WSR-88D Dual-Polarization Upgrade
 
*Update* Dual-polarization upgrades at the Cannon Air Force Base radar (KFDX)  Albuquerque radar (KABX) are complete as of Saturday, May 5, 2012. KABX radar
 
What does dual-polarization mean?
National Weather Service legacy Doppler radars transmit and receive horizontal radio waves only, which means current technology can only measure the horizontal dimension of precipitation particles. Radars with the dual-polarization upgrade transmit and receive both horizontal and vertical radio waves, thereby being able to measure both the horizontal and vertical dimensions of precipitation particles.
 
88D Simulation Dual Pol Simulation
Current Radar Technology Dual-Polarization Technology
   
What are the benefits of dual-polarization?
Dual-polarization technology will allow forecasters to better discern the size, shape and variety of not only precipitation particles, but non-precipitation particles as well (i.e. birds, bugs, debris).  Forecasters will even be able to better distinguish precipitation type (i.e. hail, rain, snow).  This will lead to improved precipitation estimates, and ultimately lead to better flash flood warnings and increase forecaster confidence when issuing severe thunderstorm and tornado warnings. Note that areas currently suffering from beam blockage will remain so.
 
What are the new dual-pol products?
The dual-pol products available include:
  • Differential Reflectivity (ZDR) - a ratio of the reflected horizontal and vertical power returns. Differential reflectivity is a good indicator of the size and shape of the target.
  • Correlation Coefficient (CC) - A correlation between the reflected horizontal and vertical power returns. Correlation coefficient is a good indicator of hydrometeor diversity.
  • Specific Differential Phase (KDP) - A comparison of the returned phase difference between the horizontal and vertical pulses.  Specific differential phase is a good indicator of rain rate.
  • Hydrometeor Classification (HC) - An algorithm that determines the most likely echo type by utilizing reflectivity, velocity, ZDR, CC, and KDP values.
 
There will also be a new suite of precipitation products (8 in all) that mirror the legacy products, but utilize the above data.
 
How can I learn more?
Anyone using dual-polarization data is strongly encouraged to complete a series of training modules developed by the Warning Decision Training Branch.  Modules are available for both meteorologists and non-meteorologists here.
 
Can I see an example?
Sure!  Below are two examples highlighting the new products.  The first is a winter weather example from our neighboring office in Amarillo, TX.  The second example is a spring tornado case from the office in Norman, OK.  Use the tabs at the top of the images to cycle through the various dual-pol products. Though reflectivity is not a new product, it is presented for your reference.
 

Reflectivity

 
 

Reflectivity

 

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