High-resolution Rainfall Rate and Dsd Estimation from X-band Polarimetric Radar Measurements

This study proposes investigation of new attenuation correction and microphysical retrieval methods for X-band polarimetric radar (XPOL). It will concentrate on exploring the dependence of the retrieval on raindrop size distribution variability, and its sensitivity with respect to the selection of oblateness-size relation (or axial ratio) and maximum diameter limit. Variations in the assumed form of the raindrop axial ratio may result in significant biases in attenuation and microphysical retrievals. In addition, at this wavelength, resonance occurs for sizes larger than about 4 mm, and therefore several polarimetric variables exhibit non-monotone dependence on the drop diameter. An algorithm is developed and experimentally validated for retrieving DSD model parameters. The DSD model is assumed to be a three-parameter “normalized” gamma distribution. Coincidental and closely matched radar rays from non-attenuated (S-band) dual-polarization radar measurements and corresponding DSD retrievals are used to validate the proposed XPOL algorithm in terms of attenuation correction, as well as DSD parameter retrievals.