• 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
  • Barker, H. W., , and P. Räisänen, 2004: Neglect by GCMs of subgrid-scale horizontal variations in cloud-droplet effective radius: A diagnostic radiative analysis. Quart. J. Roy. Meteor. Soc., 130 , 19051920.

    • Search Google Scholar
    • Export Citation
  • Cahalan, R. F., , 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
  • Chou, M-D., , M. J. Suarez, , C-H. Ho, , M. M-H. Yan, , and K-T. Lee, 1998: Parameterizations for cloud overlapping and shortwave single-scattering properties for use in general circulation and cloud ensemble models. J. Climate, 11 , 202214.

    • Search Google Scholar
    • Export Citation
  • Derber, J. C., , D. F. Parrish, , and S. J. Lord, 1991: The new global operational analysis system at the National Meteorological Center. Wea. Forecasting, 6 , 538547.

    • Search Google Scholar
    • Export Citation
  • Harshvardhan, , and D. A. Randall, 1985: Comments on “The parameterization of radiation for numerical weather prediction and climate models.”. Mon. Wea. Rev., 113 , 18321833.

    • Search Google Scholar
    • Export Citation
  • Hu, Y. X., , and K. Stamnes, 1993: An accurate parameterization of the radiative properties of water clouds suitable for use in climate models. J. Climate, 6 , 728742.

    • Search Google Scholar
    • Export Citation
  • Khairoutdinov, M., , D. A. Randall, , and C. DeMott, 2005: Simulations of the atmospheric general circulation using a cloud-resolving model as a superparameterization of physical processes. J. Atmos. Sci., 62 , 21362154.

    • Search Google Scholar
    • Export Citation
  • Kiehl, J. T., , and K. E. Trenberth, 1997: Earth’s annual global mean energy budget. Bull. Amer. Meteor. Soc., 78 , 197208.

  • King, M. D., and Coauthors, 2003: Cloud and aerosol properties, precipitable water, and profiles of temperature and water vapor from MODIS. IEEE Trans. Geosci. Remote Sens., 41 , 442458.

    • Search Google Scholar
    • Export Citation
  • Moody, E. G., , M. D. King, , S. Platnick, , C. B. Schaaf, , and F. Gao, 2005: Spatially complete global spectral surface albedos: Value-added datasets derived from Terra MODIS land products. IEEE Trans. Geosci. Remote Sens., 43 , 144158.

    • Search Google Scholar
    • Export Citation
  • Oreopoulos, L., , and R. Davies, 1998: Plane parallel albedo biases from satellite observations. Part I: Dependence on resolution and other factors. J. Climate, 11 , 919932.

    • Search Google Scholar
    • Export Citation
  • Oreopoulos, L., , and R. F. Cahalan, 2005: Cloud inhomogeneity from MODIS. J. Climate, 18 , 51105124.

  • Oreopoulos, L., , M-D. Chou, , M. Khairoutdinov, , H. W. Barker, , and R. F. Cahalan, 2004: Performance of Goddard Earth Observing System GCM Column Radiation Models under heterogeneous cloud conditions. Atmos. Res., 72 , 365382.

    • Search Google Scholar
    • Export Citation
  • Pincus, R., , S. A. McFarlane, , and S. A. Klein, 1999: Albedo bias and the horizontal variability of clouds in subtropical marine boundary layers: Observations from ships and satellites. J. Geophys. Res., 104 , 61836191.

    • 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
  • Räisänen, P., , H. W. Barker, , M. F. Khairoutdinov, , J. Li, , and D. A. Randall, 2004: Stochastic generation of subgrid-scale cloudy columns for large-scale models. Quart. J. Roy. Meteor. Soc., 130 , 20472067.

    • Search Google Scholar
    • Export Citation
  • Rossow, W. B., , C. Delo, , and B. Cairns, 2002: Implications of the observed mesoscale variations of clouds for the Earth’s radiation budget. J. Climate, 15 , 557585.

    • Search Google Scholar
    • Export Citation
  • Scheirer, R., , and A. Macke, 2003: Cloud inhomogeneity and broadband solar fluxes. J. Geophys. Res., 108 .4599, doi:10.1029/ 2002JD003321.

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

    • Search Google Scholar
    • Export Citation
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The Plane-Parallel Albedo Bias of Liquid Clouds from MODIS Observations

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  • 1 Joint Center for Earth Systems Technology, University of Maryland, Baltimore County, Baltimore, and Laboratory for Atmospheres, NASA Goddard Space Flight Center, Greenbelt, Maryland
  • | 2 Laboratory for Atmospheres, NASA Goddard Space Flight Center, Greenbelt, and Joint Center for Earth Systems Technology, University of Maryland, Baltimore County, Baltimore, Maryland
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Abstract

The authors present the global plane-parallel shortwave albedo bias of liquid clouds for two months, July 2003 and January 2004. The cloud optical properties necessary to perform the bias calculations come from the operational Moderate Resolution Imaging Spectroradiometer (MODIS) Terra and MODIS Aqua level-3 datasets. These data, along with ancillary surface albedo and atmospheric information consistent with the MODIS retrievals, are inserted into a broadband shortwave radiative transfer model to calculate the fluxes at the atmospheric column boundaries. The plane-parallel homogeneous (PPH) calculations are based on the mean cloud properties, while independent column approximation (ICA) calculations are based either on 1D histograms of optical thickness or joint 2D histograms of optical thickness and effective radius. The (positive) PPH albedo bias is simply the difference between PPH and ICA albedo calculations. Two types of biases are therefore examined: 1) the bias due to the horizontal inhomogeneity of optical thickness alone (the effective radius is set to the grid mean value) and 2) the bias due to simultaneous variations of optical thickness and effective radius as derived from their joint histograms. The authors find that the global bias of albedo (liquid cloud portion of the grid boxes only) is ∼+0.03, which corresponds to roughly 8% of the global liquid cloud albedo and is only modestly sensitive to the inclusion of horizontal effective radius variability and time of day, but depends strongly on season and latitude. This albedo bias translates to ∼3–3.5 W m−2 of bias (stronger negative values) in the diurnally averaged global shortwave cloud radiative forcing, assuming homogeneous conditions for the fraction of the grid box not covered by liquid clouds; zonal values can be as high as 8 W m−2. Finally, the (positive) broadband atmospheric absorptance bias is about an order of magnitude smaller than the albedo bias. The substantial magnitude of the PPH bias underlines the importance of predicting subgrid variability in GCMs and accounting for its effects on cloud–radiation interactions.

Corresponding author address: Lazaros Oreopoulos, NASA Goddard Space Flight Center, Code 613.2, Greenbelt, MD 20771. Email: lazaros@climate.gsfc.nasa.gov

Abstract

The authors present the global plane-parallel shortwave albedo bias of liquid clouds for two months, July 2003 and January 2004. The cloud optical properties necessary to perform the bias calculations come from the operational Moderate Resolution Imaging Spectroradiometer (MODIS) Terra and MODIS Aqua level-3 datasets. These data, along with ancillary surface albedo and atmospheric information consistent with the MODIS retrievals, are inserted into a broadband shortwave radiative transfer model to calculate the fluxes at the atmospheric column boundaries. The plane-parallel homogeneous (PPH) calculations are based on the mean cloud properties, while independent column approximation (ICA) calculations are based either on 1D histograms of optical thickness or joint 2D histograms of optical thickness and effective radius. The (positive) PPH albedo bias is simply the difference between PPH and ICA albedo calculations. Two types of biases are therefore examined: 1) the bias due to the horizontal inhomogeneity of optical thickness alone (the effective radius is set to the grid mean value) and 2) the bias due to simultaneous variations of optical thickness and effective radius as derived from their joint histograms. The authors find that the global bias of albedo (liquid cloud portion of the grid boxes only) is ∼+0.03, which corresponds to roughly 8% of the global liquid cloud albedo and is only modestly sensitive to the inclusion of horizontal effective radius variability and time of day, but depends strongly on season and latitude. This albedo bias translates to ∼3–3.5 W m−2 of bias (stronger negative values) in the diurnally averaged global shortwave cloud radiative forcing, assuming homogeneous conditions for the fraction of the grid box not covered by liquid clouds; zonal values can be as high as 8 W m−2. Finally, the (positive) broadband atmospheric absorptance bias is about an order of magnitude smaller than the albedo bias. The substantial magnitude of the PPH bias underlines the importance of predicting subgrid variability in GCMs and accounting for its effects on cloud–radiation interactions.

Corresponding author address: Lazaros Oreopoulos, NASA Goddard Space Flight Center, Code 613.2, Greenbelt, MD 20771. Email: lazaros@climate.gsfc.nasa.gov

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