Principles of networked weather radar operation at attenuating frequencies

Conventional meteorological radars provide coverage for long ranges (often hundreds of kilometers) and support weather surveillance and hydrological monitoring applications by using high power transmitters and mechanically scanned antennas. These systems operate at wavelengths in 5–10 cm range in order to minimize attenuation due to precipitation, and this necessitates the use of physically large antennas to achieve good resolution at distant ranges. Research radars with observations at short ranges have demonstrated great potential for “targeted applications” such as tornado detection and flash flood monitoring. Therefore it would be desirable to develop radar systems for targeted applications. The usefulness of radar to a specific application is heavily dependent on the accuracy and resolution of coverage. A fundamental physical limit imposed by transmission from single radar is the problem of changing resolution as a function of range. In addition the lowest coverage altitude gets higher with range due to earth curvature. As an alternate solution, a networked radar environment concept has been proposed (Chandrasekar and Jayasumana, 2001; McLaughlin, 2001). The basic principle of the networked radar environment is to be able to provide good coverage, in terms of accuracy and resolution to a large area through a network of radars. In order to be able to provide “economically feasible” solution to this approach, meteorological radar operation must change from the “preferred” S band operation to higher frequencies (just as space borne weather radar systems). However there are new sets of problems at higher frequencies, the major one being the impact of attenuation due to precipitation. In addition the requirement for combining observation from multiple radars also provides additional sets of challenges. The U.S National Science Foundation recently established an Engineering Research Center titled the Center for Collaborative Adaptive Sensing of the Atmosphere (CASA),