Scattering of solar radiation as a function of cloud dimensions and orientation

Aida, Masaru

doi:10.1016/0022-4073(77)90109-1

Cited by 63 publications

(22 citation statements)

References 2 publications

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“…In summary, Fig. 1 shows that our Monte Carlo scheme is in agreement with previous work (Aida, 1977). and it will be used in the following to derive a parameterization for the influence of cloud geometry or macrostructure on radiative properties.…”

Section: The Monte Carlo Simulationsupporting

confidence: 90%

On the parameterization of the radiative properties of broken clouds

Schmetz

1984

Tellus A: Dynamic Meteorology and Oceanography

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A onedimensional radiative transfer scheme is presented which accounts for the efTects of broken cloud in the solar and infrared rdition field. The fractional cloud amount is explicitly considered in the two-stream model by treating clouds as the boundary condition between two adjacent atmospheric layers. The scheme accounts for absorption and scattering by gases and aerosols assuming realistic atmospheres. The radiative properties of broken clouds are included in a parameterized form making use of results from three-dimensional radiative transfer models. The radiative characteristics of a cloud field are represented by an average finite cloud whose size or optical thickness grows with increasing cloud amount. This growth is described by a simple mathematical model, and its use yields qualitative agreement between model results and observations for solar radiation.The scheme is then applied to calculate the net radiative effect of broken cloud. Since thecloud size growth with cloud amount implies a non-linear relation between the fractional cloud amount and the radiative properties of the cloud field, the net radiative eff'ect of cloud depends on cloud mount. The idealized model shows that the albedo efTcct (increase of solar reflection with cloud amount) of broken cloud is smaller than that of a plane-paralkl cloud for cloud amounts less than about 0.7. while the opposite is true for larger cloud amounts. The greenhouse efTcct (reduction of the outgoing long-wave flux) of broken cloud is larger than that of a plane-paralkl cloud for small cloud amount and smaller for large cloud amount.An application of the radiation scheme to compute bispectral curves of visibk albedo versus thermal brightness temperature shows that broken cloud layers and unbroken layers with variable optical depths show a similar shape of the bispectral curve.

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Section: The Monte Carlo Simulationsupporting

confidence: 90%

On the parameterization of the radiative properties of broken clouds

Schmetz

1984

Tellus A: Dynamic Meteorology and Oceanography

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“…their reflectance therefore deserves more study. Concerning the cloud-cloud interactions, the problem was first addressed by Aida [1976], who pointed out that surrounding clouds did not alter the cloud reflectance for distances larger than about 5 times the cloud horizontal dimension. Obviously, interactions may be quite large for high cloud cover, but the question is the resulting modification of the reflectance.…”

Section: The Indirect Problem: Directional Effects Of Brokenness Becmentioning

confidence: 99%

The influence of clouds on radiation: A climate‐modeling perspective

Fouquart¹,

Buriez²,

Herman³

et al. 1990

Reviews of Geophysics

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The influence of clouds on the radiation field is reviewed from the point of view of their representation in climate models. Such models are expected to include, in the very near future, condensed water as an additional prognostic variable. We examine how simple parameterizations based on the liquid water content can realistically simulate the radiation field. We focus on the extended low‐level clouds for which numerous results of simultaneous radiation and microphysics measurements are available. Particular attention is given to the shortwave absorption in cloud layers because theoretically calculated absorptances are generally weaker than those observed. The problem of the broken field is approached in terms of a relationship between the actual cloud cover and the equivalent cloud cover which gives the same irradiances but using the plane‐parallel formalism.

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“…In this paper we estimate how the urban albedo changes as a function of urban geometrical structures. In the present calculation the photo trajectories were simulated by a Monte-Carlo method as used in the radiation problems in clouds (e.g., Aida, 1977). Surface structures producing the minimum or maximum albedo are also inferred from the model calculations.…”

Section: Introductionmentioning

confidence: 99%

Urban albedo as a function of the urban structure ? A two-dimensional numerical simulation

Aida

Gotoh

1982

Boundary-Layer Meteorol

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Urban albedo change as a function of urban geometrical structure has been examined by using a two-dimensional urban block-canyon array model. The complex multiple reflections of incident photons in the urban canyon are simulated by using a Monte-Carlo method. The photons are tracked until they leave the canyon or are completely absorbed. In the model, the direct and diffuse components of incident solar radiation are introduced and the specular and isotropic reflection characteristics are considered for the relevant urban surfaces. The result shows that the urban albedo decreases as the urban irregularity increases as indicated by the model experiment of Aida (1982). The dependence of albedo on the incident solar zenith angle observed in the experiment is also confirmed for various urban models.As an application, some actual urban structures in the Marunouchi area in Tokyo are examined. Urban planning for absorption and reflection of solar radiation in urban areas is also discussed based on the analysis of the change in albedo with canyon dimensions and solar zenith angle.

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Scattering of solar radiation as a function of cloud dimensions and orientation

Cited by 63 publications

References 2 publications

On the parameterization of the radiative properties of broken clouds

On the parameterization of the radiative properties of broken clouds

The influence of clouds on radiation: A climate‐modeling perspective

Urban albedo as a function of the urban structure ? A two-dimensional numerical simulation

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