The National Weather Service in Wilmington Ohio completed the dual-polarization radar upgrade between August 23 and August 28, 2012. The KILN radar has returned to service, and data is available through our usual means of dissemination.
What will dual-polarization do?
Current NWS radars provide information on precipitation intensity and movement. Dual-polarization technology adds the ability to sense the size and shape of objects in the atmosphere. This will enable meteorologists to make numerous advances in forecasting and warning capabilities:
Improved accuracy in identifying precipitation types. This will lead to more accurate winter weather forecasts, especially during times of mixed and icy precipitation.
Improved precipitation estimates. This will lead to more accurate river forecasts and flash flood warnings.
Improved detection of non-precipitation targets. This will allow forecasters to focus on real precipitation radar targets.
Improved hail detection. The new radar products will lead to increased confidence in the presence and size of hail in strong to severe thunderstorms.
The ability to detect lofted tornado debris. Although this will not directly lead to improvements in tornado warnings, it will provide higher confidence of a tornado's presence and track when significant damage is occurring. This could be especially benefical at night, when
tornadoes are difficult to see. A caveat though; tornadoes will need to be close to the radar to sample the lofted debris, or a far tornado will need to be strong to be able to lift
debris to the altitude that the radar will be sampling it.
How does it work?
Conventional Doppler radar transmits and receives horizontally polarized radio wave pulses. Thus, the radar is only able to measure the horizontal dimension of atmospheric targets.
Dual-polarization Doppler radar transmits and receives pulses that are polarized both horizontally and vertically. Thus, the radar is able to measure the horizontal and vertical dimensions of atmospheric targets.
By comparing the power returned to the radar from the differing horizontal and vertical pulses, a great deal of information can be generated with respect to the size and shape of targets in the atmosphere.
Animation of Single Vs. Dual Polarization
Current NWS Doppler Radar
Where can I learn more?
The NWS Radar Operations Center published a FAQ with more information on the nationwide dual-polarization radar upgrade.