Doppler-polarimetric radar research of precipitation

The operation of the Delft atmospheric research radar (DARR), a coherent multipolarization FM-CW radar operating in the S-band, is described. DARR is capable of measuring the Doppler spectrum and the relative scattering matrix of precipitation simultaneously in real time. The polarimetric parameters measured by DARR are the differential reflectivity and the linear depolarization ratio. The Doppler processing results in the first three spectral moments: the main reflectivity, the main velocity, and the variance of the velocity spectrum. It is demonstrated how the differential reflectivity, depolarization ratio, and the Doppler parameters can be used to identify hydrometeor types. It is concluded that the combination of Doppler and polarimetric measurements provides a means to do detailed studies of physical processes in stratiform precipitation. The differential reflectivity can be used to estimate the average shape of the particles, while the linear depolarization ratio supplies information about the asymmetry and orientation of the particles.<
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