The National Lightning Detection Network™
"The most sophisticated lightning detection and location system in the world."
The Evolution of Lightning Data
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Mean Annual Thunder Days through 1969 - Estimates of ground flash density were derived by using the number of days with thunder as counted by human observers. |
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Flash Density Contour Map, 1989 - Accurate representation of measured annual ground flash density as detected by the NLDN, provided in contour format. |
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Flash Density Map - Today's technology can provide high resolution, 2 km x 2 km, ground flash density in gridded and other formats. |
THE NLDN
The National Lightning Detection Network, owned and operated by Global Atmospherics, Inc. (GAI), incorporates over 20 years of research and development in lightning detection and location. It is a state-of-the-art lightning location system that provides reliable, cost-effective data to a variety of demanding customers. The Electric Power Research Institute (EPRI) commenced the network's original formation for the purpose of helping utilities make objective decisions regarding line maintenance priorities, effective crew dispatch, and future design and placement of utility lines.
These goals have been achieved and expanded upon to address applications in multiple industries and environments. Major utilities, airlines and government agencies, as well as telecommunications, safety and military installations are just a few of the entities that make daily operational decisions based on data provided by the NLDN.
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.
ABOUT THE NATIONAL LIGHTNING DETECTION NETWORK™
Real time lightning displays provide a clear picture of the current lightning activity while allowing the user to program different levels of warning and alarm notification.
- Sensors transmit data to satellite;
- Satellite relays information to earth station;
- Data is transmitted to NCC via land-lines;
- NCC processes data;
- Processed data is relayed back to satellite;
- Lightning data is displayed within seconds of occurrence
The NLDN consists of over 100 remote, ground-based sensing stations that monitor cloud-to-ground lightning activity across the contiguous 48 states. Using exclusive, patented technologies and powerful electronics, lightning strikes are differentiated from the vast amount of background noise found in the atmosphere.
Within seconds of a lightning strike, central analyzers at the Network Control Center (NCC) process information on the location, time, polarity, and amplitude of each strike via an advanced, satellite-based communications network. Unprecedented location accuracy has been achieved by combining the very precise capabilities of waveform processing, Global Positioning System (GPS) time synchronization, high-speed signal processing, and wide-band peak gated magnetic direction finding techniques. The result is extremely accurate location information and a high level of redundancy for improved data integrity and reliability.
CONTINUOUS MONITORING
Twenty-four hours a day, every day of the year, NCC personnel closely monitor network operations. Every sensor in the network, as well as the NCC itself, is continuously monitored for data quality and proper operation. An aggressive preventative maintenance program and a knowledgeable field service staff ensure that critical lightning information is there when you need it. Every lightning event is accompanied by quality control parameters that provide an objective level of confidence for making informed decisions.
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.