Wednesday, 15 May 2002: 11:15 AM
Lightning detection and ranging (LDAR II): results from Global Atmospherics, Inc. Dallas-Fort Worth research network
Global Atmospherics, Inc. (GAI) recently installed a regional Lightning Detection and Ranging (LDAR II) network for research purposes in the vicinity of Dallas-Fort Worth (DFW) International Airport. This network became fully operational on 1 March 2001. The DFW LDAR-II network is made up of 7 sensors, with 20 to 30 km baselines, that can detect pulses of radiation produced by the electrical breakdown processes of lightning in a 5-MHz band within a subset of the VHF (50-120 MHz) band. This regional LDAR-II network can map lightning flashes in 3-dimensions within approximately 150 km of the center of the network, degrading in performance with increasing range. Expected lightning flash detection efficiency is greater than 99% within the interior of the DFW LDAR-II network (a range of 30 km from DFW International Airport) and greater than 90% out to a range of 150 km from DFW International Airport. Three-dimensional location accuracy for individual pulses of radiation is better than 100 m within the interior of the network and better than 2 km to a range of 150 km from the network center.
Early analysis of the DFW LDAR-II network involved comparisons of LDAR II data with the U.S. National Lightning Detection Network (NLDN) and radar base reflectivity images from the DFW National Weather Service (NWS) radar. The results of these comparisons will be summarized for representative thunderstorm cases. Recently, GAI began severe and nonsevere thunderstorm case studies that may lead to future meteorological and aviation applications of LDAR II. To date findings have included: (1) lightning height signatures prior to tornado onset in a supercell, (2) a lightning signature that appears to be mapping and may be linked to a thunderstorm gust front and (3) a lightning hook echo type of feature found prior to a radar base reflectivity hook echo within a tornadic supercell. In addition, a specific case involving an extensive "spider lightning" discharge will be presented. This discharge originated at a distance of more than 50 km from DFW airport, traveled a total path of more than 100 km, and initiated four isolated cloud-to-ground discharges - one of which resulted in a safety-related incident at DFW airport.