Demonstration of a Spaced-Antenna Weather Radar Using an X-Band Active Phased-Array

Spaced-antenna (SA) retrievals are a potential means of higher spatial-resolution wind-field retrievals than currently available single weather radar techniques. Relevant literature to date has focused on theoretical, numerical or engineering aspects. In a stratiform precipitation event case study with a median spectrum width of 0.53 m/s, we evaluate SA retrievals. The X-band active phased-array spaced antenna retrievals exhibited better measurement fidelity relative to simulated performance of the S-band national weather radar testbed (NWRT). This allowed for the first interpretation and evaluation of SA retrievals on precipitation echoes. SA measurements were confirmed to be in quadrature with radial velocity estimates. This signature is qualitatively consistent with simulation predictions for a spatially invariant wind field, where the radial velocity maximum corresponds to a null in the SA retrieval. Finally, SA retrievals were in agreement with reference wind field proxies derived using Doppler beam swinging (DBS) and velocity azimuth display (VAD) techniques. Among the SA techniques implemented, the time-domain Gaussian slope at zero lag (G-SZL) algorithm was found to perform better than the frequency domain full spectral analysis (FSA) algorithm. This is because the parametric nature of the G-SZL algorithm resulted in better immunity to correlation coefficient estimation errors.