Meteorological Phased Array Radar Research at NOAA’s National Severe Storms Laboratory

The U.S. National Oceanic and Atmospheric Administration (NOAA) has begun evaluating strategies for replacement of the current Weather Service Radar 88 Doppler (WSR-88D) by 2040, when this system is projected to reach the end of its operational lifetime. In addition to maintaining the WSR-88D’s capabilities to detect and classify meteorological scatterers with high sensitivity and spatial resolution, NOAA has articulated goals for more rapid temporal scanning and expanded low altitude coverage. Research at NOAA’s National Severe Storms Laboratory over the past 15 years has demonstrated that phased array radar (PAR) could support volume scan rates of up to once per minute, and that this would improve the ability of forecasters to warn of severe weather. The rapid scan data would also enhance the effectiveness of radar data-assimilation into “Warn on Forecast” systems. This paper discusses three key issues for meteorological PAR: (1) a plausible architecture for a phased array system meeting NOAA’s objective requirements; (2) the feasibility of calibrating co- and cross-polar radiated fields with sufficient accuracy to robustly correct polarimetric weather variable estimate biases when the beam is electronically steered off-broadside; and (3) the capability to scan significantly faster than the WSR-88D through use of multiple, simultaneously active receive beams and other adaptive techniques. Our positive outlook in each of these areas indicates that PAR’s operational benefits to NOAA should in the future be achievable.