Towards an Improved Retrieval of Ice Cloud Properties

The report presents the results of a Visiting Scientist Activity within the SAF on Climate Monitoring (CM-SAF) of EUMETSAT. This study assesses the improvemens that can be made to algorithms for the retrieval of cloud optical thickness and ice water path for ice clouds from visible and near-infrared satellite radiances. An analyis is made of the uncertainties in cirrus cloud radiative transfer modeling due to differences in crystal shapes and sizes, vertical cloud structure and, crystal orientations. The present study focuses on particle shapes, sizes and vertical cloud structure, the latter being available from the CloudNET experiment.

The results demonstrate that reflected radiances of ice clouds distinctly depends on the vertical profile of particle size. Furthermore, more realistic profiles with smaller particles near the cloud top lead to a significant brightening of the cloud which moves the modeled spectral reflected radiance closer to the observations.