National Lightning Detection Network (NLDN)
Data Available via the Unidata LDM

Vaisala Corporation


The University at Albany, State University of New York, through a cooperative agreement with Vaisala, offers a real-time LDM data feed from the National Lightning Detection Network (NLDN) to United States-based colleges and universities. This feed is available at no cost for education and research, under constraints established by Vaisala and the University at Albany, SUNY. Please note that UAlbany is only able to provide real-time NLDN data. Please contact Vaisala for information regarding requests for archived data.


he University at Albany controls LDM access to the NLDN data. Vaisala's policy prohibits redistribution-of or financial gain-from the NLDN data.

Universities interested in receiving the NLDN data should contact:

UAlbany Department of Atmospheric and Environmental Sciences Support

Kevin Tyle
Department of Atmospheric and Environmental Sciences
University at Albany
State University of New York

Data Details

NLDN data emanates from UAlbany via the Unidata LDM mechanism.

UAlbany runs the LDM server that is the primary distributor for NLDN data. A description of the data records for flash events is contained in the following tables:

NLDN data packet contents
Field Example
date [CCYYMMDD] 19930922
time [HH:MM:SS.msec] 10:22:33.334
latitude 47.33
longitude -87.116 (west negative convention)
polarity/signal strength -188.7
multiplicity 0
ellipse angle 174
semi-major axis 6.0
eccentricity 2.0
chi-square 1.0
NLDN binary data record - big-endian byte order
Size Name Description
char[4] NLDN 'NLDN' marks the start of record
int[4] nhead number of 28 byte header record blocks (includes 'NLDN' and nhead)
char[] (nhead*28 - 8) remaining header bytes (can be ignored)
int[4] tsec seconds since 1970
int[4] nsec nanoseconds since tsec (NB: this appears be milliseconds, not nanoseconds)
int[4] lat latitude [deg] * 1000
int[4] lon longitude [deg] * 1000
short[2] fill padding
short[2] sgnl signal strength * 10 (NB: 150 NLDN measures ~= 30 kAmps)
short[2] fill padding
char[1] mult multiplicity (#strokes per flash; zero for IDD-delivered records after 2015)
char[1] fill padding
char[1] semimaj semi-major axis
char[1] eccent eccentricity
char[1] angle ellipse angle
char[1] chisqr chi-square

Data Processing

When a lightning data packet is received by an LDM server, a decoder may be automatically invoked to convert the NLDN-native format to, for example, a Unidata netCDF file, a GEMPAK point file, or a McIDAS MD file. The IDD feedtype, for this datastream is named LIGHTNING (FT14).

Software that allows McIDAS, GEMPAK, and the IDV to use NLDN data is available from Unidata. Contact for further information on how Unidata software may be used to analyze and display NLDN lightning data.


  • VaisalaVaisala's National Lightning Detection Network (NLDN) Lightning Explorer displays recent lightning activity across the entire continental United States.