Sensitivity Analysis and Retrieval of Ice Cloud Parameters Using Polarized Vector Radiative Transfer Simulations in the Submillimeter/Millimeter and Longwave Infrared Regimes

We conduct radiometric and polarimetric simulations of ice clouds for several wavelengths in the Infrared (IR) atmospheric window region and Sub-millimeter/Millimeter (sub-mm/mm) regimes. Despite there being previous studies utilizing polarized sub-mm/mm bands and IR bands within the atmospheric window region and having been thoroughly investigated for their feasibility to observe ice clouds, especially optically thin cirrus, there are a lack of studies utilizing several of these high frequency bands or polarimetric IR observations to infer ice cloud properties.

We conduct ice cloud simulations for 5 sub-mm/mm frequencies (183 - 680 GHz) and 3 IR wavelengths (8.6 - 12 µm). We then perform retrievals of two ice cloud parameters: ice water path (IWP) and effective diameter (D_eff). While the Moderate Resolution Imaging Spectroradiometer (MODIS) Collection 6 (roughened 8-column aggregates) (MC6) is the primary ice particle model used in this study, we also use the Improved General Habit Mixture (IGHM), a mixture of several ice particle shapes as a function of particle size, as a way to observe how using different ice particle models would affect the results. This study demonstrates that polarized measurements from a majority of the selected sub-mm/mm and IR wavelengths have the potential to effectively retrieve ice cloud parameters. Preliminary results from MC6 simplistic IWP and D_eff isoline retrieval lookup tables displayed retrievals with percent errors as low as 5% but some higher than 50%.