Radar nowcasting of total lightning over the Kennedy Space Center

The NASA Kennedy Space Center (KSC) is situated along the east coast of central Florida, where a high frequency of lightning occurs each year and poses a hazard to the space center's operations on a daily basis. Although cloud-to-ground (CG) lightning initiation forecasting using radar echoes has been thoroughly analyzed, very few studies have examined intracloud (IC) and/or total (IC + CG) lightning. While CG lightning may be of most importance to ground operations, IC lightning is also of great concern to the Kennedy Space Center launch operations.

In addition, nearly all past radar-based lightning forecasting studies have been limited in the number of convective cells analyzed, relying mainly on a case-by-case investigation of storms. The need exists for further study of larger sample sizes of cells, so as to arrive at statistically significant conclusions regarding the best lightning forecast criteria.

In this study, four years (2006-2009) of summer (June, July, August) daytime (about 14-00 Z) Weather Surveillance Radar – 1988 Doppler data for Melbourne, FL were analyzed. Convective cells were tracked using a modified version of the Storm Cell Identification and Tracking (SCIT) algorithm and then correlated to CG lightning data from the National Lightning Detection Network (NLDN). Additionally, total lightning data acquired from the KSC Lightning Detection and Ranging (LDAR) networks I and II were correlated to tracked convective cells; VHF sources from the LDAR networks were group into flashes prior to correlation.

Pairs of reflectivity values (30, 35, and 40 dBZ) at isothermal levels (-10, -15, -20 and updraft -10°C) as well as a vertically integrated ice (VII) product were used to optimize criteria for radar-based forecasting of both IC and CG lightning within storms. The value of IC flash detection as a precursor to CG occurrence was also analyzed. Finally, the enhancement of the KSC LDAR II network over the LDAR I network, specifically in regard to forecast verification, was investigated.