Recently, Enterprise Electronics Corporation (EEC) in Alabama, collaborated with the U.S. National Severe Storms Laboratory (NSSL) to develop a novel automatic calibration tool (ACAL), which facilitates on-line calibration for S-band and C-band polarimetric weather radars. The ACAL algorithm is based on the physical consistency among polarimetric radar measurements of precipitation, i.e., reflectivity, differential reflectivity, and differential phase. With the continuous execution of ACAL, the radar system generates the automatically-calibrated reflectivity product in real-time.
The current article introduces the theoretical basis of the ACAL algorithm and the ACAL module used in EEC's radar software system—EDGE. The ACAL performance is demonstrated by the case studies with EEC's C-band polarimetric weather radars with various transmitter configurations. The potential uncertainty of calibration is also discussed. Results show that ACAL has a robust calibration performance based on radar measurements of different precipitation events. The variance of calibration term is relatively small as compared to the typical uncertainty of radar measurements.