Analysis of X-Band Dual Polarization Radar Observations over Multiple Complex Terrain Regions

Difficulties in representation of high rainfall variability over mountainous areas using ground based sensors is an open problem in hydrometeorological applications. The use of short-range dual polarization X-band radar gives the advantage of multiparameter measurements near ground that carry significant information, useful for estimating drop size distribution (DSD) and rainfall rate. To retrieve precipitation and microphysical estimates from X-band dual-polarization radar, an in-house set of algorithms applied (SCOP-ME). The SCOP-ME algorithm uses optimal parameterization and best-fitted functions of specific attenuation coefficients and backscattering differential phase shift. High-quality and high-resolution precipitation fields derived over the study regions Northeast Italian Alps, North Carolina, Olympic Mountain, Southern tip of Vancouver Island, Rocky Mountains Colorado, Swiss Alps and Arizona. Even though these measurements are at fine spatio-temporal scale and are less inhibited by complex terrain, their estimates have uncertainties that necessitate error characterization and correction procedures based upon in situ measurements. In situ observations from each site used to evaluate the error characteristics of SCOP-ME retrieval to evaluate the self-consistency and accuracy of the attenuation-correction and rain microphysics estimation algorithm. The SCOP-ME algorithm is evaluated based on both radar parameters calculated from the disdrometer data and rainfall rates measured by rain gauges. In addition, the SCOP-ME retrievals of median volume diameter (D₀) and normalized intercept parameter (N_W) are evaluated against the calculated parameters by the in-situ disdrometer spectra observations. Finally, the rain-path attenuation horizontal and differential attenuation reflectivity ray-paths are evaluated based on disdrometers located at different radar-ranges. The aim of this study is to quantify the error of SCOP-ME retrieval applied on the X-band radar measurements, so that these data are properly applied in validation studies of PMW precipitation estimates over complex terrain.