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Daniel T. Lindsey and Louie Grasso

1. Introduction Cirrus cloud microphysical properties, like optical depth and effective radius, have received much attention in the literature due to their important role in regulating climate (e.g., Liou 1986 ; Stephens et al. 1990 ; Cooper et al. 2006 ). A great majority of satellite retrievals of these parameters has been developed for instruments aboard polar-orbiting satellites, such as the Moderate Resolution Imaging Spectroradiometer (MODIS) and the Advanced Very High Resolution

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Owen B. Toon and James B. Pollack

and optical thickness of stratosphericand tropospheric aerosols is proposed. The uncertainties involved in making the model are emphasized, andsome of the model's implications are discussed. The model is designed for, and biased toward, global averageradiative transfer calculations.1. Introduction Every study of the effects of aerosols on the Earth'sradiation balance requires a d'etailed model of the properties of aerosols. Since the properties of aerosols arenot well known each radiative

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Xiaozhen Xiong, Dan Lubin, Wei Li, and Knut Stamnes

Introduction The effects of clouds still constitute one of the largest uncertainties in the study of climate change, and this is particularly true in the Arctic. Satellite remote sensing has proven useful for deriving some cloud properties, such as cloud fraction, optical depth, effective droplet size, and liquid water path on a global basis (e.g., Twomey and Cocks 1982 , 1989 ; Foot 1988 ; Nakajima and King 1990 ; Nakajima et al. 1991 ; Han et al. 1994 , 1999 ; Platnick and Valero 1995

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Artemio Plana-Fattori, Gérard Brogniez, Patrick Chervet, Martial Haeffelin, Olga Lado-Bordowsky, Yohann Morille, Frédéric Parol, Jacques Pelon, Antoine Roblin, Geneviève Sèze, and Claudia Stubenrauch

emissivity E cld are retrieved by applying a weighted chi-2 method to five radiances along the 15- μ m CO 2 absorption band ( Stubenrauch et al. 1999a ). The relatively high spectral resolution of the TOVS instruments yields reliable cirrus properties, day and night ( Stubenrauch et al. 1999b , 2006 ). The High Resolution Infrared Radiation Sounder (HIRS) component of the TOVS package is sensitive to clouds associated with visible optical thicknesses above 0.1 ( Wylie and Menzel 1999 ). Cloud

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John M. Davis and Stephen K. Cox

optical depth is scaled.1. Introduction The Cloud Field Optical Simulator is a laboratorydevice designed to simulate the radiative properties ofoptically thick clouds in the visible portion of the electromagnetic spectrum. A detailed description of theCFOS apparatus and experimental evidence providingthe initial verification of the process may be found inDavis et al. 0983). Basically, the initial verificationconsisted of a comparison between laboratory simulated and theoretically derived radiances

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James C. Barnard and Charles N. Long

that invoke the plane-parallel, homogenous cloud assumption that is most closely satisfied for fully overcast skies. Therefore, we cannot consider cases of broken cloudiness here. Last, the measured surface irradiances are influenced by the transmission through the cloud, as well as the transmission through the atmospheric layers above and below the cloud. Without detailed information of the vertical distribution of the atmosphere's optical properties, it is not possible to distinguish between the

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Joannes Berque, Dan Lubin, and Richard C. J. Somerville

applied to the Arctic ( Schweiger and Key 1994 ). Advanced Very High Resolution Radiometer (AVHRR) data from the NOAA polar orbiters have been applied with success to the retrieval of Arctic cloud optical properties and the radiation budget. The AVHRR's multispectral capability enables useful retrievals of cloud amount ( Ebert 1987 ), cloud thermodynamic phase ( Key and Intrieri 2000 ), and cloud optical depth and effective particle size ( Han et al. 1999 ; Dong et al. 2001 ; Xiong et al. 2002 ). To

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Bryan A. Baum, Richard A. Frey, Gerald G. Mace, Monica K. Harkey, and Ping Yang

eff ) ranging from 4 to 12 μ m with an effective variance of 0.1. Mie theory is used to provide the optical properties for each distribution, including the scattering phase function, single scatter albedo ( ω ), and extinction cross section. Cirrus microphysical and optical properties are used from four separate models based on in situ cirrus measurements. The four models follow the cold cirrus, cirrostratus, cirrus at T = −40°C, and cirrus uncinus distributions ( Baum et al. 2000a ). The

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Gouri Prabhakar, Eric A. Betterton, W. Conant, and Benjamin M. Herman

:// .] Goering , C. D. , T. S. L’Ecuyer , G. L. Stephens , J. R. Slusser , G. Scott , J. Davis , J. C. Barnard , and S. Madronich , 2005 : Simultaneous retrievals of column ozone and aerosol optical properties from direct and diffuse solar irradiance . J. Geophys. Res. , 110 , D05204, doi: 10.1029/2004JD005330 . Harrison , L. , and J. Michalsky , 1994 : Objective algorithms for the retrieval of optical depths from ground-based measurements

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C. P. Jacovides, Michael D. Steven, and D. N. Asimakopoulos

of gaseous pollutants and aerosol on the solar spectral distribution and to establish whether spectral measurements would be useful for monitoring pollution. The experiment was deployed in the Athens basin (38°N, 24°E) over two weeks, from 16 to 27 May. This study aims to quantify temporal and spatial variations in the spectral distribution of radiant energy in Athens and to identify reasons for such variations. Atmospheric optical properties such as Ångström turbidity parameters and optical

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