Dual Polarization Radar

Dual-polarization, or dual-pol, is part of the NWS vision to build a weather-ready nation to better protect lives and livelihoods. This new technology provides 14 new radar products that will support our mission to serve our partners and customers in Central Alabama.

Dual-polarimetric radar transmits and receives pulses in both a horizontal and vertical orientation. As a result, the returning frequencies provide measurements of the horizontal and vertical dimensions of targets, supplying forecasters with better estimates of the size, shape, and variety of targets.

Old NWS WSR-88D radar	Dual-polarimetric radar

Benefits of Dual-Pol

• Improved accuracy of precipitation estimates, leading to better flash flood detection
• Ability to discern between heavy rain, hail, snow, and sleet
• 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)

The base radar products that have been available to users are base reflectivity, base velocity, and spectrum width. After the Dual-Pol upgrade, three new base products will be available: differential reflectivity (ZDR), correlation coefficient (CC), and specific differential phase (KDP). In addition to these three base products, there are several derived products. These include a melting layer (ML) product, a hydrometeor classification algorithm (HCA) product, and eight new precipitation products. Mouse-over the labels below to view examples of four of these new products. Images courtesy of the Warning Decision Training Branch.