oa Development and Results of the National Lightning Detection Network in the USA

A review will be given of the development, installation, and use of lightning data from detection networks over the last twenty years in the United States. One path will be traced from the first successful efforts in 1979 to overlay lightning locations on radar and satellite images, to the implementation of the National Lightning Detection Network. to recent results from the "enhanced network" now operated by Global Atmospheric Inc., Tucson. Arizona. Our results show that the United States has approximately 30 million cloud-to-ground strikes per year with about 4-9 % lowering positive charge to ground. The monthly values of the percentage of positive flashes ranges from typically 3 % in the summer to 25 % in the winter. The annual maximum flash density in the United States is typically 9-11 flashes/km2 and is usually found in the state of Florida.