Evaluation of X-band polarimetric radar estimates of drop size distributions from coincident S-band polarimetric estimates and measured raindrop spectra

Recent research has demonstrated the value of polarimetric measurements for the correction of rain-path attenuation at X-band radar frequency and the estimation of rain parameters including drop size distributions (DSD). The issue this study is concerned with is to what degree uncertainties in attenuation correction can affect the estimation of DSD. Since attenuation correction uncertainty enhances with rain path our hypothesis is that DSD retrieval uncertainty at X-band may deteriorate with range. In this study we evaluate the relative accuracy of X-band DSD retrieval against DSD estimates from S- band radar observations and in-situ disdrometer spectra. We present comparisons of various techniques for estimating DSD model parameters from attenuation-corrected X-band dual- polarization radar data. Coincident X-band (XPOL) and S-band (S-Pol) dual-polarized radar measurements from the International H₂O experiment (IHOP) as well as coincident X-band polarimetric radar (MP-X) measurements over disdrometer during a Typhoon storm case in Japan are used to assess the accuracy of the different DSD retrieval algorithms applied to X-band radar.