A rapidly convergent iterative solution of the non-LTE line radiation transfer problem

1986 ◽  
Vol 35 (6) ◽  
pp. 431-442 ◽  
Author(s):  
Gordon L. Olson ◽  
L.H. Auer ◽  
J. Robert Buchler
Keyword(s):  
Radiation Transfer ◽  
Transfer Problem ◽  
Iterative Solution ◽  
Line Radiation

scholarly journals Radiation Transfer Calculations and Assessment of Global Warming by CO2

2017 ◽  
Vol 2017 ◽  
pp. 1-30 ◽  
Author(s):  
Hermann Harde
Keyword(s):  
Global Warming ◽  
Climate Sensitivity ◽  
Radiative Forcing ◽  
Radiation Transfer ◽  
Climate Model ◽  
Total Solar Irradiance ◽  
Atmospheric Conditions ◽  
Line Radiation ◽  
Long Wave ◽  
Specific Influence

We present detailed line-by-line radiation transfer calculations, which were performed under different atmospheric conditions for the most important greenhouse gases water vapor, carbon dioxide, methane, and ozone. Particularly cloud effects, surface temperature variations, and humidity changes as well as molecular lineshape effects are investigated to examine their specific influence on some basic climatologic parameters like the radiative forcing, the long wave absorptivity, and back-radiation as a function of an increasing CO2 concentration in the atmosphere. These calculations are used to assess the CO2 global warming by means of an advanced two-layer climate model and to disclose some larger discrepancies in calculating the climate sensitivity. Including solar and cloud effects as well as all relevant feedback processes our simulations give an equilibrium climate sensitivity of CS = 0.7°C (temperature increase at doubled CO2) and a solar sensitivity of SS = 0.17°C (at 0.1% increase of the total solar irradiance). Then CO2 contributes 40% and the Sun 60% to global warming over the last century.

scholarly journals Line radiation transfer in non-equilibrium laser plasma

1988 ◽  
Vol 6 (4) ◽  
pp. 703-708
Author(s):  
S. I. Kaśkova ◽  
G. S. Romanov ◽  
K. L. Stepanov
Keyword(s):  
Spectral Line ◽  
Source Function ◽  
Radiation Transfer ◽  
Resonance Scattering ◽  
Plasma Radiation ◽  
Line Profiles ◽  
Radiation Characteristics ◽  
Laser Target ◽  
Line Radiation ◽  
Frequency Redistribution

The self-radiation characteristics of plasma created under the effect of a powerful laser radiation on a target are considered. The radiation in the spectral range from 1 to 1300 Å is calculated in coherent assumption for given gas-dynamic fields corresponding to various phases of laser target explosion. The source function was determined in accordance with a plasma radiation-collision model with the assumption of its transparency. Calculations show that the contribution of line radiation to the total flux may be from 20 to 60%. Mainly, this paper considers radiation transfer. The effect of self-radiation on level populations and frequency redistribution at resonance scattering is taken into account. The resonance scattering is predominant in the coronal plasma. Exit of photons from deeper layers of the target in comparison with the coherent case increases. Macroscopic plasma motion leading to spectral line shift is taken into consideration in the calculations. Output radiation spectral intensity distribution in oxygen and silicon H-like ions resonance lines has been determined. Spectral line profiles calculated with account of basic broadening mechanisms were used.

A Simple Technique to Determine Snow Properties Using Light Reflectance Measurements

2018 ◽  
pp. 27-37
Author(s):  
Alexander A. Kokhanovsky
Keyword(s):  
Radiation Transfer ◽  
Simple Technique ◽  
Transfer Problem ◽  
Imaging Spectroscopy ◽  
Satellite Measurements ◽  
Snow Properties ◽  
Light Reflectance ◽  
Theoretical Foundations ◽  
Reflectance Measurements ◽  
Approximate Equations

In this paper we review theoretical foundations of reflectance spectroscopy of snow. Simple approximate equations are presented, which can be used to calculate snow absorption/extinction coefficients and also snow reflectance. The equations derived could also be used to solve the inverse radiation transfer problem. The technique can be applied to other types of turbid media with large weakly absorbing particles. It has potential for the interpretation both: ground­based and airborne, or satellite, measurements of light reflected from cryosphere of our planet, and also has potential for applications to planetary imaging spectroscopy in general.

scholarly journals Some Problems of Solar Quiescent Prominences in the Light of Ambartsumian’s Ideas

2018 ◽  
pp. 279-290
Author(s):  
A. Nikoghossian
Keyword(s):  
Radiation Transfer ◽  
Temporal Variations ◽  
Line Profiles ◽  
Line Radiation ◽  
Line Intensities ◽  
Different Types ◽  
Physical Features ◽  
Transfer Problems ◽  
Euv Spectrum

The report is a brief overview of our results in the theory of spectral line formation in atmospheres with complex fine structure. The research motivation was due to interpretation of the EUV spectrum of solar quiescent prominences observed with the SUMER spectrograph as a part of the SOHO space program. We describe the methods proposed for solving the line-radiation transfer problems in multicomponent atmospheres which use Ambartsumian's ideas proposed in the theory of radiation transfer and its applications. It is demonstrated that even the simplest static model radiating medium composed of physically different types of elements shows line profiles differing from those formed in the medium with preliminarily averaged properties. The more realistic and complicated case of a multicomponent atmosphere with randomly varying properties is considered with special attention paid to the effect of the velocity field. An important role of the relative mean square deviation of observed line intensities in the diagnostics of physical features of spatial and temporal variations of prominences is shown.

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