Topic
Radiative transfer
About: Radiative transfer is a research topic. Over the lifetime, 43287 publications have been published within this topic receiving 1176539 citations.
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TL;DR: In this paper, inclined magnetic field lines at the boundaries of large-scale convective cells (supergranules) provide "portals" through which low-frequency (5 mHz) acoustic waves, which are believed to provide the dominant source of wave heating of the chromosphere, are used to balance the radiative losses of the ambient solar chromosphere.
Abstract: We show that inclined magnetic field lines at the boundaries of large-scale convective cells (supergranules) provide "portals" through which low-frequency ( 5 mHz) acoustic waves, which are believed to provide the dominant source of wave heating of the chromosphere. This result opens up the possibility that low-frequency magnetoacoustic waves provide a significant source of energy for balancing the radiative losses of the ambient solar chromosphere.
225 citations
TL;DR: In this paper, a mathematical description of light propagation in terms of radiative transfer is developed, and formal solutions of the resulting equation are outlined, but the emphasis is on approximate method of solution, namely the discrete ordinates method, the technique of functional expansion and Monte Carlo simulation.
Abstract: This paper is the first of two reviewing the propagation of electromagnetic radiation of wavelength 0.25–10μm in tissue. After a brief discussion of light/tissue interactions, a mathematical description of light propagation in terms of radiative transfer is developed. Formal solutions of the resulting equation are outlined, but the emphasis is on approximate method of solution—namely the discrete ordinates method, the technique of functional expansion and Monte Carlo simulation. The application of the simplest of these approximate methods, namely the 2-flux and diffusion models, to tissue optics is discussed in some detail. The second paper deals with the optical properties of tissue and the salient characteristics of light fluence distributions in these tissues.
225 citations
TL;DR: In this paper, the authors explore the importance of the composition of airborne mineral aerosols for assessment of their direct radiative forcing at infrared wavelengths and show that the existing variations in refractive places can cause large changes in the major aerosol optical characteristics.
Abstract: We explore the importance of the composition of airborne mineral aerosols for assessments of their direct radiative forcing at infrared wavelengths. Our calculations employing theory and data on spectral refractive indices show that the existing variations in refractive places can cause large changes in the major aerosol optical characteristics. Calculations of IR radiative forcings at the top of the atmosphere and IR downward and upward fluxes, based on an one-dimensional radiation transfer code, give a wide range of results for varying optical models of the mineral aerosols. We estimate that for a "low dust loading" scenario the changes in IR downward flux at the surface relative to dust free conditions are in the range from 7 to 14 W/sq m depending upon the mineral aerosol selected. Under "dry tropics" atmospheric conditions the IR forcing at the top of the atmosphere is in the range from 2 to 7 W/sq m. In turn, for a "high dust loading" scenario the calculated changes, relative to dust free conditions, in IR downward flux at the surface vary from 50 to 80 W/sq m , and the IR forcing at the top of the atmosphere varies from 125 W/sq m. Therefore, we conclude that incorporation of regionally and temporally varying dust mineralogical composition into general circulation models could be beneficial for decreasing the currently large uncertainties in the assessment of radiative forcing by the natural and anthropogenic components of the airborne mineral aerosols. Also the use of appropriate mineralogical data is required for remote sensing of the atmospheric aerosols using satellite infrared observations.
224 citations
TL;DR: The radiative transfer equation in nonemitting media is solved using a four-flux model in the case of Lorenz-Mie scatter centers embedded in a slab because of the nonphenomenological coefficients appearing in the theory.
Abstract: The radiative transfer equation in nonemitting media is solved using a four-flux model in the case of Lorenz-Mie scatter centers embedded in a slab. The various coefficients of absorption and scattering appearing in the theory are nonphenomenological but expressed in terms of quantities available from the Lorenz-Mie framework. Formulas for the various transmittances and reflectances are established. Special cases are then discussed, and (potential or actual) applications reported.
224 citations
TL;DR: In this article, a volumetric radiative loss measurement was made on an argon plasma, correlated with temperature in the range of 10 000 to 26 000°K, and the results were made on the 6965 Ar I line yielding lineshifts, halfwidths, absorption and emission coefficients.
Abstract: Volumetric radiative loss measurements, correlated with temperature in the range of 10 000 to 26 000°K, have been made on an argon plasma. Pressures of 0.5, 1.0, and 2.0 atm have been used. The 1.0‐atm measurements have been corrected for both absorption and ultraviolet emission and the results agree with those of Emmons in the common temperature range. The 6965 Ar I line has also been studied yielding lineshifts, halfwidths, absorption and emission coefficients. The line shift and halfwidth results are below theoretical predictions. Transition probabilities determined from both emission and absorption studies are found to be in reasonable agreement.
224 citations