Radiative Transfer in Water Clouds in the Infrared Region
01 Mar 1970-Journal of the Atmospheric Sciences (American Meteorological Society)-Vol. 27, Iss: 2, pp 282-292
TL;DR: In this paper, the problem of diffuse reflection, transmission and emission of infrared radiation by water clouds is investigated in the wavelength region from 5-50 µm, where the drop-size distribution is assumed to be that of altostratus measured by Diem.
Abstract: The problem of diffuse reflection, transmission and emission of infrared radiation by water clouds is investigated in the wavelength region from 5–50 μ. The drop-size distribution of clouds is assumed to be that of altostratus measured by Diem. The phase function and other optical properties of the clouds are estimated from the value of the refractive index of water proposed by Pontier and Dechambenoy. Radiative processes due to both cloud droplets and water vapor in the cloud are taken into account, and a method of averaging the solution over a spectral interval including a number of absorption lines is developed.
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TL;DR: A radiative transfer method for treating nongray gaseous absorption and thermal emission in vertically inhomogeneous multiple scattering atmospheres is described in this paper, where probability density distributions of absorption coefficient strength are derived from line-by-line calculations to construct line-By-line and band model based k distributions.
Abstract: A radiative transfer method for treating nongray gaseous absorption and thermal emission in vertically inhomogeneous multiple scattering atmospheres is described. Probability density distributions of absorption coefficient strength are derived from line-by-line calculations to construct line-by-line and band model based k distributions. The monotonic ordering of absorption coefficient strengths in these k distributions implicitly preserves the monochromatic structure of the atmosphere at different pressure levels, thus simulating monochromatic spectral integration at a fraction of the line-by-line computing cost. The k distribution approach also permits accurate modeling of overlapping absorption by different atmospheric gases and accurate treatment of nongray absorption in multiple scattering media. It is shown that the correlated k distribution method is capable of achieving numerical accuracy to within 1 percent of cooling rates obtained with line-by-line calculations throughout the troposphere and most of the stratosphere.
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28 Sep 1998TL;DR: In this paper, the authors propose numerical solutions to partial differential equations and finite-differencing the equations of atmospheric dynamics, including boundary-layer and surface processes, and Radiative energy transfer.
Abstract: Preface Acknowledgements 1. Introduction 2. Atmospheric structure, composition and thermodynamics 3. The continuity and thermodynamic energy equations 4. The momentum equation in Cartesian and spherical coordinates 5. Vertical-coordinate conversions 6. Numerical solutions to partial differential equations 7. Finite-differencing the equations of atmospheric dynamics 8. Boundary-layer and surface processes 9. Radiative energy transfer 10. Gas-phase species, chemical reactions and reaction rates 11. Urban, free-tropospheric and stratospheric chemistry 12. Methods of solving chemical ordinary differential equations 13. Particle components, size distributions and size structures 14. Aerosol emission and nucleation 15. Coagulation 16. Condensation, evaporation, deposition and sublimation 17. Chemical equilibrium and dissolution processes 18. Cloud thermodynamics and dynamics 19. Irreversible aqueous chemistry 20. Sedimentation, dry deposition and air-sea exchange 21. Model design, application and testing Appendix A. Conversions and constants Appendix B. Tables References Index.
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TL;DR: In particular, complex chemistry arising from molecule-rich atmospheres, molecular opacity line lists (sometimes running to 10 billion absorption lines or more), multiple cloud-forming condensates, and disequilibrium chemical processes all combine to create a challenging task for any modeling effort.
Abstract: The atmosphere of a brown dwarf or extrasolar giant planet controls the spectrum of radiation emitted by the object and regulates its cooling over time. Although the study of these atmospheres has been informed by decades of experience modeling stellar and planetary atmospheres, the distinctive characteristics of these objects present unique challenges to forward modeling. In particular, complex chemistry arising from molecule-rich atmospheres, molecular opacity line lists (sometimes running to 10 billion absorption lines or more), multiple cloud-forming condensates, and disequilibrium chemical processes all combine to create a challenging task for any modeling effort. This review describes the process of incorporating these complexities into one-dimensional radiative-convective equilibrium models of substellar objects. We discuss the underlying mathematics as well as the techniques used to model the physics, chemistry, radiative transfer, and other processes relevant to understanding these atmospheres. T...
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Cites background from "Radiative Transfer in Water Clouds ..."
...…would not allow for the treatment of scattering, many k-distribution models will, instead, use the k–g mapping to determine characteristic absorption coefficients for ranges of g (Yamamoto et al. 1970; Lacis & Hansen 1974; Liou 1974; Ackerman et al. 1976; Mlawer et al. 1997), called k-coefficients....
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TL;DR: In this paper, a detailed theoretical study of the radiative properties of water droplet and ice clouds at visible and infra-red wavelengths of 2·3, 3·5, 4·8 and 8·5 and 11 μm is presented.
Abstract: A detailed theoretical study of the radiative properties of water droplet and ice clouds at visible and infra-red wavelengths of 2·3, 3·5, 3·8 and 8·5 and 11 μm is presented. The radiative transfer computations have used a model atmosphere in which the microphysical properties of the clouds have been accurately incorporated. A range of physically realistic size distributions for the cloud particles have been used. The results have been presented in the form of tables of the emissivity, reflectivity and transmissivity, and their equivalent fluxes, at a particular wavelength, as a function of the optical thickness of the cloud layer. A simple scaling relationship enables these extensive tables to be used for any water content of the cloud layers. The results provide a detailed understanding of the radiative properties of terrestrial clouds at thermal infra-red window wavelengths.
The theoretical results are used to interpret infra-red observations of stratocumulus and cirrus clouds.
184 citations