Retrieval of cloud optical properties from infrared hyper-spectral measurements: a new methodology based on a line-by-line multiple scattering code and measured particle size distributions

A new methodology to retrieve cloud optical properties using hyperspectral infrared measurements will be presented. The new method makes use of line-by-line multiple scattering simulations to retrieve spectrally resolved cloud optical depths. The retrieval requires knowledge of the clear sky profile and cloud boundaries. Comparing the spectral optical depths with a pre-computed optical depths database the cloud microphysical properties are retrieved. This database is generated from an ensemble of measured cloud particle size distributions and computed single scattering properties for a variety of ice crystal habits. The full methodology will be applied to several case studies covering different cloudy sky conditions. A comparison with other cloud property retrieval methodologies is also performed. The work will be focused both on aircraft and satellite hyper-spectral measurements (i.e. Scanning High-resolution Interferometer Sounder and Atmospheric Infrared Sounder) with lidar and radar measurements to validate the retrieval results.