Application of adaptive beamforming to mitigate contamination on wind profiler A novel technique was developed for profiling radars to measure atmospheric wind fields when signals are contaminated by migrating birds. It exploited the idea of adaptive beamforming to suppress the interference from birds to provide accurate three-dimensional wind measurements using a spaced antenna system. Numerical simulations were implemented to investigate the performance and the limitation of the proposed technique. The feasibility of atmospheric wind measurements was further demonstrated by using the experimental data. Wind measurements from the full correlation analysis (FCA) and postset beam steering (PBS) were also provided for comparisons. During the period when a single bird was present in the radar beam, the proposed technique produces wind estimates that were consistent with atmospheric wind field prior to the entry of the bird, while both FCA and PBS wind estimates were biased. Reference: Chen et al., 2007.

Beam broadening effect on Doppler spectral width of wind profiler The beam broadening effect on Doppler spectrum was investigated with theoretical derivation and numerical simulation. It was found that vertical wind may cause a beam broadening spectrum not in exact Gaussian shape. Moreover, the azimuth angle variation of the beam broadening spectral width in the presence of vertical wind was more significant than that in the absence of the vertical wind. The widths of the beam broadening spectra for oblique beams pointing in the opposite directions were different. Further, wind shear effect on the azimuth anisotropy of the beam broadening spectral width was also studied. In the context of three‐dimensional wind field with vertical shear of horizontal wind, an analytic expression of the beam broadening spectral width was proposed. A comparison between the analytic expression and simulation results suggested that the expression is applicable in general. Reference: Chen and Chu, 2011.