NEXRAD Radar at NSSL

NEXRAD or Nexrad (Next-Generation Radar) is a network of 158 high-resolution Doppler radars operated by the National Weather Service, an agency of the National Oceanic and Atmospheric Administration (NOAA), in the United States. Its technical name is WSR-88D, which stands for Weather Surveillance Radar, 1988, Doppler. NEXRAD detects precipitation and atmospheric movement or wind. It returns data which when processed can be displayed in a mosaic map which shows patterns of precipitation and its movement. The radar system operates in two basic modes, selectable by the operator: a slow-scanning clear-air mode for analyzing air movements when there is little or no activity in the area, and a precipitation mode with a faster scan time for tracking active weather. NEXRAD has an increased emphasis on automation, including the use of algorithms and automated volume scans. NEXRAD Radar located at The National Severe Storms Labratory in Norman, Oklahoma. ... NEXRAD Radar located at The National Severe Storms Labratory in Norman, Oklahoma. ... The National Severe Storms Laboratory (NSSL) is a weather research laboratory based in Norman, Oklahoma. ... Doppler radar uses the Doppler effect to measure the relative velocity information from a radar system. ... The National Weather Service (NWS) is one of the six scientific agencies that make up the National Oceanic and Atmospheric Administration (NOAA) of the United States government. ... The National Oceanic and Atmospheric Administration (NOAA) is a scientific agency of the United States Department of Commerce focused on the conditions of the oceans and the atmosphere. ... Layers of Atmosphere (NOAA) Earths atmosphere is a layer of gases surrounding the planet Earth and retained by the Earths gravity. ... Wind is the roughly horizontal movement of air (as opposed to an air current) caused by uneven heating of the Earths surface. ... Data is the plural of datum. ... Mosaic is the art of decoration with small pieces of colored glass, stone or other material. ... Automation (ancient Greek: = self dictated) or industrial automation or numerical control is the use of control systems (e. ... Flowcharts are often used to represent algorithms. ...

Deployment

After more than 30 years of research on operational Doppler radar systems, the National Weather Service (NWS) began to deploy the WSR-88D in 1988. It replaced WSR-74 and even WSR-57 units from 1974 and 1957 respectively. The first installation was completed in the Fall of 1990 in Norman, Oklahoma. The last system was completed in northern Indiana in June of 1997. The site locations were strategically chosen to provide the most overlapping coverage between radars in case one failed during a severe weather event. Where possible, they were co-located with NWS Weather Forecast Offices to permit quicker access to maintenance technicians. NEXRAD Radar at NSSL NEXRAD or Nexrad (the next-generation radar) is a network of Doppler radars operated by the National Weather Service, an agency of NOAA, the National Oceanic and Atmospheric Administration, in the United States. ... NEXRAD Radar at NSSL NEXRAD or Nexrad (the next-generation radar) is a network of Doppler radars operated by the National Weather Service, an agency of NOAA, the National Oceanic and Atmospheric Administration, in the United States. ... 1974 (MCMLXXIV) was a common year starting on Tuesday (the link is to a full 1974 calendar). ... 1957 (MCMLVII) was a common year starting on Tuesday of the Gregorian calendar. ... Bizzell Library, University of Oklahoma Norman is the largest city in Cleveland County, Oklahoma and is part of the Oklahoma City Metropolitan Statistical Area. ... Official language(s) English Capital Largest city Indianapolis Indianapolis Area  Ranked 38th  - Total 36,418 sq. ... 1997 (MCMXCVII) was a common year starting on Wednesday of the Gregorian calendar. ...

Scan Strategies

Unlike its predecessors, the WSR-88D antenna is not directly controllable by the user. Instead, the radar system continually refreshes its three-dimensional database via one of several predetermined scan patterns. Since the system samples the atmosphere in three-dimensions, there are many variables that can be changed depending on the desired output. There are currently six Volume Coverage Patterns (VCP) available to NWS meteorologists. Each VCP is a predefined set of instructions given to the antenna that control the rotation speed, transmit/receive mode, and elevation angles. They use a specific numbering scheme:

• Clear Air: VCP 31 and 32 (two digits beginning with 3)
• Shallow Precipitation: VCP 21 (two digits beginning with 2)
• Convection: VCP 11 and 12 (two digits beginning with 1)
• Multiple Pulse Frequency Dealiasing: VCP 121 (three digits beginning with a 1, followed by the 2 digit number of VCP with similar elevation angles)

Future Enhancements

Currently, a large hardware upgrade to the Radar Data Acquisition (RDA) units is underway. The original hardware and software at the radar sites had very limited expandability. To enable more efficient future enhancements to radar products, an "Open RDA" is being installed at all WSR-88D sites nationwide. In addition to large increases in computing power, the new software architecture allows for easier installation of upgrades, including the latest algorithms. This will pave the way for numerous planned improvements over the next decade.

The next major upgrade is likely to be polarimetric radar, which adds vertical polarization to the current horizontal radar waves, in order to more accurately discern what is reflecting the signal. This so-called dual polarization allows the radar to distinguish between rain, hail and snow, something the horizontally polarized radars cannot accurately do. Early trials have shown that rain, sleet, snow, hail, birds, insects, and ground clutter all have different signatures with dual-polarization, which could mark a significant improvement in forecasting winter storms and severe thunderstorms. [1] In electrodynamics, polarization (also spelled polarisation) is a property of waves, such as light and other electromagnetic radiation. ... Horizontal is an orientation relating to, or in parallel with the horizon, and thus perpendicular to the vertical. ... This long range radar antenna, known as ALTAIR, is used to detect and track space objects in conjunction with ABM testing at the Ronald Reagan Test Site on the Kwajalein atoll[1]. Radar is a system that uses radio waves to detect, determine the distance of, and map, objects such... A wave is a disturbance that propagates through space, often transferring energy. ... Rain falling For other uses see Rain (disambiguation). ... Sleet can refer to at least two different forms of precipitation. ... For other uses, see Snow (disambiguation). ... Look up Hail, hail in Wiktionary, the free dictionary. ... Orders Many - see section below. ... Classes & Orders See taxonomy Insects are invertebrate animals of the Class Insecta, the largest and (on land) most widely-distributed taxon within the phylum Arthropoda. ... A typical view of a winter storm. ... A severe thunderstorm is a thunderstorm with winds 58 mph or greater, 3/4 inch or larger hail, or tornadoes. ...

Beyond dual-polarization, the advent of phased array radar will probably be the next giant leap in severe weather detection. Its ability to rapidly scan large areas would give an enormous advantage to radar meteorologists. Any large-scale installation by the NWS is unlikely to occur before the end of the decade. Such a system would more likely be installed separate from the existing WSR-88D network, perhaps only in areas like the Great Plains where tornadoes are more common. A giant phased-array radar in Alaska In telecommunication, a phased array is a group of antennas in which the relative phases of the respective signals feeding the antennas are varied in such a way that the effective radiation pattern of the array is reinforced in a desired direction and... The Great Plains is the broad expanse of prairie which lies east of the Rocky Mountains in the United States of America and Canada, covering all or parts of the U.S. states of New Mexico, Texas, Oklahoma, Colorado, Kansas, Nebraska, Wyoming, Montana, South Dakota and North Dakota and the... For other uses of Tornado, see Tornado (disambiguation). ...

See also

External links

• http://weather.noaa.gov/radar/national.html
• http://www.srh.noaa.gov/srh/sod/radar/radinfo/radinfo.html
• http://www.srh.noaa.gov/srh/sod/radar/radinfo/about.html
• http://www.nssl.noaa.gov/researchitems/radar.shtml
• http://www.wunderground.com/radar/help.asp