EAGER: Multi-frequency Studies of Lightning Initiation and Propagation

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Lightning is one of the worst natural hazards, killing more people in the USA on average than hurricanes or tornadoes [see http://www.nws.noaa.gov/om/hazstats.shtml] and causing substantial damage to property and sensitive equipment. Although lightning flashes have been studied for many decades, several fundamental aspects of lightning physics are still not understood, including how they begin (initiate) and how they travel (propagate) through clouds and clear air to the ground. This research project will focus on lightning initiation and lightning propagation in a new way to help explain how these two fundamental aspects of lightning may work. The measurements proposed will be made at the NASA Kennedy Space Center (KSC) in Florida. Lightning is especially frequent at KSC, causes expensive operational delays, and sometimes damages sensitive rocket and shuttle vehicles and/or facilities.The observation scheme for this project is to use five different 'eyes' (measurement systems) to observe lightning processes: (1) slow antennas, (2) fast antennas, (3) a network of seven crossed-loop magnetic sensors, (4) the KSC field mill network and (5) the KSC Lightning Detection And Ranging (LDAR) system. All of these sensors look at the electric or magnetic changes caused by lightning as it accelerates and moves charge. The five types of sensors are well known in lightning research, but all five have never before been used together to observe flashes. The different instruments respond to different parts of a flash: some parts are only a few meters in length while others are as long as a few thousand meters. A key feature of this project will be the use of a recently developed technique for the crossed-loop sensor network that allows one to determine the location of long (~1000 meter), fast electromagnetic pulses from lightning. The locations of these long pulses, found in both in-cloud and cloud-to-ground lightning flashes, have not been known in the past. The intellectual merit of the project stems from combining the data from these five sensors to provide new insights into how lightning initiation and lightning propagation work.The main broader impacts of the project fall into two categories: improving lightning safety and training new scientists. Developing a better understanding of the mechanisms behind a particular hazard (lightning, in this case) can lead to new and improved ways of protecting people and property from that hazard. Lightning protection systems are primarily based in science, and determining how lightning initiates and propagates may reveal new ways to protect objects on the ground and in the air. This project will also be important for the development and training of several new scientists, including one graduate student pursuing a Ph.D. degree, and two undergraduate physics students interested in being involved in scientific research. The results of this project will also be broadly disseminated in the peer-reviewed literature.