The polarimetric upgrade to the National Weather Service's WSR-88D network: An overview of data and products available to operational forecasters

Over the past decade, a prototype polarimetric WSR-88D radar has been developed and tested at the NOAA/National Severe Storms Laboratory in central Oklahoma. Polarimetric radars transmit and receive both horizontal and vertical polarizations. By computing ratios and correlation coefficients of reflected horizontal and vertical power, as well as examining shifts in the received horizontal and vertical phase, more information than previously available is obtained on the size, shape, and ice density of cloud and precipitation particles, leading to improved algorithms to estimate the precipitation type and rainfall accumulation.

With the upgrade of the NWS WSR-88D radar network to include polarimetric technology, which is scheduled to begin in the Spring of 2011, forecasters will be able to clearly identify precipitation type like never before. Some of the many benefits provided by polarimetric radar include: improved rainfall accumulation accuracy, better rain/hail discrimination, increased confidence in precipitation type in winter storms, and better overall data quality through the elimination of non-meteorological targets. This talk will provide a brief introduction to polarimetric radars, discuss the new “raw” data variables and explain what each tells us about the precipitation microphysics, and provide an overview of the new products that will be available to operational forecasters.