The Physical and Meteorological Characteristics Associated with Lightning Flashes

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9806189 Orville We grant a three-year continuation of NSF ATM-92 13787 using data from the National Lightning Detection Network (NLDN) with supporting information from radar and satellite observations. There are two parts to the proposed research that we will simultaneously pursue. First, we propose to continue our investigations into the physical and meteorological conditions associated with cloud-to-ground lightning flashes. This will include continued analysis in the following areas, a) NLDN lightning records in the United States, to include peak currents, polarity, and multiplicity and their variation from year to year, with seasons, from month to month, from storm to storm, and within storms, b) research on the lightning in mesoscale convective complexes in Texas, c) the forecasting of active lightning days, and d) the characteristics of winter lightning. Second, we will investigate the NLDN reliability by determining the reasons behind the increased positive flash counts and lowering of the annual mean peak current in cloud-to-ground flashes. We will do this by using a recently installed Advanced Lightning Direction Finder and a Brook waveform digitizing recording system to obtain waveforms on lightning within a few hundred kilometers of Texas A&M University. We propose, also, to measure the detection efficiency of the NLDN at College Station, Texas. This research will contribute to the education of several graduate students who will directly participate in the proposed research, which will include their sharing in data acquisition and analysis. Included in this proposal is support for graduate students who will write theses and dissertations and present their results at seminars and professional meetings, and write manuscripts describing their research. Research results will be incorporated into advanced courses on cloud physics and mesoscale phenomena. Undergraduates will be involved from the Departments of Meteorology, Electrical Engineering, and Computer Science.