Improving the present understanding of the optical properties of contrails and contrail cirrus and enhancing the global satellite detection and retrieval of these clouds will greatly benefit the evaluation of the radiative impact of aviation-induced cloudiness on climate change.

[1] This paper describes an algorithm for inferring cirrus cloud top and cloud base effective particle sizes and cloud optical thickness from the Moderate Resolution Imaging Spectroradiometer (MODIS) 0.645, 1.64 and 2.13, and 3.75 mm band reflectances/ radiances. This approach uses a successive minimization method based on a look-up library of precomputed reflectances/radiances from an adding-doubling radiative transfer program, subject to corrections for Rayleigh scattering at the 0.645 mm band, above-cloud water vapor absorption, and 3.75 mm thermal emission. The algorithmic accuracy and limitation of the retrieval method were investigated by synthetic retrievals subject to the instrument noise and the perturbation of input parameters. The retrieval algorithm was applied to three MODIS cirrus scenes over the Atmospheric Radiation Measurement Program's southern Great Plain site, north central China, and northeast Asia. The reliability of retrieved cloud optical thicknesses and mean effective particle sizes was evaluated by comparison with MODIS cloud products and qualitatively good correlations were obtained for all three cases, indicating that the performance of the vertical sizing algorithm is comparable with the MODIS retrieval program. Retrieved cloud top and cloud base ice crystal effective sizes were also compared with those derived from the collocated ground-based millimeter wavelength cloud radar for the first case and from the Cloud Profiling Radar onboard CloudSat for the other two cases. Differences between retrieved and radar-derived cloud properties are discussed in light of assumptions made in the collocation process and limitations in radar remote sensing characteristics.

(VIIRS) to retrieve pixel-level mixed-phase cloud optical thicknesses and effective particle sizes using 0.67, 1.6, 2.25, and 3:7 μm bands reflectance/ radiance. This approach utilizes lookup tables of reflectances constructed from radiative transfer simulations and a numerical iterative search method. The capability of this new approach was demonstrated using Moderate Resolution Imaging Spectroradiometer (MODIS) data as proxy to VIIRS. Two proxy scenes, 14 October 2001 over North Platte, Nebraska, during the ninth Cloud Layer Experiment (CLEX-9) and 9 November 2006 over the Great Lakes and Eastern Canada during the Canadian CloudSat/Cloud-Aerosol Lidar and Infrared Pathfinder Satellite Observations Validation Project (C3VP), were analyzed. The performance of the mixed-phase retrieval algorithm was assessed by comparison with the MODIS retrieval products, airborne in situ observations during CLEX-9 and CloudSat data during C3VP.

We undertook a new approach to investigate the aerosol indirect effect of the first kind on ice cloud formation by using available data products from the Moderate-Resolution Imaging Spectrometer (MODIS) and obtained physical understanding about the interaction between aerosols and ice clouds. Our analysis focused on the examination of the variability in the correlation between ice cloud parameters (optical depth, effective particle size, cloud water path, and cloud particle number concentration) and aerosol optical depth and number concentration that were inferred from available satellite cloud and aerosol data products. Correlation results for a number of selected scenes containing dust and ice clouds are presented, and dust aerosol indirect effects on ice clouds are directly demonstrated from satellite observations.

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