| dc.description.abstract | This is the first study of using phased array radar data to investigate the quality
and accuracy of retrieved wind field among different time resolution in Taiwan.
A single-Doppler radar velocity retrieval method, based on an optimally
determined moving frame of reference, is developed. This method enables the recovery
of the complete three-dimensional wind field using reflectivity, and radial wind
observations, detected by a single Doppler radar over multiple volume scans. This
method first computes a set of optimal moving speeds (U, V, W), which can be
functions of the height. The perturbation velocities (u′, v′, w′) are then solved
simultaneously, with respect to the moving speeds, by minimizing a cost function
through the three-dimensional variational (3D-Var) approach. Finally, by adding the
optimal moving speed to the perturbation velocities, a complete three-dimensional wind
field is obtained.
An Observation System Simulation Experiment (OSSE) is conducted to examine
the different time resolution retrieval results from single-Doppler radar observed radial
wind and reflectivity simulated by WRF model. The retrieved results show both of the
different time resolution experiments can retrieval the three-dimensional wind field
accurately and by increasing time resolution can promote the quality of the retrieval
wind field.
In addition, a supercell case during VORTEX2 on 5 June 2009 is investgated in
this study. We use MWR-05XP radar data, which is phased array radar, DOW6 radar
data and DOW7 radar data to test and verify by single-Doppler velocity retrieval
method. The results reveal both different time resolution experiments can retrieve the
vortex structure clearly and by increasing time resolution can promote the quality of
the retrieval wind field and reduce the underestimate of the azimuthal wind field. The
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retrieval results also verify the index (AoR) can be used to determine the quality of the
retrieval wind field. | en_US |