Parameterization of the radiative properties of cirrus clouds

Journal Article · Thu Jul 01 04:00:00 EDT 1993 · Journal of the Atmospheric Sciences; (United States)

DOI:https://doi.org/10.1175/1520-0469(1993)050<2008:POTRPO>2.0.CO;2· OSTI ID:6245753

Fu, Qiang; Liou, K N ^[1]

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1. Univ. of Utah, Salt Lake City (United States)

A new approach for parameterization of the broadband solar and infrared radiative properties of ice clouds has been developed. This parameterization scheme integrates in a coherent manner the [delta]-four-stream approximation for radiative transfer, the correlated K-distribution method for nongray gaseous absorption, and the scattering and absorption properties of hexagonal ice crystals. A mean effective size is used, representing an area-weighted mean crystal width, to account for the ice crystal size distribution with respect to radiative calculations. Based on physical principles, the basic single-scattering properties of ice crystals can be parameterization using third-degree polynomials in terms of the mean effective size. The results computed from a light scattering program with a geometric ray-tracing program for size parameters larger than 30 and the exact spheroid solution for size parameters less than 30 are used. The computations are carried out for 11 observed ice crystal size distributions and cover the entire solar and thermal infrared spectra. Parameterization of the single-scattering properties is shown to provide an accuracy within about 1%. Comparisons have been carried out between results computed from the model and those obtained during the 1986 cirrus FIRE IFO. The model results can be used to interpret the observed IR emissivities and solar albedo involving cirrus clouds. The scheme has been employed to investigate the radiative effect of ice crystal size distributions. The effects of ice crystal size distribution in the context of IR greenhouse versus solar albedo effects involving cirrus clouds are presented. The present scheme for radiative transfer involving cirrus clouds is suited for incorporation in numerical models to study the climatic effects of cirrus clouds, as well as to investigate interactions and feedbacks between cloud microphysics and radiation. 36 refs., 10 figs., 5 tabs.

• OSTI ID: 6245753
• Journal Information: Journal of the Atmospheric Sciences; (United States), Journal Name: Journal of the Atmospheric Sciences; (United States) Vol. 50:13; ISSN JAHSAK; ISSN 0022-4928
• Country of Publication: United States
• Language: English

Related Subjects

54 ENVIRONMENTAL SCIENCES
540110*
ABSORPTION
ALBEDO
CLIMATIC CHANGE
CLOUDS
COOLING
CRYSTALS
ELECTROMAGNETIC RADIATION
ENERGY ABSORPTION
ENERGY TRANSFER
GREENHOUSE EFFECT
HEAT TRANSFER
HEATING RATE
ICE
INFRARED RADIATION
LIGHT SCATTERING
PARAMETRIC ANALYSIS
PHYSICAL PROPERTIES
RADIATIONS
RADIATIVE COOLING
SCATTERING
SOLAR RADIATION
SORPTION
STELLAR RADIATION
THERMODYNAMIC PROPERTIES