The Full Wiki

NEXRAD: Map

Advertisements
  
  

Wikipedia article:

Map showing all locations mentioned on Wikipedia article:

NEXRAD or Nexrad (Next-Generation Radar) is a network of 159 high-resolution Doppler weather radars operated by the National Weather Service, an agency of the National Oceanic and Atmospheric Administration (NOAA) within the United States Department of Commercemarker. 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 for tracking active weather. NEXRAD has an increased emphasis on automation, including the use of algorithms and automated volume scans.

Deployment

Source: NOAA
After more than 30 years of research on operational Doppler weather 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, Oklahomamarker, however, the first installation of a WSR-88D for use in everyday forecasts was in Sterling, Virginiamarker on June 12, 1992. The last system was installed in North Webster, Indianamarker 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.

Initial development of the NEXRAD system started in 1982 at the National Severe Storms Laboratory in Norman, Oklahomamarker. Members of the early NEXRAD team included Timothy O'Bannon, a meteorologist and hydrologist who, as an amateur ornithologist also recognized the radar's additional capabilities for tracking bird migration patterns.

Lead contractor was Sperry Corporation and Concurrent Computer supplied the high speed minicomputer processing units.

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)


VCP Scan Time (min) Elevation angles (°) Usage Special attributes

11 5 0.5, 1.5, 2.4, 3.4, 4.3, 5.3, 6.2, 7.5, 8.7, 10, 12, 14, 16.7, 19.5 Convection, especially when close to the radar Has the best overall volume coverage.
12 4 0.5, 0.9, 1.3, 1.8, 2.4, 3.1, 4.0, 5.1, 6.4, 8.0, 10.0, 12.5, 15.6, 19.5 Convection, especially activity at longer ranges Focuses on lower elevations to better sample the lower levels of storms.
121 5.5 0.5, 1.5, 2.4, 3.4, 4.3, 6.0, 9.9, 14.6, 19.5 Large number of rotating storms, tropical systems, or when better velocity data is needed. Scans lower cuts multiple times with varying pulse repetitions to greatly enhance velocity data.
21 6 0.5, 1.5, 2.4, 3.4, 4.3, 6.0, 9.9, 14.6, 19.5 Shallow precipitation Rarely used for convection due to sparse elevation data and long completion time.
31 10 0.5, 1.5, 2.5, 3.5, 4.5 Detecting subtle boundaries or wintry precipitation Long-pulse
32 10 0.5, 1.5, 2.5, 3.5, 4.5 Slow rotation speed allows for increased sensitivity. Default clear-air mode, reduces wear on antenna. Short-pulse


Future enhancements

Super resolution

In the process of implementation from March to June 2008, is the capability of the RDA to produce super resolution data. The WSR-88D provides reflectivity data at 1 km by 1 degree to 460 km range, and Doppler data at 0.25 km by 1 degree to a range of 230 km. Super Resolution will provide data with a sample size of 0.25 km by 0.5 degree, and increase the range of Doppler data to 300 km from the current 230 km. Initially the increased resolution will only be available in the lower scan elevations. Super resolution makes a compromise of slightly decreased noise reduction for a large gain in resolution.

To improve severe weather warning lead times, potential tornadic storms need to be identified as soon as possible. The improvement in beam width resolution increases the range at which small tornado parent circulation patterns (down to 4 km diameter) can be detected. Super-resolution also provides additional detail to aid in severe storm analysis. Extending the range of Doppler data and providing Doppler data earlier in the process of a volume scan provides velocity data more quickly than current scan techniques.As of August 1, 2008, 134 out of 172 nexrad sites provide super resolution.

Polarimetric radar

The next major upgrade is 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, ice pellets, 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.The deployment of the dual polarization capability (Build 12) to NEXRAD sites will begin in 2010 and last until 2012.

Phased array

Beyond dual-polarization, the advent of phased array radar will probably be the next major improvement 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 2010. Such a system would more likely be installed separate from the existing WSR-88D network, perhaps only in areas like the Great Plainsmarker where tornadoes are more common.

Applications

One practical application under experiment is using the mosaic map to suggest alternate flight paths for airliners to avoid turbulence.

In Popular Culture

In the movie Twister, references are made about NEXRAD, in the form of mobile computing systems used by storm chasers containing "NEXRAD realtime."

State Location Identifier Coordinates
PR San Juan TJUA
ME Loring AFB KCBW
ME Portland KGYX
VT Burlington KCXX
MA Boston KBOX
NY Albany KENX
NY Binghamton KBGM
NY Buffalo KBUF
NY Montague KTYX
NY New York City KOKX
DE Dover AFB KDOX
PA Philadelphia KDIX
PA Pittsburgh KPBZ
PA State College KCCX
WV Charleston KRLX
VA Norfolk/Richmond KAKQ
VA Roanoke KFCX
VA Sterling KLWX
NC Morehead City KMHX
NC Raleigh/Durham KRAX
NC Wilmington KLTX
SC Charleston KCLX
SC Columbia KCAE
SC Greer KGSP
GA Atlanta KFFC
GA Moody AFB KVAX
GA Robins AFB KJGX
FL Eglin AFB KEVX
FL Jacksonville KJAX
FL Key West KBYX
FL Melbourne KMLB
FL Miami KAMX
FL Tallahassee KTLH
FL Tampa KTBW
AL Birmingham KBMX
AL Fort Rucker KEOX
AL Huntsville KHTX
AL Maxwell AFB KMXX
AL Mobile KMOB
MS Brandon/Jackson KDGX
MS Columbus AFB KGWX
TN Knoxville/Tri Cities KMRX
TN Memphis KNQA
TN Nashville KOHX
KY Fort Campbell KHPX
KY Jackson KJKL
KY Louisville KLVX
KY Paducah KPAH
OH Wilmington KILN
OH Cleveland KCLE
MI Detroit/Pontiac KDTX
MI Gaylord KAPX
MI Grand Rapids KGRR
MI Marquette KMQT
IN Evansville KVWX
IN Indianapolis KIND
IN North Webster KIWX
IL Chicago KLOT
IL Lincoln KILX
WI Green Bay KGRB
WI La Crosse KARX
WI Milwaukee KMKX
MN Duluth KDLH
MN Minneapolis/St. Paul KMPX
IA Davenport KDVN
IA Des Moines KDMX
MO Kansas City KEAX
MO Springfield KSGF
MO St. Louis KLSX
AR Fort Smith KSRX
AR Little Rock KLZK
LA Fort Polk KPOE
LA Lake Charles KLCH
LA New Orleans KLIX
LA Shreveport KSHV
TX Amarillo KAMA
TX Austin/San Antonio KEWX
TX Brownsville KBRO
TX Corpus Christi KCRP
TX Dallas/Ft. Worth KFWS
TX Dyess AFB KDYX
TX El Paso KEPZ
TX Fort Hood KGRK
TX Houston/Galveston KHGX
TX Laughlin AFB KDFX
TX Lubbock KLBB
TX Midland/Odessa KMAF
TX San Angelo KSJT
OK Frederick KFDR
OK Oklahoma City KTLX
OK Tulsa KINX
OK Vance AFB KVNX
KS Dodge City KDDC
KS Goodland KGLD
KS Topeka KTWX
KS Wichita KICT
NE Grand Island/Hastings KUEX
NE North Platte KLNX
NE Omaha KOAX
SD Aberdeen KABR
SD Rapid City KUDX
SD Sioux Falls KFSD
ND Bismarck KBIS
ND Grand Forks KMVX
ND Minot AFB KMBX
MT Billings KBLX
MT Glasgow KGGW
MT Great Falls KTFX
MT Missoula KMSX
WY Cheyenne KCYS
WY Riverton KRIW
CO Denver KFTG
CO Grand Junction KGJX
CO Pueblo KPUX
NM Albuquerque KABX
NM Cannon AFB KFDX
NM Holloman AFB KHDX
AZ Flagstaff KFSX
AZ Phoenix KIWA
AZ Tucson KEMX
AZ Yuma KYUX
UT Cedar City KICX
UT Salt Lake City KMTX
ID Boise KCBX
ID Pocatello/Idaho Falls KSFX
NV Elko KLRX
NV Las Vegas KESX
NV Reno KRGX
CA Beale AFB KBBX
CA Edwards AFB KEYX
CA Eureka KBHX
CA Los Angeles KVTX
CA Sacramento KDAX
CA San Diego KNKX
CA San Francisco KMUX
CA San Joaquin Valley KHNX
CA Santa Ana Mountains KSOX
CA Vandenberg AFB KVBX
HI Kauai PHKI
HI Kohala PHKM
HI Molokai PHMO
HI South Shore PHWA
OR Medford KMAX
OR Pendleton KPDT
OR Portland KRTX
WA Seattle/Tacoma KATX
WA Spokane KOTX
AK Bethel PABC
AK Fairbanks/Pedro Dome PAPD
AK Kenai PAHG
AK King Salmon PAKC
AK Middleton Island PAIH
AK Nome PAEC
AK Sitka/Biorka Island PACG
GU Andersen AFB PGUA


See also



Bibliography

  • David Atlas, Radar in Meteorology: Battan Memorial and 40th Anniversary Radar Meteorology Conference, published by the American Meteorological Society, Bostonmarker, 1990, 806 pages, ISBN 0-933876-86-6, AMS Code RADMET.


References

  1. WSR-88D Radar, Tornado Warnings and Tornado Casualties.
  2. O'Bannon, Tim 1995. Anomalous WSR-88D Wind Profiles – Migrating Birds? American Meteorological Society 27th Conference on Radar Meteorology Preprints: 663–665
  3. Build10FAQ
  4. NEXRAD Product Improvement – Current Status of WSR-88D Open Radar Data Acquisition (ORDA) Program and Plans For The Future
  5. Polarimetric Radar Page
  6. Weather Research: Weather Radar
  7. Airline flights get less turbulent – EE Times, Sep 11, 2007


External links

Theory of Doppler Weather Radar
Real time data
Research



Embed code:
Advertisements






Got something to say? Make a comment.
Your name
Your email address
Message