Radiative properties of ice crystals within cirrus clouds: application to remote sensing

Ice clouds have been identified as one of the most uncertain components in atmospheric research. In recent years, the atmospheric radiative transfer and remote sensing community has made a concerted effort to improve the characterization of cirrus clouds. A number of airborne and balloon-borne observations have demonstrated that cirrus clouds are essentially composed of nonspherical ice crystals with various habits (or shapes) and sizes. In this paper, we report on some recent progresses towards the computation of the single-scattering properties nonspherical ice crystals and the relevant applications to remote sensing and radiative transfer simulations. Specifically, we have developed a database of the optical properties of ice crystals at the infrared wavelengths. In conjunction with the application of the scattering database, we also developed a fast infrared transfer model under cirrus cloudy condition, which is applied to the retrieval of ice clouds from satellite-based infrared measurements.