Lightning from Two National Detection Networks Related to Vertically Integrated Liquid and Echo-Top Information from WSR-88D Radar

Abstract

Two national cloud-to-ground (CG) lightning-detection systems were operating across the contiguous United States during 1993. These two networks are compared to each other and to WSR-88D radar information collected by the Twin Lakes, Oklahoma, radar on 9 June 1993 as a squall line moved through central Oklahoma. Next Generation Weather Radar Information Dissemination Service data are used to investigate the relationship of CG lightning to WSR-88D echo tops and vertically integrated liquid (VIL). Such relationships appear not to have been investigated in such fine time and space resolution to date. When lightning is normalized by the frequency of occurrence of 4 km ? 4 km resolution echo-top areas, the greatest percentage of echoes with lightning occurs when echo-top heights exceed 50 000 ft (15.2 km). The percentage of echoes with lightning drops significantly as echo tops decrease. The relationship of VIL with lightning is not as clearly defined. The frequency of echoes with lightning increases gradually with 4 km ? 4 km resolution VIL values from 15 kg m?2 to about 40?45 kg m?2. Then a drop in the frequency occurs with higher values of VIL. However, a maximum in the frequency of echoes with lightning was observed at very high values of VIL (>65 kg m?2) by both lightning-detection systems. The Atmospheric Research Systems, Inc., (ARSI) time-of-arrival lightning detection system recorded nearly twice the number of positive flashes when compared with the GeoMet Data Services (GDS) direction-finder (DF) system. It appears that intraclound (IC) flashes contaminated the ARSI positive dataset to some extent. ARSI also recorded 24% fewer negative strokes probably due to communications saturation or signal attenuation.