Calibrated Radar Rainfall Data
History of Calibrated Radar Rainfall
The NEXRAD radar system was installed coast-to-coast in the United
States in the early 1990s. (See map for locations.) The National Weather
Service developed the NEXRAD system to improve detection of severe weather.
NEXRAD is the acronym for "next generation radar." It is also
known as WSR-88D (88 stands for the development year—1988—and
D represents "Doppler"). The system is commonly referred to
as NEXRAD or Doppler radar. Since 1992, more than 158 NEXRAD sites
have been implemented nationwide.
Radar does not measure rainfall directly, but rather detects the intensity
of microwave energy reflected by raindrops, called reflectivity. Through
the use of a mathematical formula (algorithm), the reflectivity of the raindrops
can be converted by the radar system into rainfall estimates. These estimates,
combined with actual rain gauge data, can provide an accurate and valuable
source of rainfall information over large geographic areas.
Vieux & Associates, Inc. calibrates the radar reflectivity with the
actual rain gauge data provided by 3 Rivers Wet Weather, and posts this information
in a database for later retrieval via this website.
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