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J. G. DeVore

) of the aureole spectral radiance profile L A ( θ ) (W cm −2 sr −1 μ m −1 ) or of the effective phase function P ( θ ) for the ensemble of scatterers, since L A ( θ ) and P ( θ ) are linearly related when single scattering applies. The retrieved size a was related to the scattering angle θ by simple diffraction theory: a = λ /2 θ . Absolute scaling of n ( a ) was then determined using the vertical cloud optical thickness (COT or τ ) of the layer found from measurement of the

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Yousuke Sato, Kentaroh Suzuki, Takamichi Iguchi, In-Jin Choi, Hiroyuki Kadowaki, and Teruyuki Nakajima

) due to the lower inversion height. Fig . 5. Normalized PDF of (a) optical thickness and (b) effective radius obtained from satellite observation by NN95 (solid line) and from the control (Na1/H0) simulation (dotted line). c. Aerosol regeneration processes The smaller COT and the larger RE simulated by the model may be attributed to insufficient aerosol amount in the model, where aerosols are only consumed by the nucleation process without any supply. To explore this effect on the cloud formation

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Jean-Louis Brenguier, Hanna Pawlowska, Lothar Schüller, Rene Preusker, Jürgen Fischer, and Yves Fouquart

appropriate to develop parameterizations based on droplet concentration, a parameter which can be directly linked to the aerosol properties. Locally LWC and the droplet sizes are related to the droplet number concentration N via w = (4/3) πρ w Nr 3 υ , (1) where w is the liquid water content, ρ w is the liquid water density, and r υ is the mean volume radius of the droplet spectrum. Various formulas have been proposed in the literature for deriving the optical thickness τ from LWP and the

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Yolanda L. Shea, Bruce A. Wielicki, Sunny Sun-Mack, and Patrick Minnis

aerosol indirect effect can be better constrained by reducing uncertainty in cloud amount, cloud optical thickness, and water cloud effective radius trends. Here, we will focus on the connection between the aerosol indirect effect and water cloud effective radius. A decrease in water cloud effective radius may be indicative of an increased number of cloud condensation nuclei, which are typically dominated by aerosol particles ( Twomey 1977 ). To better constrain radiative forcing and cloud feedback

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J. V. Dave

significantly from thecorresponding input to the models with the difference between these two values depending on several factorssuch as solar zenith angle, aerosol parameters and the wavelength pair used in the estimation. For an aerosolattenuation optical thickness of about 0.2 at 0.3800 ~sm (average haziness under clear sky conditions), thisdifference is about 0.006 atm-cm provided the analysis is restricted to cases with solar zenith angles <85°.For strong hazy conditions represented by the

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Qingyuan Han, William B. Rossow, and Andrew A. Lacis

Northern Hemisphere than in theSouthern Hemisphere. The height dependencies of cloud droplet radii in continental and marine clouds arealso consistent with differences in the vertical profiles of aerosol concentration. Significant seasonal and diurnalvariations of effective droplet radii are also observed, particularly at lower latitudes. Variations of the relationshipbetween cloud optical thickness and droplet radii may indicate variations in cloud microphysical regimes.1. Introduction Cloud

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R. Michael Reynolds, Mark A. Miller, and Mary J. Bartholomew

1. Introduction Aerosols over the oceans are especially difficult to characterize because there are gaps in the fundamental knowledge about their climatology due in part to the absence of detailed, widespread observations ( Haywood et al. 1999 ). Aerosols have a cooling effect on global climate, which can stabilize or perhaps even overcompensate the warming effect of greenhouse gases and thus lead to long-term cooling of the global climate ( Schwartz 1996 ). Aerosol optical thickness (AOT

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François-Marie Bréon and Sophie Bouffiés

typicalstratospheric aerosol layer of optical thickness 0.05 and altitude 20 kin. A boundary layer aerosol has a smallerinfluence. In clear conditions, the uncertainty on the apparent pressure is on the order of 100 hPa. Therefore, a clouddetection test based on the oxygen absorption will only be able to detect medium and high clouds.1. Introduction The surface pressure is an important meteorologicalparameter that is not currently measured from satellites. In the past decades, several authors have

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R. A. Sutherland, R. D. McPeters, G. B. Findley, and A. E. S. Green

sun. These results are also used in conjunction with absolute irradiance measurements at the ground levelmade with a single monochromator equipped with solar blind photomultiplier and a long-wavelength NiSO4rejection filter. The comparison of the observations with calculations based upon the detailed extraterrestrialspectrum of Arvesen is used to determine the ozone thickness and the aerosol optical depth. We discuss thelimitations of our results and work which remains to be accomplished.1

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Mao-Sung Yao and Anthony D. Del Genio

convective and large-scale clouds in climate models appear to produce a threefold variation in one measure of global climate sensitivity ( Cess et al. 1990 ). Notable cloud feedbacks involve changes in cloud height, cloud cover, and cloud optical thickness. Cloud height appears to have a positive feedback for models with prescribed optical thickness decreasing with height. High clouds tend to increase while low and middle clouds tend to decrease by a larger amount in the majority of doubled CO 2

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