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Laura Mihai and Sabina Stefan

( Vardavas and Taylor 2007 ). It is therefore very important to understand the aerosols effects in the radiative transfer phenomena and to obtain their optical properties with maximum accuracy, both in real time and over the largest possible area of the earth. The optical properties that offer a thorough picture of the aerosol size distribution and mass are the aerosol optical depth (AOD), the Ångström exponent, and the fraction of fine-mode aerosol. In this paper, the results of the statistical analysis

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Xiaodong Liu, Shouguo Ding, Lei Bi, and Ping Yang

1. Introduction Ice clouds remain one of the key uncertainty sources in the study of the atmospheric radiation budget and atmospheric remote sensing ( Liou 1986 ; Lynch et al. 2002 ; Wendisch et al. 2007 ; Minnis et al. 1993a , b ; Baum et al. 2000 , 2005 ; Baran 2009 , and references cited therein). These clouds also pose a challenge to atmospheric radiative transfer and remote sensing studies. As the optical properties of ice crystals are fundamental to quantifying the radiative

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John E. Yorks, Dennis L. Hlavka, William D. Hart, and Matthew J. McGill

their optical and physical properties is necessary. A combination of both in situ and remote sensing measurements is necessary for this climatology, because remote sensing instruments can provide global data in remote regions with high temporal and spatial resolution that are not accessible using in situ measurements ( Wang and Sassen 2001 ). The launches of the Geoscience Laser Altimeter System (GLAS; Spinhirne et al. 2005 ) in January 2003 and the Cloud–Aerosol Lidar and Infrared Pathfinder

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Michael E. Feinholz, Stephanie J. Flora, Mark A. Yarbrough, Keith R. Lykke, Steven W. Brown, B. Carol Johnson, and Dennis K. Clark

1. Introduction The optical properties of seawater reflect its composition. Under natural illumination from sunlight, radiometric measurements of the light leaving the ocean contain information about the nature and concentration of dissolved and suspended materials. The optical properties of the ocean can be related to meaningful physical and biogeochemical data products such as the concentration of phytoplankton chlorophyll- a through bio-optical algorithms. Quantitative measurements of

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Wayne H. Slade, Emmanuel Boss, Giorgio Dall’Olmo, M. Rois Langner, James Loftin, Michael J. Behrenfeld, Collin Roesler, and Toby K. Westberry

optical absorption, attenuation, and backscattering coefficients. These quantities can be used to validate remotely sensed optical parameters and to estimate biomass and, using variable fluorescence, the physiological state of phytoplankton (e.g., Mueller et al. 2003 ; Behrenfeld and Boss 2003 ), as well as to provide constraints on particulate and dissolved pools and properties in ecosystem models (e.g., Fujii et al. 2007 ). Spectral particulate absorption and attenuation have also been used to

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Bart De Paepe and Steven Dewitte

often appeared as a gap on the current aerosol retrievals, since most aerosol retrieval algorithms use the solar channels that are not suited to work over bright reflecting surfaces, such as the desert. Algorithms that use other parts of the spectrum, such as the ultraviolet ( Hsu et al. 2004 ), help to overcome these problems. In addition to the spectral information, there are algorithms that use angular information to retrieve the aerosol optical properties. The Multiangle Imaging

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David Antoine, André Morel, Edouard Leymarie, Amel Houyou, Bernard Gentili, Stéphane Victori, Jean-Pierre Buis, Nicolas Buis, Sylvain Meunier, Marius Canini, Didier Crozel, Bertrand Fougnie, and Patrice Henry

which photons are simply diverted from their initial direction of propagation. These phenomena are described by coefficients that belong to the “inherent” optical properties (IOPs; Preisendorfer 1961 ). The way these processes alter the radiant field is described by the radiative transfer equation (RTE) ( Mobley 1994 ). To describe the radiant field inside a scattering/absorbing medium, like a water body, the spectral radiance ( L ) is the fundamental radiometric quantity (units: W m −2 sr −1 nm

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K. M. Markowicz, P. J. Flatau, A. E. Kardas, J. Remiszewska, K. Stelmaszczyk, and L. Woeste

1. Introduction The role of atmospheric aerosols in modifying the radiation budget of the earth–atmosphere climate system is being increasingly understood and recognized ( Hansen et al. 1997 ; Haywood et al. 1999 ; Ramanathan et al. 2001 ). There are still large uncertainties of the aerosol radiative forcing on regional scales ( Houghton et al. 2001 ) because of the lack of sufficient knowledge of aerosols’ optical, physical, and chemical properties and their large spatial and temporal

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H. Wang, R. T. Pinker, P. Minnis, and M. M. Khaiyer

( Ramanathan 1986 ; Pinker and Laszlo 1992 ; Li and Leighton 1993 ; Stephens et al. 1994 ; Gupta et al. 1999 ; Mueller et al. 2004 ; Raschke et al. 1991 ; Rigollier et al. 2004 ; Whitlock et al. 1995 ; Lefèvre et al. 2007 ). Most models have been designed for use with a particular satellite and, frequently, cloud optical properties are inferred from a single visible channel. The use of multichannel information is expected to provide a more accurate description of cloud optical properties and

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W. J. Koshak

1. Introduction The study by Koshak (2010) showed that the distributions of ground and cloud flash optical characteristics, as seen from the Optical Transient Detector (OTD), overlap appreciably. Therefore, space-based flash-type discrimination (on a flash-by-flash basis) is fundamentally difficult. However, Koshak (2010) also indicated that the mean values of the optical characteristics for ground and cloud flashes are distinct, so that an analysis of a sample of N flashes could possibly

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