Study of the Single-scattering and Bulk Radiative Properties of Ice Clouds: Applications to Remote Sensing and Radiative Forcing Assessment

A new numerical model based on the Invariant Imbedding T-matrix (II-TM) principle has been developed to accurately simulate the single-scattering properties, namely, the extinction efficiency, single-scattering albedo, and phase matrix, of ice crystals for small to moderate size parameters. The average of the particle optical properties over random orientations is performed in an exact way within the framework of IITM. A synergetic combination of the IITM and a physical-optics/geometric-optics model provides unprecedented modeling capabilities to solve the scattering of radiation by ice crystals. The downstream applications of the single-scattering properties simulated from the new modeling capabilities, and, consequently, the bulk radiative properties render significant improvements, particularly, in remote sensing implementations and radiative forcing simulations involving ice clouds. For the sensitivity studies related to remote sensing of ice cloud properties, observations made by MODIS (Moderate Resolution Imaging Spectroradiometer), VIIRS (Visible Infrared Imager Radiometer Suite), CALIPSO (Cloud-Aerosol Lidar and Infrared Pathfinder Satellite Observation), and POLDER (POLarization and Directionality of the Earth's Reflectances)/PARASOL (Polarization and Anisotropy of Reflectances for Atmospheric Sciences coupled with Observations from a Lidar) are used. Furthermore, NCAR Community Atmospheric Model (CAM 5) is also used to assess the global ice cloud radiative forcing with the new ice cloud property parameterization.