NWS ILX - Dual Polarization Radar Installation

Photo Courtesy of Reid Wolcott	NWS Central Illinois WSR-88D to Receive Dual Polarization Upgrade
During a two-week period, beginning October 1, 2012, the Doppler radar at your National Weather Service Forecast Office will undergo an upgrade to incorporate new technology. For these two weeks, radar data will be unavailable from NWS Central Illinois! Surrounding radars include: Quad Cities, IA, Milwaukee, WI, Chicago, IL, Indianapolis, IN, Evansville, IN, Paducah, KY, and St. Louis, MO. This much anticipated upgrade is part of the NWS vision to build a Weather-Ready Nation to better protect lives and livelihoods. This exciting upgrade will incorporate a new technology called dual-polarization, or dual-pol. This new technology will result in 14 new radar products that will enable us to continue providing our suite of high quality products and services to the public. This new technology and data will primarily help forecasters identify the type of precipitation that is falling as well as improve rainfall estimates

Current NWS Doppler radars transmit and receive pulses of radio waves in 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. Therefore, the radar measures 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 variety of 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, such as chaff, ground clutter, and smoke plumes from wildfires that are not uncommonly detected by weather radar systems such as WSR-88D.
Current NWS Doppler Radar	Dual-Pol Radar


Better estimation of total precipitation amounts Better estimation of the size distribution of hydrometeors (raindrops, snowflakes, hailstones, drizzle) Much improved ability to identify areas of extremely heavy rainfall that are closely linked with flash floods Improved detection and mitigation of non-weather related radar echoes (chaff, smoke plumes, ground clutter) Easier identification of the melting layer (helpful for identifying snow levels in higher terrain) Improved ability to classify precipitation type The full benefit of dual-pol radar, however, will not be fully realized until NWS forecasters and research meteorologists develop real-time expertise.

A radio wave is a set of oscillating electric and magnetic fields, oriented 90 degrees to each other. Polarization of the wave is the direction, or orientation, of the electric field. Horizontal Polarization
	The electric field is oriented horizontally, along the x-axis (blue). The magnetic field is oriented vertically along the y-axis (white).
Vertical Polarization
	The electric field is oriented vertically, along the y-axis (orange). The magnetic field is oriented horizontally along the x-axis (white).

Dual-Polarization Training for NWS Partners National Severe Storms Laboratory Dual-Pol Page National Severe Storms Laboratory Dual-Pol FAQ Page

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