Information AboutNexrad |
| CATEGORIES ABOUT NEXRAD | |
| national weather service | |
| weather radars | |
| radar networks | |
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NEXRAD or '''Nexrad''' ('''Nex'''t-Generation '''Rad'''ar) is a network of 158 high-resolution , including the use of Algorithm s and automated volume scans. 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 , however, the first installation of a WSR-88D for use in everyday forecasts was in Sterling, Virginia on June 12 , 1992 . The last system was installed in North Webster, Indiana on August 30 , 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. WSR-88D Radar, Tornado Warnings and Tornado Casualties 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:
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 Wave s, 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 , Bird s, Insect s, and Ground Clutter all have different signatures with dual-polarization, which could mark a significant improvement in forecasting Winter Storm s and Severe Thunderstorm s. {Link without Title} 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. SEE ALSO EXTERNAL LINKS
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