83rd Annual

Monday, 10 February 2003
Path to NEXRAD: Doppler Radar Development at the National Severe Storms Laboratory During the 1960s and 1970s
Rodger A. Brown, NOAA/NSSL, Norman, OK; and J. M. Lewis
Poster PDF (24.4 kB)
The weather forecast and warning services in the United States make extensive use of data available from the national network of NEXRAD (Next Generation Weather Radar) or WSR-88D (Weather Surveillance Radar - 1988 Doppler) operational Doppler radars. From the mid 1960s through the end of the 1970s, engineering developments and meteorological studies at the National Severe Storms Laboratory (NSSL) helped to pave the way for the NEXRAD radars.

In the late 1960s, NSSL decided to start development of a 10-cm wavelength Doppler radar that would be suitable for improving the detection and warning of severe storms. This decision was based on blind faith, because, at that time, mean Doppler velocity values could not be processed in real time and, even if they could, the black-and-white displays available were not well-suited for displaying the wide range of Doppler velocity values. NSSL's first 10-cm Doppler radar became operational in 1971 and the second one in 1974. By the mid 1970s, several crucial elements fell into place at NSSL: measurements indicated that Doppler velocity mesocyclone signatures preceded tornado occurrence by several tens of minutes, dual-Doppler radar studies confirmed that mesocyclone signatures represent rotation, case studies found that a tornadic vortex signature appears aloft before the tornado touches ground. At the same time, elsewhere in the country, the pulse pair processor had been perfected for computing mean Doppler velocity in real time and color displays became available for presenting the real-time Doppler radar measurements.

Based on these developments, the National Weather Service, Federal Aviation Administration, and U. S. Air Force were anxious to determine whether the Doppler velocity signatures could be used to increase the timeliness and accuracy of severe weather warnings. Accordingly, the three agencies set up the Joint Doppler Operational Project (JDOP) at NSSL during the Springs of 1977-79 to test whether the signatures had real-time operational applications. JDOP proved to be an outstanding success and the three agencies established a joint office in 1980 to start procurement of the national network of NEXRAD radars.

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