NSSL Doppler

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NSSL Doppler
Doppler Weather Radar - NOAA.jpg
NSSL Doppler, c. 1971
No. built1
Type Weather radar
Frequency2.7 - 2.9 GHz
PRF 1300 Hz (nominal)
Pulsewidth1 μs (nomimal)
Diameter9.1 m
Azimuth 360º
Elevation0°- 90°
Power500 kW

NOAA's 10 cm Doppler Weather Radar was a 10 cm wavelength S-band Doppler Weather Radar commonly referred to as NSSL Doppler, and was used to track severe weather and related meteorological phenomena. The radar became operational soon after its donation, collecting its first data in May 1971. Data was collected on magnetic tapes and processed on a NASA computer post event due to the lack of real-time capability at the time. [1]



In the early 1940s, radar operators throughout Europe noticed that, when using radar to track objects otherwise concealed due to distance, haze, or otherwise, precipitation was also visible, causing issues when it came to masking and objects within cores of precipitation. Into the late-1940s, scientists from Europe and the United States began to expand on the idea of radar for meteorological applications. In the mid-1950s, the advent of Doppler radar came into light, and many radars in the United States were soon Doppler. [2]


Initially, the NSSL acquired a 3 cm Doppler research radar, which, for the first time, was able to measure object motion within a thunderstorm. Using the Doppler Effect, the radar would detect a change in frequency that occurred when its signal was reflected from a moving target, such as a cluster of raindrops — similar to the shift in frequency experienced with a passing sound. However, it was quickly found that 3 cm Wavelength radars were not sufficient for large-scale detection of severe weather. [3] In 1969, the U.S. Air Force donated a surplus Bendix AN/FPS-18 Radar to the NSSL. [4] This radar, equipped with Doppler capabilities, aided in the discovery of a radar phenomena known as a Tornado Vortex Signature, a small-scale Doppler velocity circulation pattern noted before or during tornadic development. After this was built, a second 10 cm Doppler Radar was built in Canadian County, Oklahoma, establishing Dual-Doppler capabilities for the first time. [5]

Related Research Articles

Radar Object detection system using radio waves

Radar is a detection system that uses radio waves to determine the distance (ranging), angle, or velocity of objects. It can be used to detect aircraft, ships, spacecraft, guided missiles, motor vehicles, weather formations, and terrain. A radar system consists of a transmitter producing electromagnetic waves in the radio or microwaves domain, a transmitting antenna, a receiving antenna and a receiver and processor to determine properties of the object(s). Radio waves from the transmitter reflect off the object and return to the receiver, giving information about the object's location and speed.

Doppler radar

A Doppler radar is a specialized radar that uses the Doppler effect to produce velocity data about objects at a distance. It does this by bouncing a microwave signal off a desired target and analyzing how the object's motion has altered the frequency of the returned signal. This variation gives direct and highly accurate measurements of the radial component of a target's velocity relative to the radar.

Millimeter cloud radar

Millimeter-wave cloud radars, also denominated cloud radars, are radar systems designed to monitor clouds with operating frequencies between 24 and 110 GHz. Accordingly, their wavelengths range from 1 mm to 1.11 cm, about ten times shorter than those used in conventional S band radars such as NEXRAD.

NEXRAD Nationwide network of Doppler weather radars operated by the U.S. National Weather Service

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Weather radar Radar used to locate and monitor meteorological conditions

Weather radar, also called weather surveillance radar (WSR) and Doppler weather radar, is a type of radar used to locate precipitation, calculate its motion, and estimate its type. Modern weather radars are mostly pulse-Doppler radars, capable of detecting the motion of rain droplets in addition to the intensity of the precipitation. Both types of data can be analyzed to determine the structure of storms and their potential to cause severe weather.

Hook echo Weather radar signature indicating tornadic circulation in a supercell thunderstorm

A hook echo is a pendant or hook-shaped weather radar signature as part of some supercell thunderstorms. It is found in the lower portions of a storm as air and precipitation flow into a mesocyclone, resulting in a curved feature of reflectivity. The echo is produced by rain, hail, or even debris being wrapped around the supercell. It is one of the classic hallmarks of tornado-producing supercells. The National Weather Service may consider the presence of a hook echo coinciding with a tornado vortex signature as sufficient to justify issuing a tornado warning.

Pulse-Doppler radar

A pulse-Doppler radar is a radar system that determines the range to a target using pulse-timing techniques, and uses the Doppler effect of the returned signal to determine the target object's velocity. It combines the features of pulse radars and continuous-wave radars, which were formerly separate due to the complexity of the electronics.

The National Severe Storms Laboratory (NSSL) is a National Oceanic and Atmospheric Administration (NOAA) weather research laboratory under the Office of Oceanic and Atmospheric Research. It is one of seven NOAA Research Laboratories (RLs).

Aggie Doppler Radar

The Aggie Doppler Radar (ADRAD) is a Doppler weather radar located on the roof of the Eller Oceanography & Meteorology Building on the Texas A&M University campus in College Station, Texas.

The King City weather radar station is a weather radar located in King City, Ontario, Canada. It is operated by Environment Canada and is part of the Canadian weather radar network, for which it is the primary research station.

The J.S. Marshall Radar Observatory is a McGill University facility in Sainte-Anne-de-Bellevue, Quebec, Canada housing several weather radars and other meteorological sensors, many of them running around the clock. It is one of the components of the McGill Atmospheric and Oceanic Sciences department where students in remote sensing perform their research. Furthermore, the main radar is part of the Canadian weather radar network, was on a contract with the Meteorological Service of Canada, as well as a research device, up to October 3, 2018.

Canadian weather radar network

The Canadian weather radar network consists of 31 weather radars spanning Canada's most populated regions. Their primary purpose is the early detection of precipitation, its motion and the threat it poses to life and property.

Convective storm detection is the meteorological observation, and short-term prediction, of deep moist convection (DMC). DMC describes atmospheric conditions producing single or clusters of large vertical extension clouds ranging from cumulus congestus to cumulonimbus, the latter producing thunderstorms associated with lightning and thunder. Those two types of clouds can produce severe weather at the surface and aloft.

Outline of meteorology Overview of and topical guide to meteorology

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Tornado vortex signature

A tornadic vortex signature, abbreviated TVS, is a Pulse-Doppler radar weather radar detected rotation algorithm that indicates the likely presence of a strong mesocyclone that is in some stage of tornadogenesis. It may give meteorologists the ability to pinpoint and track the location of tornadic rotation within a larger storm, but it is not an important feature in the National Weather Service's warning operations.

VORTEX projects

The Verification of the Origins of Rotation in Tornadoes Experiment are field experiments that study tornadoes. VORTEX1 was the first time scientists completely researched the entire evolution of a tornado with an array of instrumentation, enabling a greater understanding of the processes involved with tornadogenesis. A violent tornado near Union City, Oklahoma was documented in its entirety by chasers of the Tornado Intercept Project (TIP) in 1973. Their visual observations led to advancement in understanding of tornado structure and life cycles.

Terminal Doppler Weather Radar

Terminal Doppler Weather Radar (TDWR) is a Doppler weather radar system with a three-dimensional "pencil beam" used primarily for the detection of hazardous wind shear conditions, precipitation, and winds aloft on and near major airports situated in climates with great exposure to thunderstorms in the United States. As of 2011, all were in-service with 45 operational radars, some covering multiple airports in major metropolitan locations, across the United States & Puerto Rico. Several similar weather radars have also been sold to other countries such as China. Funded by the United States Federal Aviation Administration (FAA), TDWR technology was developed in the early 1990s at Lincoln Laboratory, part of the Massachusetts Institute of Technology, to assist air traffic controllers by providing real-time wind shear detection and high-resolution precipitation data.


The Shared Mobile Atmospheric Research and Teaching Radar, colloquially known as SMART-R or SR, is a mobile Doppler weather radar platform operated and created by University of Oklahoma (OU) with aide from Texas A&M and Texas Tech University in 2001.

Roger Lhermitte

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Project NIMROD

Project NIMROD was a meteorological field study of severe thunderstorms and their damaging winds conducted by the National Center for Atmospheric Research (NCAR). It took place in the Greater Chicago area from May 15 to June 30, 1978. Data collected was from single cell thunderstorms as well as mesoscale convective systems, such as bow echoes. Using Doppler weather radars and damage clues on the ground, the team studied mesocyclones, downbursts and gust fronts. NIMROD was the first time that microbursts, very localized strong downdrafts under thunderstorms, were detected; this helped improve airport and public safety by the development of systems like the Terminal Doppler Weather Radar and the Low-level windshear alert system.


  1. "NSSL History".
  2. http://www.meteor.iastate.edu/~jdduda/portfolio/HistoryPPT.pdf [ bare URL PDF ]
  3. "Weather radar highlights of NSSL's first 40 years".
  4. Brown, Rodger A.; Bumgarner, William C.; Crawford, Kenneth C.; Sirmans, Dale (1971). "Preliminary Doppler Velocity Measurements in a Developing Radar Hook Echo". Bulletin of the American Meteorological Society. 52 (12): 1186–1188. Bibcode:1971BAMS...52.1186B. doi: 10.1175/1520-0477(1971)052<1186:PDVMIA>2.0.CO;2 . ISSN   1520-0477.
  5. "Weather radar highlights of NSSL's first 40 years".