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    Small-Scale Drop Size Variability: Impact on Estimation of Cloud Optical Properties

    Source: Journal of the Atmospheric Sciences:;2005:;Volume( 062 ):;issue: 007::page 2555
    Author:
    Knyazikhin, Y.
    ,
    Myneni, R. B.
    ,
    Marshak, A.
    ,
    Wiscombe, W. J.
    ,
    Larsen, M. L.
    ,
    Martonchik, J. V.
    DOI: 10.1175/JAS3488.1
    Publisher: American Meteorological Society
    Abstract: Most cloud radiation models and conventional data processing techniques assume that the mean number of drops of a given radius is proportional to volume. The analysis of microphysical data on liquid water drop sizes shows that, for sufficiently small volumes, this proportionality breaks down; the number of cloud drops of a given radius is instead proportional to the volume raised to a drop size?dependent nonunit power. The coefficient of proportionality, a generalized drop concentration, is a function of the drop size. For abundant small drops the power is unity as assumed in the conventional approach. However, for rarer large drops, it falls increasingly below unity. This empirical fact leads to drop clustering, with the larger drops exhibiting a greater degree of clustering. The generalized drop concentration shows the mean number of drops per cluster, while the power characterizes the occurrence frequency of clusters. With a fixed total number of drops in a cloud, a decrease in frequency of clusters is accompanied by a corresponding increase in the generalized concentration. This initiates a competing process missed in the conventional models: an increase in the number of drops per cluster enhances the impact of rarer large drops on cloud radiation while a decrease in the frequency suppresses it. Because of the nonlinear relationship between the number of clustered drops and the volume, these two opposite tendencies do not necessarily compensate each other. The data analysis suggests that clustered drops likely have a stronger radiative impact compared to their unclustered counterpart; ignoring it results in underestimation of the contribution from large drops to cloud horizontal optical path.
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      Small-Scale Drop Size Variability: Impact on Estimation of Cloud Optical Properties

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    http://yetl.yabesh.ir/yetl1/handle/yetl/4218037
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    contributor authorKnyazikhin, Y.
    contributor authorMyneni, R. B.
    contributor authorMarshak, A.
    contributor authorWiscombe, W. J.
    contributor authorLarsen, M. L.
    contributor authorMartonchik, J. V.
    date accessioned2017-06-09T16:52:20Z
    date available2017-06-09T16:52:20Z
    date copyright2005/07/01
    date issued2005
    identifier issn0022-4928
    identifier otherams-75675.pdf
    identifier urihttp://onlinelibrary.yabesh.ir/handle/yetl/4218037
    description abstractMost cloud radiation models and conventional data processing techniques assume that the mean number of drops of a given radius is proportional to volume. The analysis of microphysical data on liquid water drop sizes shows that, for sufficiently small volumes, this proportionality breaks down; the number of cloud drops of a given radius is instead proportional to the volume raised to a drop size?dependent nonunit power. The coefficient of proportionality, a generalized drop concentration, is a function of the drop size. For abundant small drops the power is unity as assumed in the conventional approach. However, for rarer large drops, it falls increasingly below unity. This empirical fact leads to drop clustering, with the larger drops exhibiting a greater degree of clustering. The generalized drop concentration shows the mean number of drops per cluster, while the power characterizes the occurrence frequency of clusters. With a fixed total number of drops in a cloud, a decrease in frequency of clusters is accompanied by a corresponding increase in the generalized concentration. This initiates a competing process missed in the conventional models: an increase in the number of drops per cluster enhances the impact of rarer large drops on cloud radiation while a decrease in the frequency suppresses it. Because of the nonlinear relationship between the number of clustered drops and the volume, these two opposite tendencies do not necessarily compensate each other. The data analysis suggests that clustered drops likely have a stronger radiative impact compared to their unclustered counterpart; ignoring it results in underestimation of the contribution from large drops to cloud horizontal optical path.
    publisherAmerican Meteorological Society
    titleSmall-Scale Drop Size Variability: Impact on Estimation of Cloud Optical Properties
    typeJournal Paper
    journal volume62
    journal issue7
    journal titleJournal of the Atmospheric Sciences
    identifier doi10.1175/JAS3488.1
    journal fristpage2555
    journal lastpage2567
    treeJournal of the Atmospheric Sciences:;2005:;Volume( 062 ):;issue: 007
    contenttypeFulltext
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    DSpace software copyright © 2002-2015  DuraSpace
    نرم افزار کتابخانه دیجیتال "دی اسپیس" فارسی شده توسط یابش برای کتابخانه های ایرانی | تماس با یابش
    yabeshDSpacePersian