Abstract:
The National Lightning Detection Network, NLDN, consists of over
100 remote, ground-based sensing stations located across the
United States that instantaneously detect the electromagnetic
signals given off when lightning strikes the earth's
surface. These remote sensors send the raw data via a
... satellite-based communications network to the Network Control
Center operated by Vaisala Inc. in Tucson, Arizona. Within
seconds of a lightning strike, the NCC?s central analyzers
process information on the location, time, polarity, and
amplitude of each strike. The lightning information is then
communicated to users across the country.
REAL TIME / ARCHIVE DATA
------------------------
Lightning data collected by the NLDN is available for use in two
different categories, real time and archive. Real time data
subscribers receive live, second-by-second data on lightning
activity within their own designated area of application, up to
and including the 48 contiguous states.
The NLDN's vast archive data library contains over 160 million
flashes from 1989 to the present. Data can be provided in ASCII
format for analysis on a users' own workstation, or provided in
packed binary formats for display and analysis via GAI display
software. Analytical services and reports produced by trained
GAI personnel are also available for tailored historical studies
or specific geographical evaluations.
FLASH / STROKE DATA
-------------------
Flash data provides information such as the time, location,
polarity, and amplitude of each lightning flash. Recent studies,
however, have shown there can be as many as 20 return strokes in
a flash. Further, approximately half of the flashes contain
subsequent strokes that terminate at more than one location. The
mean separation of these strike points averages 2km, with a
maximum separation of approximately 7km.
Stroke data, available since January 1, 1995, refines and
expands on flash data by recording characteristics of each
detected subsequent stroke. The stroke data set provides such
detail that a whole new level of analyses and in-depth lightning
exposure investigations can now be performed. Lightning damage
or exposure studies require this information for an accurate
assessment of lightning activity.
CUSTOM DISPLAY SOFTWARE
-----------------------
NLDN data is accessible to subscribers through various DOS,
Windows, or Unix-based display and analytical software. These
programs are high performance graphical systems designed for
effective interpretation and analysis of lightning
information. Real time lightning data is received for display
via satellite broadcast and dial-up telephone
communications. Archived lightning data can be obtained on
diskette from the NLDN, or archived on site by a user through
custom software. Lightning data can be displayed in contour or
other formats to identify high-risk areas, and can be
color-coded or animated to track developing storms.
http://thunderstorm.vaisala.com 
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