Dual Polarization Upgrade to the Wichita (KICT) Radar
July 5-17th, 2011
The National Weather Service office in Wichita, Kansas is pleased to announce that the much-anticipated installation process of the Dual-Polarization Radar upgrade to the KICT WSR-88D will occur between July 5th and July 17th 2011. The Wichita Forecast Office, will be the third WSR-88D to receive this important technology as one of the Beta Test sites. The upgrade has already been completed at the Phoenix, AZ (KIWA) and Morehead City, NC (KMHX) radars. Pittsburgh, PA (KPBZ) will receive the upgrade at the same time as Wichita. This upgrade will greatly expand the amount of data types and radar products available to users. This new technology and data will, among other things, help forecasters identify the type of precipitation that is falling as well as improve rainfall estimates. It is important to note that during the entire time of installation, the radar will be unavailable, however surrounding radar sites will still be operational.
What is Doppler Radar?
Conventional Doppler radars transmit bursts of radio waves, called pulses, in a single, horizontal orientation, or polarization. The pulses bounce off meteorological (i.e. clouds, snow, ice pellets, hail and rain drops) and non-meteorological (i.e. birds, insects, ground clutter, including wind farms etc.) particles in the atmosphere, and are reflected back to and received by the radar dish. After computer processing, the returned signals are converted into usable data regarding the horizontal properties of the particles encountered, including their dimensions, direction and speed of movement. For instance, the distance from the radar to the target is calculated from the amount of time that lapses from the initiation of the pulse, to the detection of the return signal. The radar reflectivity you see on a radar image is actually the “reflected” pulse energy that is received by the radar.
What is Dual Polarization Radar?
Dual-polarization, or Polarimetric, radars transmit and receive both horizontally and vertically oriented radio wave pulses, typically done by alternating between horizontal and vertical polarization with each pulse. This therefore allows the radar to collect data with information on the horizontal and vertical properties of the targets. Being able to analyze targets in this manner is expected to result in significant improvements in the estimation of precipitation rates, the ability to discriminate different precipitation types (i.e. rain vs. hail, mixed precipitation types in winter storms), and the identification of non-meteorological returns. As an added example, for aviation concerns, with polarimetric radar, forecasters will be able to better discern areas of icing and other hazards such as birds. All these improvements will aid forecasters in the warning decision process, helping the public make better decisions about their safety and protecting their property.
What New Data will be Available?
The basic radar products that have been available to users are Z, reflectivity (base and composite), V, mean radial velocity (base and storm relative), and SW, spectrum width. Three new products that will become available after the upgrade are ZDR, differential Reflectivity, CC, correlation coefficient, and KDP, specific differential phase. Below is an example of Differential Reflectivity on the left, versus reflectivity on the right. The area circled on both images is a hail core in a thunderstorm, demonstrating how Differential Reflectivity can allow for better discrimination of hail from just heavy rainfall. Along with the three base products above, included among three new derived products will be Quantitative Precipitation Estimation (QPE), which will allow for the estimation of instantaneous rainfall rate. Currently, only 1-hour radar-based rainfall rate estimations are available.
If you have any questions please contact Wichita Webmaster.