Radar spectral polarimetric processing to improve doppler spectra of rain and clouds for enhanced profiling and micropysical retrievals

Spectral polarimetry is based on combined simultaneous Doppler and polarization measurements, with a close look on the polarization dependence of the radar signal per velocity bin of the Doppler spectrum. The principle of radar spectral polarimetry and the main steps of the related processing are given in the paper. The processing results in clutter- and noise-free atmospheric spectrographs (Doppler spectra for every height). When the processed spectrographs are integrated to calculate the classical Doppler moments, the resulting estimates of reflectivity, mean Doppler velocity, Doppler width and polarimetric parameters are improved. Improved profiles have the potentiality to lead to better estimates of rain rates, liquid water and ice water content, and wind. In the paper, illustration is provided in the context of wind profiling, which employs as input mean Doppler velocity profiles. Another application consists of linking the processed Doppler spectrum with the Particle Size Distribution (PSD) of the medium being probed. Thus, in addition to the more traditional method of expressing the Doppler spectrum in its statistical moments, spectral polarimetry can also provide detailed microphysical information of precipitation and clouds in the case of slant profiling. One illustration is shown in the case of mixed-phase clouds. Both illustrations are part of the extended data set collected by the S-band radar TARA (Transportable Atmospheric RAdar) within the COPS campaign (Convective Orographycally-induced Precipitation Study) in the black forest in Germany during the summer of 2007.