Nighttime Retrievals of Ice Cloud Properties from Infrared Radiances at 3.7, 6.7, 11.0 and 12.0 μm

A method to retrieve ice cloud optical thickness, effective particle size, and cloud-top temperature during the nighttime is developed using the infrared brightness temperatures at 3.7, 6.7, 11.0, and 12 μm. This method is primarily developed from a detailed sensitivity study of the infrared radiances over a deep convective cloud system during TC4 experiment on 5 August 2007 by combining measurements from the MODIS Airborne Simulator, Cloud Physics Lidar, Cloud Radar System, and several instruments for particle size measurements. Ice clouds are firstly identified as four types: cirrus, cirrostratus, anvil cirrus, and deep convective clouds in the developed method on the basis of the developed thresholds. For each type of ice cloud, different combinations of the four bands of 3.7, 6.7, 11.0, and 12 μm are used to estimate cloud optical thickness, effective particle size, and cloud-top temperature. The method is applied to a collocated flight track of a MODIS granule with CALIPSO and CloudSat and the retrieved results are compared to CALIPSO/CloudSat measurements.