Acoustic Location of Lightning with Dense Arrays

Abstract:

In previous work we have shown that it is possible to map lightning sources in three spatial dimensions using acoustic arrays of 4 microphones forming an aperture of about 50 meters. These systems were found to have good performance, with location uncertainty as low as 150 m. However, with only 4 microphones, the solution to the source location is not heavily overdetermined, and sources are frequently located far away from the lightning channel. In an attempt to correct these outlier sources, and to improve the overall accuracy of acoustic localization of lightning, a pilot study was initiated for the 2014 storm season exploring the possibility of locating lightning with dense acoustic arrays. To do this, a large array containing 12 microphones, 150 m by 50 m in diameter was deployed at Langmuir Laboratory in central New Mexico. The larger number of microphones, and the longer baselines should improve the angular uncertainty of acoustic source locations. In addition, it may be possible to distinguish and separate multiple acoustic sources which arrive simultaneously at the array. We will present lightning mapping for a triggered flash that occurred about 600 m from the acoustic array, as well as data for a natural lightning flash. Improvement to the accuracy of acoustic localization can then be determined by comparing the acoustic map with the mapping produced by the Langmuir Lightning Mapping Array.