An Investigation of the Moving-Frame Single-Doppler Wind Retrieval Technique Using Taiwan Area Mesoscale Experiment Low-Level Data

Abstract

The moving-frame single-Doppler radar wind retrieval technique is investigated using field experimental data observed during the 1987 Taiwan Area Mesoscale Experiment intensive observation period 2. Emphasis is placed on studying the impact of the geometric position of the radar in relation to the quality of the retrievals. Experiments show that this technique is capable of recovering the missing cross-beam wind components, but their magnitude is always underestimated. As a consequence, when the unobserved tangential components are smaller than the observable radial components, the best results are produced. By contrast, if the unknown cross-beam winds considerably exceed the radial winds because of a disadvantageous relationship to the radar observation site, the retrievals become less reliable. However, even without a priori knowledge of the true flow structure, which is always the case in reality, this single-Doppler retrieval scheme demonstrates its ability to distinguish which component (radial or azimuthal) is greater. In other words, when the tangential component completely dominates the radial winds, this message can be correctly delivered through the retrieval algorithm to alert the users so that the radar data and these single-Doppler-retrieved results will be interpreted and used with caution.