Picture of WSR-88D Radar

Photo Courtesy of Reid Wolcott


NWS Topeka WSR-88D to Receive Dual Polarization Upgrade

During a two-week period, beginning January 17, 2012, the Doppler radar at your National Weather Service Forecast Office will undergo an upgrade to incorporate new technology. For these two weeks, radar data will be unavailable from NWS Topeka! Surrounding radars include: Hastings, NE, Omaha, NE, Kansas City, MO, Springfield, MO, and  Wichita, KS.

This much anticipated upgrade is part of the NWS vision to build a Weather-Ready Nation to better protect lives and livelihoods. This exciting upgrade will incorporate a new technology called dual-polarization, or dual-pol. This new technology will improve our ability to determine the type of precipitation that is falling (for example rain versus hail), as well as improve radar estimates of how much precipitation has fallen. This addition of 14 new radar products will also enhance our suite of high quality products and services currently available to the public.

Why Upgrade to Dual-Pol?
Current NWS Doppler radars transmit and receive pulses of radio waves in a horizontal orientation. As a result, the radar only measures the horizontal dimensions of targets (e.g. cloud and precipitation droplets). Dual-polarimetric radar transmits and receives pulses in both a horizontal and vertical orientation. Therefore, the radar measures both the horizontal and vertical dimensions of targets. Since the radar receives energy from horizontal and vertical pulses, we can obtain better estimates of the size, shape, and variety of targets. It is expected that this will result in significant improvements in the estimation of precipitation rates, the ability to discriminate between precipitation types (e.g. hail vs. rain), and the identification of non-meteorological returns, such as chaff, ground clutter, and smoke plumes from wildfires that are not uncommonly detected by weather radar systems such as WSR-88D.
Current NWS Doppler Radar
Dual-Pol Radar
The Benefits of Dual-Pol
  • Better estimation of total precipitation amounts
  • Better estimation of the size distribution of hydrometeors (raindrops, snowflakes, hailstones, drizzle)
  • Much improved ability to identify areas of extremely heavy rainfall that are closely linked with flash floods
  • Improved detection and mitigation of non-weather related radar echoes (chaff, smoke plumes, ground clutter)
  • Easier identification of the melting layer (helpful for identifying snow levels in higher terrain)
  • Improved ability to classify precipitation type

By distributing dual pol to local radars, meteorologists will be able to analyze the benefits in real time and conduct research projects on the incoming data.

What is Polarization?

A radio wave is a set of oscillating electric and magnetic fields, oriented 90 degrees to each other. Polarization of the wave is the direction, or orientation, of the electric field.

Horizontal Polarization

Horizontal Polarization Graph

The electric field is oriented horizontally, along the x-axis (blue). The magnetic field is oriented vertically along the y-axis (white).

Vertical Polarization

Vertical Polarization Graph

The electric field is oriented vertically, along the y-axis (orange). The magnetic field is oriented horizontally along the x-axis (white).

Want to Learn More?

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  • National Weather Service
  • Topeka, KS Weather Forecast Office
  • 1116 NE Strait Avenue
  • Topeka, KS 66616-1698
  • 785-234-2592
  • Page Author: TOP Webmaster
  • Web Master's E-mail: w-top.webmaster@noaa.gov
  • Page last modified: 19-Oct-2011 7:38 PM UTC


USA.gov is the U.S. government's official web portal to all federal, state and local government web resources and services.