Enhancements to the National Weather Radar Testbed Phased Array Radar Storm Tracking Function

The National Weather Radar Testbed (NWRT) Phased Array Radar (PAR), located in Norman, Oklahoma, consists of a single antenna array capable of electronically scanning a 90-degree azimuthal sector at any given moment. The antenna, mounted on a pedestal that can be commanded to move to any azimuthal position, allows operators to select the center of the best electronically scanned 90-degree sector to follow areas of interesting weather. At the previous IIPS conference, we presented an adaptive pedestal-control algorithm that automates the process of tracking an operator-defined weather feature. The algorithm provides feedback to the radar control software to adjust the antenna pedestal position in order to continuously keep the weather feature in the field of view. In its original version, the tracking was based on the reflectivity field at the lowest elevation angle. Since then, the algorithm has been enhanced in two ways. First, a 3-D option has been added to utilize the reflectivity field from all available tilts making the tracking more robust. Also, a new capability was implemented to adaptively change the pulse-repetition-time (PRT) to minimize the occurrence of range folding within the storm-tracking region. This paper describes these new capabilities and illustrates the performance improvements that adaptive scanning can provide on the NWRT PAR.