Atmospheric Measurement Techniques Discussions
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2010
10.5194/amtd-3-1861-2010
http://www.atmos-meas-tech-discuss.net/3/1861/2010/
http://www.atmos-meas-tech-discuss.net/3/1861/2010/amtd-3-1861-2010.html
http://www.atmos-meas-tech-discuss.net/3/1861/2010/amtd-3-1861-2010.pdf
1861
1887
2010-04-20
A performance assessment of the World Wide Lightning Location Network (WWLLN) via comparison with the Canadian Lightning Detection Network (CLDN)
D. Abreu
D. Chandan
R. H. Holzworth
K. Strong
strong@atmosp.physics.utoronto.ca
Department of Physics, University of Toronto, Ontario, Canada
Departments of Earth and Space Sciences, and Physics, University of Washington, Washington, USA
The World Wide Lightning Location Network (WWLLN) uses globally-distributed
Very Low Frequency (VLF) receivers in order to observe lightning around the
globe. Its objective is to locate as many global strokes as possible, with
high temporal and spatial (<10 km) accuracy. Since detection is done in
the VLF range, signals from high peak current lightning strokes are able to
propagate up to ~10<sup>4</sup> km before being detected by the WWLLN
sensors, allowing for receiving stations to be sparsely spaced.
<br><br>
Through a comparison with measurements made by the Canadian Lightning
Detection Network (CLDN) between May and August 2008 over a 4° latitude
by 4° longitude region centered on Toronto, Canada, this study found
that WWLLN detection was most sensitive to high peak current lightning
strokes. Events were considered shared between the two networks if they fell
within 0.5 ms of each other. Using this criterion, 19 128 WWLLN strokes
(analyzed using the Stroke_B algorithm) were shared with CLDN lightning
strokes, producing a detection efficiency of 2.8%. The peak current
threshold for WWLLN detection is found to be ~20 kA, with the
detection efficiency increasing to ~70% at peak currents of ±120 kA.
The detection efficiency is seen to have a clear diurnal
dependence, with a higher detection efficiency at local midnight than at
local noon; this is attributed to the difference in the thickness of the
ionospheric D-region between night and day. The mean time difference (WWLLN – CLDN)
between shared events was −6.44 μs with a standard deviation
of 35 μs, and the mean absolute location accuracy was 7.24 km with a
standard deviation of 6.34 km. These results are generally consistent with
previous comparison studies of the WWLLN with other regional networks around
the world. Additional receiver stations are continuously being added to the
network, acting to improve this detection efficiency.
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