Creating of the scattering and absorption properties database of ice crystals

Abstract

The single-scattering properties of ice crystals are fundamental to the radiative transfer in ice clouds, which thereby are the basis for estimating the optical and microphysical properties of ice clouds. In this paper, with the particle internal reflection, refraction and multiple diffraction correct Van De Hulst anomalous diffraction (ADT), which thereby get more precise calculation for non-spherical ice crystal particle scattering and absorption properties. Six ice crystal habits, including aggregate, bullet rosette, column, hollow column, plate, droxtal. The database of the single-scattering properties for each of these ice particles has been developed at 56 wavelengths between 0.2 and 5µm and for particle sizes ranging from 3 to 4000µm specified in terms of the particle maximum dimension. MODIS is the first satellite-borne instrument that features the 1.375µm channel for cirrus cloud study. The paper analyzes that the scattering properties of ice particles can change the trend with the effective scale, when the fixed wavelength is 0.55µm and 1.375µm. Further, various analytical expressions as functions of the effective dimensions of ice crystals have been developed to parameterize the extinction, absorption efficiencies and asymmetry factor. This method for the establishment of non-spherical ice crystals particle absorption and scattering properties of the database is useful. The database on optical properties of ice clouds, is the foundation of retrieving and data processing based on satellite remote sensing.