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contributor authorKing, Michael D.
date accessioned2017-06-09T14:27:25Z
date available2017-06-09T14:27:25Z
date copyright1987/07/01
date issued1987
identifier issn0022-4928
identifier otherams-19564.pdf
identifier urihttp://onlinelibrary.yabesh.ir/handle/yetl/4155694
description abstractA method is presented for determining the scaled optical thickness of clouds from reflected solar radiation measurements. The procedure compares measurements of the reflection function with asymptotic expressions for the reflection function of optically thick layers. Analytic formulas are derived which explicitly show the dependence of the reflection and transmission functions of nonabsorbing atmospheres, on cloud optical thickness (τc), ground albedo (Ag) and asymmetry factor (g). For nonconservative atmospheres, the dependence of the reflection function on single scattering albedo (?0) and asymmetry factor are contained implicitly in the asymptotic functions and constants. These asymptotic expressions for both conservative and nonconservative atmosphere are shown to be valid when the scaled optical thickness (1?g)τc≥??1.45, corresponding to clouds of optical thickness τc≥??9. By utilizing the asymptotic expression for the reflection function of an optically thick, conservatively scattering atmosphere. a simple expression is obtained relating the measured reflection function to scaled optical thickness. This expression shows that the ground albedo produces a constant bias in the derived optical thickness, regardless of the value of the measured reflection function. High-resolution images of the reflection function of clouds have been obtained with a multichannel scanning radiometer operated from a high-altitude aircraft. An image of the reflection function of clouds obtained from a stratiform cloud system in central Oklahoma is analyzed using two different phase functions. Results show that details of the single scattering phase function have an impact on the derived optical thickness, although the dominant influence is the cloud asymmetry factor which appears explicitly in the analysis.
publisherAmerican Meteorological Society
titleDetermination of the Scaled Optical Thickness of Clouds from Reflected Solar Radiation Measurements
typeJournal Paper
journal volume44
journal issue13
journal titleJournal of the Atmospheric Sciences
identifier doi10.1175/1520-0469(1987)044<1734:DOTSOT>2.0.CO;2
journal fristpage1734
journal lastpage1751
treeJournal of the Atmospheric Sciences:;1987:;Volume( 044 ):;issue: 013
contenttypeFulltext


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