Attenuation margin requirements in a networked radar system for observation of precipitation

In recent years, it becomes increasingly possible to move the operating frequency of weather radar systems from non-attenuating lower frequencies, such as at S-band, to attenuating higher frequencies, such as at X-band. However, wave is more easily extinct in rain at higher frequencies in which case there will be missing observations. Therefore, rain attenuation is one of the important metrics in radar system design and an extra attenuation margin needs to be applied to the allocation of power budget to meet the required sensitivity. The NSF Engineering Research Center (ERC) for Collaborative and Adaptive Sensing of the Atmosphere (CASA) is advancing a new sensing paradigm using networked short-range radar systems to avoid problematic earth curvature blockage. The CASA ERC has developed a networked radar test bed — Integrated Project 1 (IP1) — in southwestern Oklahoma, using 4 X-band radar of 40 km range to cover an area of 7, 000 km2. In this paper the attenuation margin performance are analyzed in the network context and the metric to design a networked radar system is formed.