Retrieval of storm microphysics using K/sub a/ band radar observations

摘要

Polarimetric radar measurements can be used to deduce the shape and orientation of non-spherical scatterers in the Rayleigh scattering regime. At K/sub a/-band and for larger sized particles, Mie scattering effects dominate by introducing oscillations in differential backscattering parameters. Albeit at these frequencies deducing the mean shape of non-spherical scatterers might be difficult, radar backscattering signatures like the linear depolarization ratio (LDR), differential propagation phase (KDP) and co-polar cross-correlation coefficient provide information about the thermodynamic phase state of the scatterers. Tumbling non-spherical particles such as graupel and hail, exhibit enhanced depolarization characteristics which can be used to delineate regions of ice, melting-ice and rain. Additionally, forward scattering parameters such as attenuation and differential attenuation between H and V polarized waves display monotonic increase with the size of the scatterer. Polarimetric radar modeling of hydrometeors such as graupel, hail and rain at 35 GHz (K/sub a/-band) based on the Mueller matrix formulation is presented. The various transitory thermodynamic phase states of ice hydrometeors have also been incorporated in the modeling. In the Rayleigh regime scattering parameters such as differential reflectivity and LDR are used to investigate the feasibility of deducing the mean axis-ratio and spread in the canting angle distributions of these types of hydrometeors. The modeling results could be applied to understand and interpret LDR signatures recorded by airborne radars with vertical incidence.