range.