Multi-Layer Effects Ice Cloud Polarimetric and Radiometric Properties in Sub-Millimeter and Thermal Infrared Wavelengths

Retrieval of multi-layered cloud properties, particularly ice water path (IWP), have long presented a difficulty in satellite remote sensing. Previous studies have shown the bias of errors for retrieved cirrus IWP are primarily controlled by the inconsistency in estimated optical depths for single layer ice clouds and ice overlapping water clouds, and that error of IWP increases linearly as the difference in optical depth increases. Our study concerns quantifying the effects of multilayered cloud conditions comprising either multiple ice clouds layers or ice overlapping mixed phase clouds, in determination of cloud IWP. Preliminary results show minimal effects of low level water clouds on retrieval of cirrus IWP. However, the presence of secondary ice clouds, or mixed phase clouds could lead to errors in retrieved IWP values using sub-millimeter and thermal infrared wavelengths. To determine these errors, simulated brightness temperatures (TB) attributed to various multi-layer cloud conditions are compared to those from single ice cloud layers. This study is also concerned with the effects of multi-layered clouds on the polarized difference of cloud brightness temperatures (TBvpol – TBhpol). Polarization difference (PD) is a useful metric in determining ice microphysical properties, such as particle shape and size. By quantifying the effects of multi-layered cloud conditions on simulated TB and PD for sub-millimeter and thermal infrared bands, a more robust retrieval scheme can then be developed for determination of cloud IWP and particle effective diameter over a wider range of atmospheric conditions.