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Pavel I. Ionov and Andrew K. Mollner

) methods, with sun photometry ( Holben et al. 1998 ) being the most relied on method for calibrating space-based passive sensors ( Kahn et al. 2007 ; Kokhanovsky and de Leeuw 2009 ). Aerosol optical thickness [AOT; or aerosol optical depth (AOD)] is the value of primary interest measured by the passive instruments: It is a column integral (over altitude z ) of aerosol extinction α a that makes no distinction between the contributions from aerosol scattering and aerosol absorption. Active remote

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

contamination of the atmospheric signal. This paper addresses uncertainty in marine FRSR measurements of aerosol optical thickness, τ λA . Subjects ranging from the impact of platform motion on measurement uncertainty through uncertainties in calibration are discussed. A lofty goal, on land as well as at sea, is to measure τ λA with an uncertainty of approximately 0.02 for solar zenith angles from 0° to 70° (3 ≥ m ≥ 1, where m is the atmospheric air mass; m ≅ sec θ e ). The basic issues that

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Gennady K. Korotaev, Sergey M. Sakerin, Aleksandr M. Ignatov, Larry L. Stowe, and E. Paul McClain

Institute, Sevastopol, Crimea, USSR LARRY L. STOWE AND E. PAUL MCCLAINNOAA /NESDIS, Satellite Research Laboratory, Washington, D.C.(Manuscript received 8 April 1992, in final form 4 January 1993) ABSTRACT This paper deals with the problem of aerosol optical thickness (~) retrieval using sun-photometer measurements. The results of the theoretical analysis and computer processing of the dataset collected during the 40thcruise of the R/V Akademik Vernadsky are presented. Accuracy

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Kazuhiko Masuda, Masayuki Sasaki, Tsutomu Takashima, and Hiroshi Ishida

1. Introduction Atmospheric aerosols play an important role in the earth radiation budget directly by scattering and absorbing solar and terrestrial radiation and indirectly by changing cloud properties. Accurate evaluation of the effects of the aerosols on the climate requires global information on aerosol properties such as optical thickness, size distribution, and refractive index. Ground-based measurements of the atmospheric aerosols by optical instruments such as sun photometers, aureole

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Christopher J. Merchant and Mark A. Saunders

dimensionless factor that scales the infrared optical thickness of aerosol for the three channels. An aerosol scale factor of 1.0 indicates channel-integrated optical thicknesses as given in Table 1 and represents aerosol typically present up to a year after a major volcanic eruptions, such as that of Mount Pinatubo in 1991 ( Lambert et al. 1993 ). The ratios of aerosol extinction to scattering cross section assumed are those chosen by Zavody et al. (1995) to represent aged volcanic aerosols. We use

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Pradeep Khatri, Tamio Takamura, Akihiro Yamazaki, and Yutaka Kondo

; Fioletov et al. 2002 ; Anton et al. 2008 ). The error induced by this assumption can be much larger at visible wavelengths than at UV wavelengths ( Grobner et al. 1996 ). The direct and diffuse irradiances observed by radiometers with horizontal surface detectors have been commonly used for aerosol research. For example, Petters et al. (2003) , Meloni et al. (2006) , Kassianov et al. (2007) , and Corr et al. (2009) retrieved key aerosol optical parameters, such as aerosol optical thickness ( τ

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D. D. Turner, R. A. Ferrare, L. A. Heilman Brasseur, W. F. Feltz, and T. P. Tooman

nitrogen data, and the extinction profile derived from the backscatter data using the smoothed S a data. The raw and smoothed extinction-to-backscatter ratio data for this case are shown in the lower-left panel of Fig. 4 . After extending the extinction profiles to the surface using the above technique, these profiles are then integrated from the surface to 7 km, or below cloud-base height, to provide aerosol optical thickness at 355 nm in the lower troposphere. Random error bars are shown on the 10

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Hyoun-Myoung Cho, Shaima L. Nasiri, Ping Yang, Istvan Laszlo, and Xuepeng “Tom” Zhao

satellite. Note that the reflectances in the solar bands have been solar zenith angle corrected and the brightness temperatures have been converted from radiances. The level-2 MODIS aerosol product (MYD04) retrievals of aerosol optical thickness (AOT) at 0.55 μ m using the dark target approach ( Remer et al. 2005 ) are used when comparing dust detection results. b. CALIPSO cloud and aerosol layer product The CALIPSO cloud and aerosol products used in this study are from the CALIPSO 5-km level-2

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Francesca Barnaba and Gian Paolo Gobbi

been shown (e.g., Kovalev 1995 ) that this assumption can lead to inaccurate estimates of the aerosol extinction, particularly when employed in turbid, nonhomogeneous, that is, real atmospheres. For example, analysis of the LITE measurements in Saharan dust conditions performed assuming two (boundary) values for the lidar ratio, R eb = 25 sr and R eb = 35 sr, led to maximum aerosol optical thickness AOT = 0.66 and AOT > 1, respectively ( Karyampudi et al. 1999 ). This example shows how crucial

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Dietrich Althausen, Detlef Müller, Albert Ansmann, Ulla Wandinger, Helgard Hube, Ernst Clauder, and Steffen Zörner

J. P. Meyzonette, Eds., Proc. SPIE, 1714, 209–219 . 10.1117/12.138527 Leiterer, U., A. Naebert, T. Naebert, and G. Alekseeva, 1995: A new star photometer developed for spectral aerosol optical thickness measurements in Lindenberg. Contrib. Atmos. Phys., 68, 133–141 . Makiyenko, E. V., and I. E. Naats, 1983: Determination of the optical properties of the stratospheric aerosols by multifrequency laser sensing. Izv. Atmos. Oceanic Phys., 19, 748–751 . McCormick, P., 1982: Lidar

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