A Radiative Parameterization of Stratocumulus Cloud Fields

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  • 1 Institute of Atmospheric sciences, South,Dakota School of Mines and Technology, Rapid City, SD 57701
  • | 2 Atmospheric Sciences Division NASA Langley Research Center, Hampton, VA 23665
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Abstract

A parameterization scheme is presented which allows the calculation of radiative reflected fluxes from a stratocumulus cloud field. The scheme is based upon plane-parallel calculations, such as delta-Eddington, and a simple procedure is outlined by which the plane-parallel fluxes may be transformed to those of the broken cloud case. This parameterization scheme has been tested for optical thicknesses ranging from τ=3 to 49, solar zenith angles ranging from θ0 = 0° to 72.5°, and all values of cloud cover. Plane-parallel calculations become increasingly more accurate as optical depth decreases. This suggests that calculations including broken cloudiness effects such as shadowing are probably unnecessary in thin cirrus or aerosol layers over water.

Abstract

A parameterization scheme is presented which allows the calculation of radiative reflected fluxes from a stratocumulus cloud field. The scheme is based upon plane-parallel calculations, such as delta-Eddington, and a simple procedure is outlined by which the plane-parallel fluxes may be transformed to those of the broken cloud case. This parameterization scheme has been tested for optical thicknesses ranging from τ=3 to 49, solar zenith angles ranging from θ0 = 0° to 72.5°, and all values of cloud cover. Plane-parallel calculations become increasingly more accurate as optical depth decreases. This suggests that calculations including broken cloudiness effects such as shadowing are probably unnecessary in thin cirrus or aerosol layers over water.

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