dedicated land, towers, and other support infrastructure. The large physical size of these systems, combined with potential environmental impacts and possible interference by and to other radars, limits the availability of potential sites. Scanning of the WSR-88D antenna below 0.5° elevation is prohibited owing to public concerns about radiation safety.
The acquisition cost of each radar unit (including radar equipment as well as land and other installation costs) in current dollars would be approximately $10 million. The annual per-radar operating and maintenance cost has been estimated by Lincoln Laboratory to be $500,000 per radar (JAG/PARP report, Appendix C).
The coverage of the WSR-88D network has been reviewed in several NRC reports (NRC, 1995; 2002; 2005). The protection of lives and property requires weather radar coverage from the height of cloud tops (~ 18 km or 60,000 ft.) down to near-ground level, where damaging storm features such as tornadoes, hail, and downbursts impact both the public and low-flying aircraft. The Weather Service Modernization Act of 1992 established a criterion that the network should provide complete coverage over the CONUS at a height of 3.05 km (10,000 ft.) above ground level (AGL) without degradation in service, compared with the WSR-57 and WSR-74 predecessor networks. Coverage of the WSR-88D network is nearly complete at 10,000 ft AGL over the eastern United States, while gaps exist in the mountainous regions of the Midwest and Pacific Northwest (Serafin and Wilson, 2000).
A 1995 National Research Council study (NRC, 1995) investigated the adequacy of WSR-88D coverage relative to the detection and warning of a variety of weather phenomena (e.g., landfalling hurricanes, supercells, mini-supercells, mesocyclones, tornado vortices, microbursts, macrobursts, and various types of precipitation and snowfall). This study found that WSR-88D coverage over the nation was generally excellent in terms of providing superior forecasting and warning capability compared with the predecessor radar systems. The improved coverage and performance of the WSR-88D network has led to a significant improvement in the short-range forecasts and warnings of severe thunderstorms, tornadoes, and flash floods (Serafin and Wilson, 2000). Nevertheless, the report found a significant lack of low-level coverage that limits the detection of the full range of hazardous weather conditions over large expanses of the CONUS. This issue is discussed further in Chapter 8.