What is Dual-Pol?

How it Works
Prior to the dual polarization upgrade, the WSR-88D transmits and receives pulses of radio waves in only 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. 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. The images below illustrate the difference between non-polarimetric radar and polarimetric radar.

Before Dual-Pol Upgrade

After Dual-Pol Upgrade

Educational Videos

Here are some quick educational videos from NOAA Weather Partners.

This first video features Paul Schlatter explaining the difference between conventional Doppler radar and dual-polarized radar.

This next video takes a more comical approach to showing some of the benefits of the dual-pol upgrade.

Benefits

Here are some of the benefits from the upgrade to dual-pol radar:

Ability to detect tornadic debris, providing additional confirmation of dangerous storms.
Ability to discern between precipitation and non-meteorological echoes such as ground clutter, chaff, anomalous propagation, and birds.
Improved ability to identify areas of heavy rainfall. Also, better estimation of total precipitation, leading to better flash flood detection.
Ability to distinguish between different precipitation types.
Easier identification of the melting layer.

For some real-life examples of ways that dual-pol technology has helped forecasters, check out the applications page.