Doppler weather radar is widely used to measure mesoscale weather systems. However, Doppler velocity aliasing occurs when the radial component of the target°¯s velocity is greater than the Nyquist velocity of the radar. A new dealiasing algorithm for Doppler velocity is put forward in this paper. This algorithm is based on the characteristics that the wind field is continuous along a ring centered at the radar and the unfolded Doppler velocity-azimuth curve is close to a first-order harmonic curve and always has a maximal away-speed and a maximal toward-speed with approximately equal value. Unlike most existing Doppler velocity dealiasing algorithms, it does not require manual (or computer) judgement about aliased velocities as a priore or the knowledge of auxiliary wind measurement. The test results of two cases of typhoon show that the new algorithm is not only effective for the single-aliasing case, but also for multi-aliasing case.

Based on the relationship between the amplitude (A) of a first-order harmonic curve of the velocity-azimuth profile and the average of the absolute value of velocity of all points on the profile (|Va| ) is A=1.57*|Va| . The results of quantitative estimation using this relationship show that the VAD curves of each ring are close to a first-order harmonic curve after being dealiased by the new algorithms, so the dealiasing procedure should be successful.

Keywords£ēDoppler weather radar, velocity aliasing, harmonic curve