Polarimetric scattering characteristics of one planar (4 branches) and three spatial (4, 6, and 8 branches) bullet rosette models for sizes from 0.03 to 2 mm were evaluated. The electromagnetic scattering calculations were performed at 35, 94, and 220 GHz frequencies using the T-matrix method for small sizes and the finite-difference time-domain method (FDTD) for large sizes. Three previously analyzed crystal models (column, plate, and stellar crystal) were also included in the evaluations.; At 220 GHz, spatial rosettes could be distinguished from spheres using either the linear depolarization ratio (LDR), or the copolarized cross-correlation coefficient At 35 and for 94 GHz up to 1 mm, the spatial rosettes did not display measurable polarimetric signatures. Using LDR (or ), columns could be distinguished from oriented spatial and planar crystals at vertical incidence, and from randomly oriented spatial rosettes by scanning the radar elevation angle. An equal volume study comparing columns with capped columns, and plates with double plates, found differences in the magnitudes of the polarization parameters, but not in the trends.; Simulations of radar parameters were developed using gamma model size distributions. Relationships were established between the backscattering cross sections and the particle maximum dimension, the effective reflectivity factor (Zh) and difference reflectivity (ZDP), and ice water content (IWC) and Zh. A technique was developed to estimate the fraction of Zh due to aggregates in a mixture with columnar or planar ice crystals using the measured (Zh) and ZDP.; Six cases of aircraft penetrations into cold clouds were evaluated from a 1997 University of Wyoming field campaign in Laramie, Wyoming. An onboard 95 GHz polarimetric radar made measurements at side and vertical incidence, while onboard optical array probe measurements were used to infer particle type. Comparisons of the side incidence radar data with the simulated Z h-ZDP relations suggested that planar and columnar crystal types may be identified and the presence of aggregates may be inferred based on Zh and ZDP measurements.
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