From Glossary of Meteorology


(Abbreviation for Weather Surveillance Radar–1988 Doppler.) The weather radar, sometimes called NEXRAD, that became the operational network radar for the U.S. National Weather Service, U.S. Air Force, and Federal Aviation Administration during the early and middle 1990s.

It is a general-purpose weather radar with a wavelength of 10.5 cm, a peak power of 750 kW, selectable pulse duration of 1.57 or 4.0 μs, and selectable pulse repetition frequency from 318 to 1304 Hz. A coherent Doppler radar, it employs a center-fed parabolic antenna with a diameter of 8.5 m, producing a beamwidth of 0.95°. Received signals are analyzed using the method of pulse-pair processing to give as fundamental data the reflectivity factor, mean Doppler velocity, and Doppler spread as functions of time and location relative to the radar. The maximum unambiguous range is ordinarily 460 km for reflectivity and 115 km for Doppler information. Many kinds of computer algorithms are employed for identifying features such as vortices, downbursts, and fronts.

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