An ability to detect mixed phase conditions and to retrieve their optical properties is important for numerical weather prediction and civil and military aircraft operations. In the current National Polar-orbiting Operational Environmental Satellite System (NPOESS) Visible Infrared Imaging Radiometer Suite (VIIRS) cloud algorithm chain, cloud phase is determined by the NPOESS/VIIRS cloud mask, which has been designed specifically to differentiate between a mixed phase cloud and a condition of thin ice cloud overlapping water cloud. Subsequently, separate optical property retrieval algorithms are applied to these dual-phase pixels, which are treated either as water cloud or as ice cloud.

This poster describes a new approach developed for the NPOESS to retrieve pixel-level, mixed-phase cloud optical thickness (COT) and effective particle size (EPS) from radiances observed in the 0.67, 1.6, 2.13 and 3.7μm bands. The COT and EPS are retrieved from a numerical search method using look-up tables of reflectances for the four bands based on radiative transfer simulations. The capability of this new approach has been demonstrated using MODIS data as a proxy to VIIRS. A proxy scene, October 14, 2001 over North Platte, Nebraska during the ninth Cloud Layer Experiment (CLEX-9) has been analyzed. For this date, airborne in situ observations by the University of Wyoming King Air Cloud Research Aircraft were collected, collocated and coincident with Terra/MODIS overpass. Layers of mixed-phase clouds were detected through these in-situ measurements. Results of comparison between retrieved and observed cloud optical properties will be presented in the conference, along with discussions on the potential application of this new approach.