scholarly journals Monthly averaged-hourly solar diffuse radiation model for the UK

2014 ◽  
Vol 35 (6) ◽  
pp. 573-584 ◽  
Author(s):  
T Muneer ◽  
S Etxebarria ◽  
EJ Gago
Solar Energy ◽  
2019 ◽  
Vol 193 ◽  
pp. 523-528 ◽  
Author(s):  
J. Appelbaum ◽  
Y. Massalha ◽  
A. Aronescu

1988 ◽  
Author(s):  
R Perez ◽  
R Stewart ◽  
R Seals ◽  
T Guertin

2017 ◽  
Vol 74 ◽  
pp. 616-637 ◽  
Author(s):  
H.D. Kambezidis ◽  
B.E. Psiloglou ◽  
D. Karagiannis ◽  
U.C. Dumka ◽  
D.G. Kaskaoutis

2011 ◽  
Vol 4 (3) ◽  
pp. 1793-1808
Author(s):  
P. Bodin ◽  
O. Franklin

Abstract. The separation of global radiation (Rg) into its direct (Rb) and diffuse constituents (Rd) is important when modeling plant photosynthesis because a high Rd:Rg ratio has been shown to enhance Gross Primary Production (GPP). To include this effect in vegetation models, the plant canopy must be separated into sunlit and shaded leaves, for example using an explicit 3-dimensional ray tracing model. However, because such models are often too intractable and computationally expensive for theoretical or large scale studies simpler sun-shade approaches are often preferred. A widely used and computationally efficient sun-shade model is a model originally developed by Goudriaan (1977) (GOU), which however does not explicitly account for radiation scattering. Here we present a new model based on the GOU model, but which in contrast explicitly simulates radiation scattering by sunlit leaves and the absorption of this radiation by the canopy layers above and below (2-stream approach). Compared to the GOU model our model predicts significantly different profiles of scattered radiation that are in better agreement with measured profiles of downwelling diffuse radiation. With respect to these data our model's performance is equal to a more complex and much slower iterative radiation model while maintaining the simplicity and computational efficiency of the GOU model.


Author(s):  
Alexander L. Brown ◽  
Flint Pierce

The M-1 radiation model is a thermal radiation transport model that is derived from a maximum entropy approximation to the radiative transport equation. It involves the solution of four hyperbolic equations for conservation of radiative energy. The M-1 model has similarities to the classical diffusion approximations (like P-1), but is able to better predict directed flux. Consequently, shadowing and long-range transport can be well resolved for a fraction of the cost of methods with exponentially increasing accuracy costs like the method of discrete ordinates and Monte Carlo ray-tracing. The M-1 method is mostly used historically in astronomical radiation transport, but has recently been shown to work for combustion applications of smaller scale. Past work has shown it to give good comparisons to fire problems with length scales of interest. Because of the potential for the model to predict radiation transport more cost-effectively, it is being examined for implementation as an option in our fire codes. We present the theory behind the model. The Eddington factor is used to partition directed and diffuse radiation. It is normally modeled since it is derived from a transcendental functional relationship. We analyze Eddington factor models presented in previous work, and present a new model that we show to be superior in most ways to all the previously presented models. Some 1-dimensional calculations are also shown that illustrate the potential accuracy and challenges with implementing the M-1 model. Such challenges include the specification of boundary conditions and the development of robust solver methods.


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