Doppler radar technology has evolved, thanks to the dedicated work of NOAA researchers who developed dual polarization technology, or dual-pol (pronounced “dual pole”).  This new technology helps forecasters distinguish between rain, snow, hail, and other flying objects that muddy the radar picture. The dual-pol upgrade includes new software and a hardware attachment to the radar dish that sends and receives both horizontal and vertical pulses, providing a much more informative two-dimensional picture. The original Doppler radar only has a one-dimensional view.

NOAA’s National Weather Service is half-way through upgrading its network of 160 Doppler radars throughout the nation with this new technology. The dual-pol upgrade is the most significant enhancement ever made to the nation’s radar network since Doppler radar was first installed in the early 1990s. Providing better information about the type of precipitation in the atmosphere and its intensity, size and location, dual-pol radars will increase the accuracy of forecasts and allow for more accurate and timely warnings, giving the public better information to protect their lives and property.

from http://www.nws.noaa.gov/com/weatherreadynation/news/080212_dual.html