Joint Polarization Experiment
The Joint Polarization Experiment (JPOLE) was a test for evaluating the performance of the WSR-88D in order to modify it to include dual polarization. This program was a joint project of the National Weather Service (NWS), the Federal Aviation Administration (FAA), and the US Air Force Meteorological Agency (AFWA), which took place from 2000-2004. It has resulted in the upgrading of the entire meteorological radar network in the United States by adding dual polarization to better determine the type of hydrometeor, and quantities that have fallen. History. During the years preceding JPOLE, the National Center for  Atmospheric Research (NCAR) was among the first centers in the field to utilize dual polarization for a weather radar, with staff Dusan S. Zrnic and Alexander V. Ryzhkov. In July 2000, the first planning meeting for JPOLE was held at the National Severe Storms Laboratory (NSSL), and it was determined that the project would take place in two stages: Description. JPOLE was introduced using a testbed NEXRAD mounted in Norman, Oklahoma, on the grounds of the NSSL. The signal from its transmitter was split in two to obtain a conventional horizontal polarization and a vertical polarization. The signals were sent  to the antenna by two waveguides and could simultaneously transmit the two signals and furthermore receive the echoes returned by the precipitation in the emitted or orthogonal planes. In general, most hydrometeors have a larger axis in the horizontal (for example, drops of rain become oblates when falling because of the resistance of the air). Because of this, the dipolar axis of the water molecules therefore tends to align in the horizontal and, as such, the radar beam will generally be horizontally polarized to take advantage of maximum return properties. If we send at the same time a pulse with  vertical polarization and another with horizontal polarization, we can note a difference of several characteristics between these returns: