The U.S. National Lightning Detection Network & Database (NLDN)

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GCMD, USA —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 (NCC) 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.

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 2 km, with a maximum separation of approximately 7 km.

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.

Read more and learn about access to the database at: http://gcmd.nasa.gov/records/GCMD_NLDN.html

About The GCMD

NASA’s Global Change Master Directory (GCMD) holds more than 25,000 Earth science data set and service descriptions, which cover subject areas within the Earth and environmental sciences.?? The project mission is to assist researchers, policy makers, and the public in the discovery of and access to data, related services, and ancillary information (which includes descriptions of instruments and platforms) relevant to global change and Earth science research.

The GCMD evolved from the prototype NASA Master Directory (NMD) as part of the National Space Science Data Center (NSSDC) at NASA/Goddard Space Flight Center to promote the exchange of scientific data sets through the Catalog Interoperability (CI) project.

In the summer of 1987, the CI Working Group (consisting of several U.S. Federal and international agencies) defined the type of information and level of detail that would be contained within the NMD. The first version of the NMD was released during that year.

In 1989, the Committee on Earth Observation Satellites (CEOS) Data Working Group (DWG) established the CEOS International Directory Network (IDN) to foster the exchange of information among international agencies.

In 1990, the Interagency Working Group on Data Management for Global Change (IWGDMGC) adopted the directory as a prototype to facilitate global change research – in response to the challenge by the Earth System Science Committee (ESSC).

Thereafter, the NMD was renamed the Global Change Master Directory (GCMD) for its Earth sciences applications. In 1994, the GCMD project became part of the Global Change Data Center within the Earth Sciences Directorate at NASA/GSFC, where it still resides.

Today, the GCMD is one of the largest public metadata inventories in the world. The GCMD???s primary responsibility is to maintain a complete catalog of all NASA???s Earth science data sets and services.

The project also serves as one of NASA???s contributions to the international Committee on Earth Observation Satellites (CEOS), through which it is known as the CEOS International Directory Network (IDN).

More online at: http://gcmd.nasa.gov/index.html