Issues with Polarimetric Phased Array Radar in Weather Measurements

Weather radar polarimetry has matured to a point that it is being implemented on the national network of WSR-88D Doppler radars. Phased array radar (PAR) technology has been successfully utilized in the military for more than five decades, and has recently been introduced to the weather radar community as the National Weather Radar Testbed (NWRT). Its fast scan capability has revealed detailed evolution of severe storm phenomena such as the microburst, and can significantly advance weather observations. It is envisioned that polarimetric phased array radar (PPAR) has the potential to become the multi-mission radar system for better monitoring our atmospheric environment.

The development and application of PPAR for weather measurements invokes new challenges. For example, cross-polar coupling of the horizontal and vertical polarizations at beam directions away from broadside (i.e., the array face) can cause errors larger than allowed values for weather measurements (0.1 dB for ZDR and 0.01 for ρhv). In this paper, we list issues of weather measurement with PPAR such as system configuration, polarization scheme and calibration, cross-polar coupling, waveform optimization and advanced signal processing. Possible solutions and compromises are discussed.