• Anasimov, O., , and L. Fukshansky, 1992: Stochastic radiation in macroheterogeneous random optical media. J. Quant. Spectrosc. Radiat. Transfer, 48 , 169186.

    • Search Google Scholar
    • Export Citation
  • Barker, H W., 1996: A parameterization for computing grid-averaged solar fluxes for inhomogeneous marine boundary layer clouds. Part I: Methodology and homogeneous biases. J. Atmos. Sci., 53 , 22892303.

    • Search Google Scholar
    • Export Citation
  • Cahalan, R T., , W. Ridgway, , W J. Wiscombe, , T L. Bell, , and J B. Snider, 1994: The albedo of fractal stratocumulus clouds. J. Atmos. Sci., 51 , 24342455.

    • Search Google Scholar
    • Export Citation
  • Cairns, B., , A A. Lacis, , and B E. Carlson, 2000: Absorption within inhomogeneous clouds and its parameterization in general circulation models. J. Atmos. Sci., 57 , 700714.

    • Search Google Scholar
    • Export Citation
  • Clothiaux, E E., , T P. Ackerman, , G G. Mace, , K P. Moran, , R T. Marchand, , M A. Miller, , and B E. Martner, 2000: Objective determination of cloud heights and radar reflectivities using a combination of active remote sensors at the ARM CART sites. J. Appl. Meteor., 39 , 645665.

    • Search Google Scholar
    • Export Citation
  • Collins, W. D., and Coauthors, cited. 2003: Description of the NCAR Community Atmosphere Model (CAM2). [Available online at http://www.ccsm.ucar.edu/models/atm-cam/docs/cam2.0/description/index.html.].

  • Dong, X., , P. Minnis, , G G. Mace, , W L. Smith Jr., , M. Poellot, , R T. Marchand, , and A D. Rapp, 2002: Comparisons of stratus cloud properties deduced from surface, GOES, and aircraft data during the March 2000 ARM cloud IOP. J. Atmos. Sci., 59 , 32653284.

    • Search Google Scholar
    • Export Citation
  • Evans, K F., 1998: The spherical harmonic discrete ordinate method for three-dimensional atmospheric radiative transfer. J. Atmos. Sci., 55 , 429446.

    • Search Google Scholar
    • Export Citation
  • Gabriel, P M., , and K F. Evans, 1996: Simple radiative transfer methods for calculating domain-averaged solar fluxes in inhomogeneous clouds. J. Atmos. Sci., 53 , 858877.

    • Search Google Scholar
    • Export Citation
  • Kato, S., 2003: Computation of domain-averaged shortwave irradiance by a one-dimensional algorithm incorporating correlations between optical thickness and direct incident radiation. J. Atmos. Sci., 60 , 182193.

    • Search Google Scholar
    • Export Citation
  • Kobayashi, T., 1991: Reflected solar flux for horizontally inhomogeneous atmospheres. J. Atmos. Sci., 48 , 24362447.

  • Meador, W E., , and W R. Weaver, 1980: Two-stream approximations to radiative transfer in planetary atmospheres: A unified description of existing methods. J. Atmos. Sci., 37 , 630643.

    • Search Google Scholar
    • Export Citation
  • Oreopoulos, L., , and H W. Barker, 1999: Accounting for subgrid-scale cloud variability in a multi-layer 1D solar radiative transfer algorithm. Quart. J. Roy. Meteor. Soc., 125 , 301330.

    • Search Google Scholar
    • Export Citation
  • Pincus, R., , H W. Barker, , and J-J. Morcrette, 2003: A fast, flexible, approximate technique for computing radiative transfer in inhomogeneous cloud fields. J. Geophys. Res., 108 .4376, doi:10.1029/2002JD003322.

    • Search Google Scholar
    • Export Citation
  • Räisänen, P., , G A. Isaac, , H W. Barker, , and I. Gultepe, 2003: Solar radiative transfer for stratiform clouds with horizontal variations in liquid-water path and droplet effective radius. Quart. J. Roy. Meteor. Soc., 129 , 21352149.

    • Search Google Scholar
    • Export Citation
  • Randall, D., , M. Khairoutdinov, , A. Arakawa, , and W. Grabowski, 2003: Breaking the cloud parameterization deadlock. Bull. Amer. Meteor. Soc., 84 , 15471564.

    • Search Google Scholar
    • Export Citation
  • Stephens, G L., 1978: Radiation profiles in extended water clouds. II: Parameterization schemes. J. Atmos. Sci., 35 , 21232132.

  • Stephens, G L., 1988a: Radiative transfer through arbitrarily shaped optical media. Part I: A general method of solution. J. Atmos. Sci., 45 , 18181836.

    • Search Google Scholar
    • Export Citation
  • Stephens, G L., 1988b: Radiative transfer through arbitrarily shaped optical media. Part II: Group theory and simple closures. J. Atmos. Sci., 45 , 18371848.

    • Search Google Scholar
    • Export Citation
  • Stephens, G L., , P M. Gabriel, , and S-C. Tsay, 1991: Statistical radiative transport in one-dimensional media and its application to the terrestrial atmosphere. Transp. Theory Stat. Phys., 20 , 139175.

    • Search Google Scholar
    • Export Citation
  • Stephens, G L., , P M. Gabriel, , and P T. Partain, 2001: Parameterization of atmospheric radiative transfer. Part I: Validity of simple models. J. Atmos. Sci., 58 , 33913409.

    • Search Google Scholar
    • Export Citation
  • Stephens, G L., and Coauthors, 2002: The CloudSat mission and the A-Train: A new dimension of space-based observations of clouds and precipitation. Bull. Amer. Meteor. Soc., 83 , 17711790.

    • Search Google Scholar
    • Export Citation
  • Stephens, G L., , N B. Wood, , and P M. Gabriel, 2004: An assessment of the parameterization of subgrid-scale cloud effects on radiative transfer. Part I: Vertical overlap. J. Atmos. Sci., 61 , 715732.

    • Search Google Scholar
    • Export Citation
  • Zuidema, P., , and K F. Evans, 1998: On the validity of the independent pixel approximation for boundary layer clouds observed during ASTEX. J. Geophys. Res., 103 , 60596074.

    • Search Google Scholar
    • Export Citation
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An Assessment of the Parameterization of Subgrid-Scale Cloud Effects on Radiative Transfer. Part II: Horizontal Inhomogeneity

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  • 1 Department of Atmospheric Science, Colorado State University, Fort Collins, Colorado
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Abstract

The role of horizontal inhomogeneity in radiative transfer through cloud fields is investigated within the context of the two-stream approximation. Spatial correlations between cloud optical properties and the radiance field are introduced in the three-dimensional radiative transfer equation and lead to a two-stream model in which the correlations are represented by parameterizations. The behavior of the model is examined using simple single-layer single-column atmospheres. Positive correlations between extinction or scattering and the radiance field are shown to decrease transmission, increase reflection, and increase absorption within inhomogeneous media. The parameterization is used to evaluate the characteristics of inhomogeneous cloud fields observed by radar and lidar over a number of different locations and seasons, revealing that shortwave transfer is generally characterized by negative correlations between extinction and radiance, while longwave transfer is characterized by positive correlations. The results from this characterization are applied to the integration of an atmospheric general circulation model. Model surface temperatures are significantly affected, largely in response to changes in downwelling radiative fluxes at the surface induced by changes in cloud cover and water vapor distributions.

Corresponding author address: Norman B. Wood, Department of Atmospheric Science, Colorado State University, Fort Collins, CO 80523. Email: norm@atmos.colostate.edu

Abstract

The role of horizontal inhomogeneity in radiative transfer through cloud fields is investigated within the context of the two-stream approximation. Spatial correlations between cloud optical properties and the radiance field are introduced in the three-dimensional radiative transfer equation and lead to a two-stream model in which the correlations are represented by parameterizations. The behavior of the model is examined using simple single-layer single-column atmospheres. Positive correlations between extinction or scattering and the radiance field are shown to decrease transmission, increase reflection, and increase absorption within inhomogeneous media. The parameterization is used to evaluate the characteristics of inhomogeneous cloud fields observed by radar and lidar over a number of different locations and seasons, revealing that shortwave transfer is generally characterized by negative correlations between extinction and radiance, while longwave transfer is characterized by positive correlations. The results from this characterization are applied to the integration of an atmospheric general circulation model. Model surface temperatures are significantly affected, largely in response to changes in downwelling radiative fluxes at the surface induced by changes in cloud cover and water vapor distributions.

Corresponding author address: Norman B. Wood, Department of Atmospheric Science, Colorado State University, Fort Collins, CO 80523. Email: norm@atmos.colostate.edu

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