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C. J. Grund and E. W. Eloranta

altocumulus and icecloud scattering properties, and conclude with thecharacterization of the optically thicker cirrus layer.Throughout this discussion we will refer to the opticalproperties defined in the Appendix. In addition, thereported optical thicknesses (r) have had the effects ofmolecular extinction removed so that they representonly the attenuation due to particle scattering. Likewise, backscatter cross sections represent aerosol scattering quantities without molecular scattering contributions

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Angela Benedetti and Frédéric Vitart

mode of variability in AOD was indeed correlated to the time scales of the MJO. The MJO-related intraseasonal variance accounts for about 25% of the total aerosol optical thickness variance over the tropical Atlantic ( Tian et al. 2011 ), primarily through its influence on the Atlantic low-level zonal winds. Figure 8 shows the average distribution of aerosols in terms of optical depth from the PROG1 experiment over the period 2003–15 averaged over the first month of integration (May). The top

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Hélène Chepfer, Gérard Brogniez, Laurent Sauvage, Pierre H. Flamant, Vincent Trouillet, and Jacques Pelon

by Deuzé et al. (1988a) . This method is based on the assumption of single scattering, which allows us to write the aerosol total reflectance ρ ( λ, Θ), for the wavelength λ, as follows: where Θ is the scattering angle and P a (Θ) the aerosol single scattering phase function. Aerosol optical thickness δ ( λ ) is assumed to follow the Angström law: δ ( λ ) = δ o λ − α , (10) where α is the Angström coefficient and the constant δ o is the

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Saad Mohalfi, H. S. Bedi, T. N. Krishnamurti, and Steven D. Cocke

-scattering albedo ( ω̃ ), the asymmetry parameter ( g ), and the optical thickness ( τ ) were incorporated into the dust aerosol radiation packages of the FSU Limited Area Model. Following Joseph et al. (1976) and Carlson and Benjamin (1980) , these parameters were modified before their use in the Delta-Eddingtion radiative transfer calculations as follows: where τ *, ω * , and g * are the actual values and τ, ω, and g are the scaled values of optical thickness, single

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Frédérique Chéruy and Filipe Aires

retrieved liquid or ice cloud optical thickness τ Liq and τ Ice . To avoid unrepresentative very low optical thickness likely representing aerosols more than clouds, all pixels with an optical thickness less than 0.3 have been eliminated. In this particular region, this leads to a 10% discard of the cloudy pixels. The bispectral (infrared and visible) retrieval of cloud properties suffers from large ambiguities when dealing with optically thin clouds. The sensitivity of the results to the optically

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Toby N. Carlson

visiblespectrum is associated with increased dust concentrations in the atmosphere. Quantitative evidence for a near linear relationship between dustamounts or aerosol optical thickness and refiectivity (specifically the reflected radiance) has beenshown to exist for Saharan dust (Griggs, 1975;Fraser, 1975; Carlson and Wendling, 1977, hereafter CIt0. Until recently, the concept of transforming br/ghthess patterns measured by satellite to isopleths ofaerosol optical depth or to isopleths of mass

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Laurent Sauvage, Pierre H. Flamant, Hélène Chepfer, Gérard Brogniez, Vincent Trouillet, Jacques Pelon, and Franck Albers

transfer code ( Morcrette and Fouquart 1985 ) and a maritime aerosol model ( WCP 1986 ). An aerosol optical thickness at 550 nm of 0.138 between 0 and 5.2 km of altitude (and 0.013 between 0 and 1.5 km) is used to fit the measurements with theoretical values. A value of the plane albedo ( a ) of the sea–cirrus cloud–atmosphere system is derived from the pyrgeometer data recorded by the Falcon (F) overflying the cirrus layer: Figure 6 shows the plane albedo as a function of

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M. Kästner, K. T. Kriebel, R. Meerkötter, W. Renger, G. H. Ruppersberg, and P. Wendling

. KrieBel, DLR, lnstitutflit Physik der Atmosph~ire, D-8031 Oberpfatfenhofen, Federal Republic of Germany.however, this depends strongly on their height, thickness, and microphysical composition (Stephens et al.'1990). Still in question is which optical properties (e.g.,albedo and infrared emittance) shall be assigned to highclouds within the present climate as well as in a warmerclimate, depending on meteorological field quantitieslike temperature, humidity, and wind. Improved fieldmeasurements and

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Jason A. Otkin and Thomas J. Greenwald

-top pressure (CTP), cloud optical thickness (COT), and cloud water path (CWP), are routinely available on a near-global basis from a variety of sensors. Although the accuracy of many satellite-derived datasets is generally too low to provide an absolute measure of the observed cloud properties (e.g., Zhang et al. 2005 ), such datasets are valuable for evaluating the realism of simulated cloud fields. Prior studies have used satellite data to identify sensitivities in a model’s microphysics scheme ( Zhang

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H. Chepfer, M. Chiriaco, R. Vautard, and J. Spinhirne

confirmation, the GLAS operational data products ( Spinhirne et al. 2005 ) are shown in Figs. 1d–f . The operational-derived cloud-height levels indicate the presence of clouds as shown previously but also some aerosol layers are found episodically in the boundary layer. Aerosol particles are not taken into account in the lidar simulated profiles. Also shown in Fig. 1 are calculations of cloud optical thickness of layers and the lidar multiple scattering factor, described later, as effective for the

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