Stephens. Optical Properties Of Eight Water Cloud Types

Optical Propertiesof Eight Water Cloud Types GnnEuEL. SrEpsexs DIVISION OF ATMOSPHERIC PHYSICS TECHMCAL PAPER NO. 36 COMMONWEALTH SCIENTIFIC AND INDUSTRIAL RESEARCH ORGANIZATION. AUSTRALIA 1979 CSIRO Aust. Div. Atmog Phys. Teck. Pap. No. 36, 1-35 (1979) Optical Propertiesof Eight Water Cloud Types Grueme L. Stephens Vic. 3195. Physics, CSIRO,StationStreet,Aspendale, Divisionof Atmospheric Abstract for eightdifferentwatercloudtypesusingupto-date areprescribed Mie singlescatteringparameters and consistentvaluesof liquid water refractiveindex. The main resultsare presentedin tabular rangingfrom 0.3 prmto 200 pm. Single form for eachcloudtype for 110 differentwavelengths scatteringalbedo,volumeextinctioncoefficientand asymmetryfactor are amongthe properties radiativetransferschemes presented.Thesequantitiescan be incorporatedinto multiplescattering which are usedto calculatethe grossradiativepropertiesof clouds. The interaction of an electromagneticwave with an absorbingsphereis described by Mie theory and is adequatelydiscussedin Van de Hulst's classicbook (Van de Hulst, 1957). Unfortunately, this book was published before the widespreaduse of modern computers. Since that time, severalnumerical techniqueshave been introduced to effect fast and accuratesolutions. The three important single scatteringparametersdetermined from Mie theory, and ultimately used in multiple scatteringmodels, are the single scatteringalbedo (ejo), the asymmetry parameter characterizing the angular distribution of scattering ((cos0)) and the Mie extinction efficiency factor (Q"*1) from which the extinction coefficient and optical depth of the medium is determined. Previouscomputations of Ois, (cosO) and Q"*1 have been summarizedby Feigelson(1964) and Herman (L962). Yamamoto et al. (197L) listed a number of Mie parametersfor three polydisperse(i.e. many sized particle) cloud models for wavelengths). ) 5 pm. There have been a large number of computations of Mie single scatteringparametersover the past decadeor so. However, most of the results listed pertain to monodisperse (i.e. single sized particle) media. There are few computations of 66 for L ( I pm and calculationsof (cos0) for all wavelengthsare lacking in detail. Irvine and Pollack (1968) presenteda detailed study of 66 for ). ) 1 pm using single particles of specific radius and presented(cos0) for an ice sphere of radius 10 pm illuminated by radiation of \ ) I pm. In this paper singlescatteringparametersare presented for a number of different water cloud types pgssessingspecifieddroplet size distributions and for wavelengthsranging from the ultraviolet to the far infrared. The computations describedin this paper illustrate the behaviour of the Mie parametersfor three of the eight water cloud models introduced in Table 1. More specific and detailed results appearin the