32nd Conference on Broadcast Meteorology/31st Conference on Radar Meteorology/Fifth Conference on Coastal Atmospheric and Oceanic Prediction and Processes

Thursday, 7 August 2003
A simple algorithm for eliminating Doppler velocity aliasing
Shuyuan Liu, Peking University, Beijing, China; and H. Wang and Z. Tao
Poster PDF (134.0 kB)

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

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