Determination of ice cloud models using MISR and MODIS measurements

Representation of ice clouds in radiative transfer simulations is subject of uncertainties associated with the shapes and sizes of ice crystals within ice clouds. The error caused by ice cloud models and their scattering properties can be addressed through analyses of viewing angle dependence of retrieved spherical albedo of ice clouds. In our study, ice cloud models are developed based on a combination of multiangle measurements from the Multi-angle Imaging SpectroRadiometer (MISR) instrument and measurements of cloud reflectances provided by the Moderate Resolution Imaging Spectroradiometer (MODIS). Ice crystal habits, including surface smooth and rough and inhomogeneous hexagonal ice crystals are considered in light scattering computations. The difference between cloud spherical albedo and its averaged value over nine viewing angles can be used to test the validity of ice cloud models associated with morphological parameters of ice crystals and particle size and habit distributions. The derived ice cloud model can be incorporated into the retrievals of ice cloud optical thickness and effective particles size using MODIS measurements. The employment of the MODIS instrument on Terra provides additional information on the retrieval of ice cloud effective particle size. Our preliminary results suggest that a mixture of rough and inhomogeneous ice cloud models shows minimally better performance than all of the considered models.