The organization that lead the development of Doppler weather radar is working to make it better. The Commerce Department's National Oceanic and Atmospheric Administration's National Severe Storms Laboratory is working on an improvement of the Doppler technology and will soon test a completely new type of radar. The new technology is expected to lead to improved tornado and flash flood warnings in the future.

The National Oceanic and Atmospheric Administration's National Severe Storms Laboratory is developing polarimetric technology that can be added to the current WSR-88D Doppler weather radars used by the National Weather Service throughout the nation. The dual-polarization radar provides improved estimates of rain and snow rates and amounts, better detection of the location of large hail in summer storms, and improved identification of rain and snow transition regions in winter storms, said NSSL Director James Kimpel. A test of polarimetric technology in a forecast setting will take place this spring in the National Weather Service Forecast Office in Norman, Okla.

In addition, NSSL researchers will soon begin adapting SPY-1 radar technology, developed by Lockheed Martin to support tactical operations aboard Navy ships, for use in spotting severe weather. Early tests of this phased array radar system have proved promising, Kimpel said.

"These projects provide the opportunity to continue NSSL's leadership in the research and development of future generations of weather radar," Kimpel said. "Ultimately, this research will lead to better forecasts and improved severe weather warnings."

Norman is already known as the center for weather radar research and development in the nation. Nearly 30 years ago, researchers there began developing what became the WSR-88D, known as NEXRAD, a system of 158 Doppler radars deployed across the United States and around the world.

Most weather radars, such as the current technology in the WSR-88D, transmit radio wave pulses that have a horizontal orientation. Polarimetric radars gather more information by transmitting radio wave pulses that have both horizontal and vertical orientations. The horizontal pulses essentially give a measure of the horizontal dimension of cloud particles (cloud water and cloud ice) and precipitation particles (snow, ice pellets, hail, and rain), while the vertical pulses essentially give a measure of the vertical dimension. Since the power returned to the radar is a complicated function of each particle's size, shape and ice density, the information will permit a detailed mapping of cloud composition. This information can be incorporated into short term computer models, leading to better forecasts.

In the next two years, a National Weather Radar Testbed will be established at NSSL, which will provide the first phased array radar facility available on a full-time basis to the radar meteorological research community. Using electronically controlled beams, phased array radar reduces the scan time of severe weather from six minutes for current WSR-88D technology to only one minute, producing quicker updates of data and thereby potentially increasing the average lead time for tornado warnings.

The new system will be able to scan the atmosphere with more detail at lower elevations than current radar allows. It will also be able to re-scan areas of severe weather very quickly, improving forecasters' warning capability. In addition, the new technology will gather storm information not currently available, such as rapid changes in wind fields, to provide forecasters with better conceptual storm models and to initialize stormscale forecast models.

A unique federal, private, state and academic partnership will develop the phased array technology. Participants include the National Severe Storms Laboratory, Lockheed Martin, U.S. Navy, National Weather Service, University of Oklahoma's Department of Meteorology and College of Engineering and the Federal Aviation Administration.

Researchers have been developing dual polarization radar for more than 20 years and expect the technology to be available for installation into the national radar network in five to 10 years. The phased array radar project – including research, development, technology transfer and deployment throughout the U.S. – is expected to take 10 to 15 years at an initial cost of approximately $25 million for the facility in Norman.

More information is available online about dual polarization radar at http://www.nssl.noaa.gov/dualpol
and about phased-array radar at http://www.nssl.noaa.gov/par.