Key West WSR-88D Dual Polarization Upgrade
January 16 - January 29, 2012

The dual-polarization radar upgrade to the KBYX WSR-88D will begin on Monday, January 16th and will last approximately two weeks.  During this installation period, the KBYX radar will be unavailable.  However, our neighboring WSR-88D radar in Miami will be operational.

This long awaited upgrade will incorporate new technology called dual-polarization, or dual-pol, which is part of the NWS vision to build a weather-ready nation to better protect life and livelihood.  This new technology will result in 14 radar products to augment our suite of high quality products and services.  The main purpose of this technology will be to provide assistance to forecasters in the identification of precipitation type as well as the improvement in the estimation of rainfall amounts.

We strongly encourage users of these new products to complete a series of online training modules that were recorded by the Warning Decision Training Branch (WDTB).  Modules are available for non-NWS meteorologists and non-meteorologists through this website.

What is Dual-Pol?

The current doppler radars transmit and receive pulses of radio waves in a horizontal orientation.  As a result, the radar only samples the horizontal dimensions of targets (e.g. cloud and precipitation droplets).  Dual-polarimetric radar transmits and receives pulses in both the horizontal and vertical orientation.  Therefore, the radar samples 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 type of reflectivity 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.

 Current NWS doppler radar
 Dual-pol radar
Current NWS doppler radar Dual-polarimetric radar

Benefits of Dual-Pol
  • Improved accuracy of precipitation estimates, leading to better flood detection
  • Ability to discern between heavy rain and hail
  • Improved detection of non-meteorological echoes (e.g. ground clutter, chaff, anomalous propagation, birds, and tornado debris)
  • Detection of aircraft icing conditions
  • Identification of the melting layer (e.g. bright band)

Dual-Pol will not improve tornado lead times or be able to provide exact precipitation type on the ground.

Dual-Pol Products & Applications
The base radar products that have been available to users are base reflectivity, base velocity, and spectrum width.  Three new base products will be available after the dual-pol upgrade, including differential reflectivity (ZDR), correlation coefficient (CC), and specific differential phase (KDP).  In addition to these three new base products, there will be several dervied products including a melting layer (ML), a hydrometeor classification algorithm (HCA), and eight new precipitation products.  Hover your mouse over the labels below to see examples of some of the new products.  Images courtesy of the Warning Decision Training Branch.

Differential Reflectivity

Using differential reflectivity to identify a hail core
Using correlation coefficient to identify the melting layer and thunderstorm updrafts
Using specific differential phase to identify the melting layer and thunderstorm updrafts
Images courtesy of WDTB

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