Accuracy of the Lightning Mapping Array

Abstract

[1] The location accuracy of the New Mexico Tech Lightning Mapping Array (LMA) has been investigated experimentally using sounding balloon measurements, airplane tracks, and observations of distant storms. We have also developed simple geometric models for estimating the location uncertainty of sources both over and outside the network. The model results are found to be a good estimator of the observed errors and also agree with covariance estimates of the location uncertainties obtained from the least squares solution technique. Sources over the network are located with an uncertainty of 6-12 m rms in the horizontal and 20-30 m rms in the vertical. This corresponds well with the uncertainties of the arrival time measurements, determined from the distribution of chi-square values to be 40-50 ns rms. Outside the network the location uncertainties increase with distance. The geometric model shows that the range and altitude errors increase as the range squared, r 2 , while the azimuthal error increases linearly with r. For the 13 station, 70 km diameter network deployed during STEPS the range and height errors of distant sources were comparable to each other, while the azimuthal errors were much smaller. The difference in the range and azimuth errors causes distant storms to be elongated radially in plan views of the observations. The overall results are shown to agree well with hyperbolic formulations of time of arrival measurements [e.g., Proctor, 1971]. Two appendices describe (1) the basic operation of the LMA and the detailed manner in which its measurements are processed and (2) the effect of systematic errors on lightning observations. The latter provides an alternative explanation for the systematic height errors found by Boccippio et al. [2001] in distant storm data from the Lightning Detection and Ranging system at Kennedy Space Center.

Asymmetries in bidirectional leader development of lightning flashes

“…[7] In July 2011, a six-station Lightning mapping array (LMA) [Rison et al, 1999;Thomas et al, 2004] was deployed in the Ebro Delta (eastern Spain, Figure 1). Over the course of 2012, the system was gradually expanded to 11 stations.…”

Thunderstorm observations by air-shower radio antenna arrays

“…Several radio antenna arrays have been built or are going to be constructed, where LOPES in Karlsruhe served as the ground breaker for this cosmic ray detection technique. The Auger Engineering Radio Array AERA at the Pierre Auger Observatory in Argentina, presently being constructed, is the first array of a large scale application of the technique (van den Berg et al, 2009).…”

“…By deploying different types of radio antennas and highly sensitive electric field mills a lightning can be observed with a spatial resolution of around 10 m and time resolution of about 40 ns (Thomas et al, 2004). Data from the LMA stations can then be combined to provide threedimensional images of the lightning channels, including lightning initiation positions and times of occurrence.…”

Lightning Imaging with LOFAR

“…To determine the position in the atmosphere of the source that emitted the radio signal one measures the time of arrival (ToA) in a network of antennas on the ground. To reach sufficient accuracy they are spread over distances of typically 60 km [9]. Most arrays operate in an abandoned TV broadcasting frequency band in the lower VHF band, 60-66 MHz where the signal is digitized at a frequency of 25 MHz.…”