Identification of cloud ice crystals using a 95 GHz polarimetric radar

Abstract

The identification of various ice crystal types within a cloud, as well as the estimation of their ice water content are important goals with applications to cloud microphysical studies and to understanding the effect of clouds on the Earth's radiation budget. Millimetre wave polarimetric radars have the potential for accomplishing both of these goals. There are several millimetre wave radars operating at 95 GHz for the remote sensing of ice clouds from ground-based and airborne platforms. This paper brings together observations from experiments and modeling studies, and focuses on 95 GHz polarimetric radar signatures of ice crystals including pristine crystals such as columns, plates, and stellar crystals, as well as dendrites, ice crystal aggregates, and graupel. Results from simulations and from experimental data for several polarimetric radar observables are combined to generate different ranges of values for each observable corresponding to different crystal types. A simple fuzzy logic classification scheme is presented for identifying crystal types based on these ranges. Suggestions for further development and refinement of this scheme are given.