HR: 1340h
AN: AE33A-0176    [Abstracts]
TI: A Preliminary ZEUS Lightning Location Error Analysis Using a Modified Retrieval Theory
AU: * Elander, V
EM: elanderv@unlv.nevada.edu
AF: University of Nevada - Las Vegas Department of Mathematical Sciences, 4505 Maryland Parkway PO Box 454020, Las Vegas, NV 89154-4020 United States
AU: Koshak, W
EM: william.koshak@nasa.gov
AF: NASA - MSFC, SD60 National Space Science & Technology Center, 320 Sparkman Drive, Huntsville, AL 35805 United States
AU: Phanord, D
EM: phanordd@unlv.nevada.edu
AF: University of Nevada - Las Vegas Department of Mathematical Sciences, 4505 Maryland Parkway PO Box 454020, Las Vegas, NV 89154-4020 United States
AB: The ZEUS long-range VLF arrival time difference lightning detection network now covers both Europe and Africa, and there are plans for further expansion into the western hemisphere. In order to fully optimize and assess ZEUS lightning location retrieval errors and to determine the best placement of future receivers expected to be added to the network, a software package is being developed jointly between the NASA Marshall Space Flight Center (MSFC) and the University of Nevada Las Vegas (UNLV). The software package, called the ZEUS Error Analysis for Lightning (ZEAL), will be used to obtain global scale lightning location retrieval error maps using both a monte carlo approach and chi-squared curvature matrix theory. At the core of ZEAL will be an implementation of an Iterative Oblate (IO) lightning location retrieval method recently developed at MSFC [Koshak and Solakiewicz, TOA Lightning Location Retrieval on Spherical and Oblate Spheroidal Earth Geometries, J. Atmos. and Oceanic. Tech., 187-199, 2001.] The IO method will be appropriately modified to account for variable wave propagation speed, and the new retrieval results will be compared with the current ZEUS retrieval algorithm to assess potential improvements. In this preliminary ZEAL work effort, we defined 5000 source locations evenly distributed across the Earth. We then used the existing (as well as potential future ZEUS sites) to simulate arrival time data between source and ZEUS site. A total of 100 sources were considered at each of the 5000 locations, and timing errors were selected from a normal distribution having a mean of 0 seconds and a standard deviation of 20 microseconds. This simulated "noisy" dataset was analyzed using the IO algorithm to estimate source locations. The exact locations were compared with the retrieved locations, and the results are summarized via several color-coded "error maps."
DE: 3324 Lightning
DE: 3337 Numerical modeling and data assimilation
DE: 3230 Numerical solutions
DE: 3260 Inverse theory
SC: Atmospheric and Space Electricity [AE]
MN: 2004 AGU Fall Meeting