An Overview of Weather Calibration for the Advanced Technology Demonstrator

The Advanced Technology Demonstrator (ATD) is an S-band planar polarimetric phased array radar (PPAR) at the National Severe Storms Laboratory (NSSL) in Norman, OK. It serves as a testbed for evaluating the suitability of PPAR technology for weather observations. The major challenge to PPAR weather observations is the calibration needed to produce polarimetric measurements comparable to radars using parabolic reflectors. This is due to the existence of significant cross-polar patterns, as well as the scan-dependent measurement biases inherent to PPAR. To address the former, a pulse-to-pulse phase coding technique has been proposed. However, it does not affect the scan-dependent system biases. The effects of these variations must be addressed via corrections using appropriate values at each boresight location. In this work, an overview of weather calibration for the Advanced Technology Demonstrator is presented.