Houston LDAR II network: design, operation, and performance analysis

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Title: Houston LDAR II network: design, operation, and performance analysis
Author: Ely, Brandon Lee
Abstract: The Houston LDAR II network is an array of twelve VHF time -of -arrival (TOA ) sensors operated by Texas A &M University . The goals of the network are to conduct indepth studies of thunderstorm electrification and provide timely lightning threats to the Houston area . Before analyses are conducted using data from the Houston LDAR network , it is necessary to understand the LDAR network ? s performance and limitations , such as the LDAR source detection efficiency , network range , and location accuracy . Initial results from the 31 October 2005 Mesoscale Convective System (MCS ) timing error analysis revealed an RMS timing error for the Houston LDAR network of 90 ns for 6 sensor solutions . This gives a three -dimensional location accuracy of 1 km at a distance of 150 km and 100 m over the center of the network . Reanalysis with updated sensor positions decreased the RMS timing error to 75 ns . This decrease in RMS timing error increased the median three -dimensional location accuracy by ~100 m at a 100 km range . The network has been operated at both 70 MHz and 40 MHz . Model results of detection efficiency suggest that the change to 40 MHz yields an increase of 9 - 10 dB in network sensitivity . Analysis of VHF source power distributions shows a similar shift from that expected from the model . These results show that the 40 MHz LDAR network detects ~3 .3 times more VHF sources than the 70 MHz network . The analysis of the usable network range for research purposes is currently set by rough guidelines of location accuracy and detection efficiency . For location accuracy , a 1 km limit allows storm analysis out to a range of more than 150 km . For the detection efficiency analysis , results based on source power distributions suggest a gradual fall off with range . Examining the change in VHF source density by range reveals different results . VHF source density remained fairly constant out to a range of 100 km at which point a significant fall off was observed . Based on these results the usable network range for the Houston network is 100 km .
URI: http : / /hdl .handle .net /1969 .1 /85993
Date: 2008-10-10

Citation

Houston LDAR II network: design, operation, and performance analysis. Available electronically from http : / /hdl .handle .net /1969 .1 /85993 .

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