MULTIPARAMETER RADAR MEASUREMENTS IN COLORADO CONVECTIVE STORMS (SCATTERING, PROPAGATION, POLARIZATION, METEOROLOGY, REMOTE-SENSING)

This study represents a comprehensive investigation in which radar observations are integrated with model results to develop reliable inverse scattering methods for the determination of some key microphysical characteristics of precipitation particles in convective storms. Since microphysical properties affecting the microwave radar measurements are composed of many independent details such as size, shape, orientation, and composition, multiparameter radar observations are needed to unfold the complex nature of the problem. The term multiparameter generally refers to dual-polarization or dual-wavelength measurements made in addition to the normally measured radar reflectivity, but excluding Doppler spectrum parameters. The inverse scattering problem is further complicated by the presence of precipitation particles in the medium between the radar and the resolution volume of interest. The propagation medium between the radar and the resolution volume is modeled using the first-order multiple scattering approximation.; A generalized electromagnetic backscatter-cum-propagation model was developed for quantitative investigation of multiparameter radar observables in convective storms. Detailed calculations of multi-parameter observables for rain, graupel, and hail media were performed, and the results were compared with radar measurements. Also, the effect of propagation on the radar backscatter measurements was investigated in the presence of model rain propagation paths. It was shown that S-band Z(,DR) was a robust measurement, while X-band LDR, S-band CDR, and ORTT were seriously affected by moderate-to-intense convective rainfall.; The vertical structure of reflectivity, Z(,DR) and LDR, was computed based on microphysics inferred from a one-dimensional graupel melting model. The results were quantitatively compared with radar measurements, resulting in excellent agreement. Multiparameter radar hail signatures were intercompared for independent verification of presence of hail.; A procedure to retrieve the three parameters (N(,0), m, and (LAMDA)) of a gamma raindrop size distribution (DSD) model from the S-band reflectivity, differential reflectivity, and X-band attenuation is described. It was found that the parameters N(,0) and m were related to each other as suggested by Ulbrich (1983). Sample comparisons between the attenuation computed from gamma DSD and the measured cumulative X-band attenuation demonstrated that the cumulative X-band attenuation could be estimated with fractional standard deviations of around 15-20%.