A COMBINED TOA MDF TECHNOLOGY UPGRADE OF THE US NATIONAL LIGHTNING DETECTION NETWORK/

The U.S. National Lightning Detection Network(TM) (NLDN) has provided lightning data covering the continental United States since 1989. Usin g information gathered from more than 100 sensors, the NLDN provides b oth real-time and historical lightning data to the electric utility in dustry, the National Weather Service, and other government and commerc ial users. It is also the primary source of lightning data for use in research and climatological studies in the United States. In this pape r we discuss the design, implementation, and data from the time-of-arr ival/magnetic direction finder (TOA/MDF) network following a recent sy stem-wide upgrade. The location accuracy (the maximum dimension of a c onfidence region around the stroke location) has been improved by a fa ctor of 4 to 8 since 1991, resulting in a median accuracy of 500 m. Th e expected flash detection efficiency ranges from 80% to 90% for those events with peak currents above 5 kA, varying slightly by region. Sub sequent strokes and strokes with peak currents less than 5 kA can now be detected and located; however, the detection efficiency for these e vents is not quantified in this study because their peak current distr ibution is not well known.