Simulation of X-band radar observation of precipitation from S-band measurements

Monitoring of precipitation using high frequency radar systems such as X-band is becoming increasingly popular due to their lower cost compared to their counterpart at S-band. Meteorological radar systems operating at S-band frequencies are not affected by attenuation due to precipitation. The S-band radar systems are typically expensive with large antennas, and high power transmitters. Recently, network of meteorological radar systems at higher frequencies such as X band are being pursued, especially for low cost and targeted applications, such as coverage over a city or a small basin. Attenuation correction of the signal returns from these radars is important for quantitative applications. In order to design the radar systems as well as evaluate algorithm development, it is useful to have simultaneous X-band observation with and without the impact of path attenuation. The only way to collect such data is from dual frequency radar system with matched beams. This paper presents a methodology to generate realistic range profiles of radar observations at attenuating frequencies, such as X band, for rain medium. Fundamental microphysical properties of precipitation, namely size and shape distribution information are used to generate realistic profiles of X-band starting with S-band observation. Conditioning the simulation from S-band maintains the natural distribution of rainfall microphysical parameters. Data form the Colorado State University CHILL radar and the National Center for Atmospheric Research S-POL radar are used to simulate X-band radar observations. The two procedures and sample applications are presented.