The VPR is an X-band Doppler radar, developed at McGill University, which measures reflectivity, Doppler velocity, and the distribution of hydrometeor fall speeds. With these variables, collected at 10-minute averages in the horizontal and 75m resolution in the vertical, a computer can be programmed to identify the melting layer, types of precipitation, and location of precipitation. Further analysis of the data provides information about potentially dangerous icing regions. From the distribution of fall speeds, one can separate out modes, or peaks in the power returned, and the existence of more than one mode is a good indication of a hidden type of hydrometeors, such as SLW. In addition, a relationship between reflectivity and Doppler velocity provides information on the type of hydrometeor and warns of conditions like riming, an excellent indication that there is SLW in the region.
When combined into one system and run continuously over time, the 5 algorithms in this study will be able to provide a timely, affordable, and valuable warming as to the level and extent of icing conditions occurring in the airport region. When considering the value of the information provided by the VPR, it is important to note that it costs only a tiny fraction of typical scanning radar.