Monthly National Lightning Detection Network

(NLDN) cloud to ground lightning data over Florida land areas from 1989 to 2004 reveals interesting trends over the 16 year period. The first major system-wide upgrade was completed in 1995 and added IMPACT lightning sensors combining magnetic direction finding and time-of-arrival detection methods (Cummins et. al., 1998). Flash detection efficiency increased to 80-90 % with a median stroke location accuracy of 500 meters. The second major upgrade was completed in 2003 with installation of Vaisala IMPACT ESP Lightning Sensors throughout the network (Grogan, 2004). This has increased overall flash detection efficiency to 90 % and stroke detection efficiency to 60-80%. For thi