National Academies Press: OpenBook
« Previous: Appendix A: Origin of the Study
Suggested Citation:"Appendix B: Characteristics of the NEXRAD Radar." National Research Council. 2005. Flash Flood Forecasting Over Complex Terrain: With an Assessment of the Sulphur Mountain NEXRAD in Southern California. Washington, DC: The National Academies Press. doi: 10.17226/11128.
×

Appendix B
Characteristics of the NEXRAD Radar

Parameter or Feature

Value or Description

Radar System

 

Range of Observation

 

Reflectivity

460 km

Velocity

230 km

Angular Coverage

 

Azimuth

Full circle or sector

Elevation

Operational limits; –1° to +20°

Antenna

 

Type

S-band, center-fed, parabolic dish

Reflector aperture

8.54-m (28-foot) diameter; circular

Beamwidth (one-way, 3 dB)

0.96° at 2.7 GHz; 0.88° at 3.0 GHz

Gain

45.8 dB at 2.85 GHz (midband)

Polarization

Linear horizontal

First side-lobe level

–29 dB

Steerability

360° azimuth; –1° to +45° elevation

Mechanical limits

–1° to +60°

Rotation rate

30° s –1 (azimuth and elevation)

Angular acceleration

15° s –2 (azimuth and elevation)

Pointing accuracy

±0.2°

Radome

 

Type

Fiberglass skin foam sandwich

Diameter

11.89 m (39 feet.)

RF Loss (two-way)

0.3 ± 0.06 dB over 2.7–3.0-GHz band

Transmitter

 

Type

Master Oscillator Power Amplifier (MOPA)

Frequency range

2.7–3.0 GHz

Peak power output (nominal)

500 kW into antenna

Pulsewidth (nominal)

1.57 μs (short pulse); 4.5 μs (long pulse) ± 4%

RF duty cycle (maximum)

0.002

Suggested Citation:"Appendix B: Characteristics of the NEXRAD Radar." National Research Council. 2005. Flash Flood Forecasting Over Complex Terrain: With an Assessment of the Sulphur Mountain NEXRAD in Southern California. Washington, DC: The National Academies Press. doi: 10.17226/11128.
×

Pulse Repetition Frequency

 

Long pulse

322–422 Hz ± 1.7%

Short pulse

322–1282 Hz ± 1.7%

Waveform types

Contiguous and batch (phase-coded build 8.0)

Receiver

 

Type

Linear

Tunability (frequency range)

2.7–3.0 GHz

Bandwidth (3 dB)

0.63 MHz (short pulse); 0.22 MHz (long pulse)

Phase control

Selectable

Receiver channels

Linear output I/Q

Dynamic range

95 dB max; 93 dB at 1-dB compression

Minimum detectable signal

–113 dBm (ORDA)

Noise temperature

450 K (ORDA)

Intermediate frequency

57.6 MHz

Sampling rate

600 kHz (This remains the same for the I/Q samples; IF samples will be at 72 MHz)

Signal Processor

 

Type

Programmable

Parameters derived

Reflectivity; mean radial velocity; Doppler spectral width

Algorithms (respective)

Power averaging; pulse-pair; single-lag correlation

Accuracy (Standard Deviation)

 

Reflectivity

<1 dB

Velocity and spectrum width

<1 m s1

Number of Pulses Averaged

 

Reflectivity

6–64

Velocity and spectrum width

40–200

Range Resolution

 

Reflectivity

1 km

Velocity and spectrum width

0.25 km

Azimuth Resolution

 

Reflectivity

Velocity and spectrum width

Clutter canceller

Gaussian Model Adaptive Processing Filter, Spectral Domain

Clutter suppression

30–50 dB max

Radar Product Generator (RPG)

RPG processor

64-bit reduced instruction set (RISC) digital computer

Shared memory

512-MB semiconductor memory

Wide-band communication

1.544 Mbit s–1 data rate

Narrow-band communication

Up to 13 of 14,400/4,800 bit s–1 4-wire

(1 may be 33,600 bit s–1 capable)

8 of 14,400/4,800 bit s–1 2-wire

Up to 9 Wide Area Network (WAN) connections

RPG Graphic Display Processor

 

Principal user processor (PUP)

64-bit RISC digital computer

Suggested Citation:"Appendix B: Characteristics of the NEXRAD Radar." National Research Council. 2005. Flash Flood Forecasting Over Complex Terrain: With an Assessment of the Sulphur Mountain NEXRAD in Southern California. Washington, DC: The National Academies Press. doi: 10.17226/11128.
×

Communications

14,400/4,800 bit s–1; 2- and 4-wire (maximum: 28 lines)

Video

Color, with split-screen and zoom features

Mass

storage Up to two 40-GB disks

Other

National Climatic Data Center (NCDC)

National archive for NEXRAD data and other meteorological and climatological data.

Level II archive

Network interface located at the RPG. Digital base data are output from the Base Data Dissemination System (BDDS), which includes base reflectivity, mean radial velocity, and spectrum width. Data are sent electronically to the NCDC for permanent storage. (Completed nationwide in September 2004)

Level III archive

Interface is located at the RPG. A set of predetermined products defined in FMH-11 Part A is sent electronically to NCDC for permanent storage. (Completed nationwide in September 2004)

National Weather Radar Network

Consists of WSR-88D sites dispersed throughout the conterminous United States (CONUS) plus Department of Defense sites or non-CONUS Department of Transportation sites.

Suggested Citation:"Appendix B: Characteristics of the NEXRAD Radar." National Research Council. 2005. Flash Flood Forecasting Over Complex Terrain: With an Assessment of the Sulphur Mountain NEXRAD in Southern California. Washington, DC: The National Academies Press. doi: 10.17226/11128.
×
Page 172
Suggested Citation:"Appendix B: Characteristics of the NEXRAD Radar." National Research Council. 2005. Flash Flood Forecasting Over Complex Terrain: With an Assessment of the Sulphur Mountain NEXRAD in Southern California. Washington, DC: The National Academies Press. doi: 10.17226/11128.
×
Page 173
Suggested Citation:"Appendix B: Characteristics of the NEXRAD Radar." National Research Council. 2005. Flash Flood Forecasting Over Complex Terrain: With an Assessment of the Sulphur Mountain NEXRAD in Southern California. Washington, DC: The National Academies Press. doi: 10.17226/11128.
×
Page 174
Next: Appendix C: Chronology of the Siting of the Sulphur Mountain NEXRAD »
Flash Flood Forecasting Over Complex Terrain: With an Assessment of the Sulphur Mountain NEXRAD in Southern California Get This Book
×
Buy Paperback | $62.00 Buy Ebook | $49.99
MyNAP members save 10% online.
Login or Register to save!
Download Free PDF

The nation's network of more than 130 Next Generation Radars (NEXRADs) is used to detect wind and precipitation to help National Weather Service forecasters monitor and predict flash floods and other storms. This book assesses the performance of the Sulphur Mountain NEXRAD in Southern California, which has been scrutinized for its ability to detect precipitation in the atmosphere below 6000 feet. The book finds that the Sulphur Mountain NEXRAD provides crucial coverage of the lower atmosphere and is appropriately situated to assist the Los Angeles-Oxnard National Weather Service Forecast Office in successfully forecasting and warning of flash floods. The book concludes that, in general, NEXRAD technology is effective in mountainous terrain but can be improved.

  1. ×

    Welcome to OpenBook!

    You're looking at OpenBook, NAP.edu's online reading room since 1999. Based on feedback from you, our users, we've made some improvements that make it easier than ever to read thousands of publications on our website.

    Do you want to take a quick tour of the OpenBook's features?

    No Thanks Take a Tour »
  2. ×

    Show this book's table of contents, where you can jump to any chapter by name.

    « Back Next »
  3. ×

    ...or use these buttons to go back to the previous chapter or skip to the next one.

    « Back Next »
  4. ×

    Jump up to the previous page or down to the next one. Also, you can type in a page number and press Enter to go directly to that page in the book.

    « Back Next »
  5. ×

    Switch between the Original Pages, where you can read the report as it appeared in print, and Text Pages for the web version, where you can highlight and search the text.

    « Back Next »
  6. ×

    To search the entire text of this book, type in your search term here and press Enter.

    « Back Next »
  7. ×

    Share a link to this book page on your preferred social network or via email.

    « Back Next »
  8. ×

    View our suggested citation for this chapter.

    « Back Next »
  9. ×

    Ready to take your reading offline? Click here to buy this book in print or download it as a free PDF, if available.

    « Back Next »
Stay Connected!