The WSR88D

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The WSR-88D

• Weather Surveillance Radar

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WSR-88D Components
Steve
AWIPS Advanced Weather Interactive Processing
System
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Inside the Dome
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How Does It Work?

• NEXRAD (Next Generation Radar) obtains weather
  information based upon returned energy.
• The radar emits a burst of energy (green). If the
  energy strikes an object (rain, bug, bird, etc),
  the energy is scattered in all directions (blue).
• A small fraction of that scattered energy is
  directed back toward the radar.

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How Does It Work?

• This reflected signal is then received by the
  radar during its listening period.
• Computers analyze the strength of the returned
  pulse, time it took to travel to the object and
  back, and phase shift of the pulse.
• This process of emitting a signal, listening for
  any returned signal, then emitting the next
  signal, takes place very fast, up to around 1300
  times each second.

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Did You Know?

• NEXRAD spends the vast amount of time "listening"
  for returning signals it sent.
• When the time of all the pulses each hour are
  totaled (the time the radar is actually
  transmitting), the radar is "on" for about 7
  seconds each hour.
• The remaining 59 minutes and 53 seconds are spent
  listening for any returned signals.

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What are the different types of radar images?

• Base Reflectivity
• Composite Reflectivity
• Velocity
• Storm Relative Velocity
• One-hour Precipitation
• Storm Total Precipitation

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Base Reflectivity
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Comparing Base and Composite Reflectivity
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Velocity
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Precipitation
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Scan Strategies

• Clear Air Mode
• Precipitation Mode

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Clear Air Mode

• Most sensitive mode of operation
• Slowest antenna rotation rate
• Mostly detects airborne dust and particulate
  matter
• Occasionally used for detection of light snow

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Precipitation Mode

• Less sensitive (plenty of returning signals)
• Need to see higher elevation angles (especially
  for severe storms)
• Helps to analyze the vertical structure of the
  storms

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Coming Soon

• Dual Polarization Doppler Radar
• Sends out a horizontal and a vertical pulse
• Able to identify sizes and shapes of targets
• Also able to detect fall rates, more importantly,
  changes in fall rates

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Contact Info

• john.juskie_at_noaa.gov
• steve.goldstein_at_noaa.gov