This study examines the development of bulk single-scattering properties of ice clouds, including single scattering albedo, asymmetry factor, and phase function, for a set of 1117 particle size distributions obtained from analysis of FIRE-I, FIRE-II, ARM-IOP, TRMM-KWAJEX, and CRYSTAL-FACE data. The primary focus is to develop band-averaged models appropriate for use by the MODIS imager on the EOS Terra and Aqua platforms, specifically for bands located at wavelengths of 0.65, 1.6, 2.1, and 3.75µm. Our results indicate that there are substantial differences in the bulk scattering properties of ice clouds formed in areas of deep convection and those that exist in areas of much lower updraft velocities.

Band-averaged bulk scattering property results obtained from a particle-size dependent mixture of ice crystal habits are compared to those obtained assuming only solid hexagonal columns. The single scattering albedo is lower for hexagonal columns than for a habit mixture for the 1.6, 2.1, and 3.75µm bands, with the differences increasing with wavelength. In contrast, the asymmetry factors obtained from the habit mixture and only the solid hexagonal column are most different at 0.65µm, with the differences decreasing as wavelength increases. At 3.75µm, the asymmetry factor results from the two habit assumptions are almost indistinguishable. The asymmetry factor, single-scatter albedo, and scattering phase functions are also compared to the MODIS V1 models. Differences between the current and V1 models can be traced to the microphysical models, specifically the number of both the smallest and the largest particles assumed in the size distributions.