Two stream approximation (radiative transfer)
Encyclopedia
Two-stream approximation of the radiative transfer equation is an approximation of the radiative transfer equation in which radiation is propagating in only two discrete directions.
This approximation captures essence of the radiative transport
in light scattering atmosphere. Two-stream approximation is commonly used in parameterizations of radiative transport in global circulation models
and in weather forecasting models such as WRF
. There is a surprisingly large number of applications of the two-stream approximations, including variants such as Kubelka-Munk approximation. The two-stream approximation is the simplest approximation which can be used to explain common observation inexplicable by single-scattering arguments, such as the brightness and color of the clear sky, the brightness of clouds, the whiteness of a glass of milk, the darkening of sand upon wetting. The two-stream approximation comes in many variants, including Eddington approximation, Modified Eddington, Quadrature, Hemispheric constant models. Modern mathematical description of the two-stream approximation is given in several books.
This approximation captures essence of the radiative transport
Radiative transfer
Radiative transfer is the physical phenomenon of energy transfer in the form of electromagnetic radiation. The propagation of radiation through a medium is affected by absorption, emission and scattering processes. The equation of radiative transfer describes these interactions mathematically...
in light scattering atmosphere. Two-stream approximation is commonly used in parameterizations of radiative transport in global circulation models
Global climate model
A General Circulation Model is a mathematical model of the general circulation of a planetary atmosphere or ocean and based on the Navier–Stokes equations on a rotating sphere with thermodynamic terms for various energy sources . These equations are the basis for complex computer programs commonly...
and in weather forecasting models such as WRF
Weather Research and Forecasting model
The Weather Research and Forecasting model, , is a specific computer program with a dual use for forecasting and research. It was created through a partnership that includes the National Oceanic and Atmospheric Administration , the National Center for Atmospheric Research , and more than 150 other...
. There is a surprisingly large number of applications of the two-stream approximations, including variants such as Kubelka-Munk approximation. The two-stream approximation is the simplest approximation which can be used to explain common observation inexplicable by single-scattering arguments, such as the brightness and color of the clear sky, the brightness of clouds, the whiteness of a glass of milk, the darkening of sand upon wetting. The two-stream approximation comes in many variants, including Eddington approximation, Modified Eddington, Quadrature, Hemispheric constant models. Modern mathematical description of the two-stream approximation is given in several books.