Diffuse_d: Diffuse fraction

In VEZY/DynACof: A Process-Based Model to Study Growth, Yield and Ecosystem Services of Coffee Agroforestry Systems

Description

Compute the daily diffuse fraction from the total daily incident radiation

Usage

Diffuse_d(DOY, RAD, Latitude = 35, type = c("Spitters", "Page", "Gopinathan"))

Arguments

DOY	Day Of Year from 1st January (day)
RAD	Incident total radiation (MJ m-2 d-1)
Latitude	Latitude (deg)
type	Model type, one of Spitters, Page or Gopinathan

Details

The daily extra-terrestrial radiation at a plane parallel to the earth surface (S0_d or H0 depending on the source) is computed following Khorasanizadeh and Mohammadi (2016). The daily diffuse fraction is computed following DB models from :

• Spitters et al. (1986): used in de Bilt in Netherlands, stated that their model is valid for a wide range of climate conditions

• Page (1967) using the data from 10 widely-spread sites in the 40N to 40S latitude belt

• Gopinathan and Soler (1995) from 40 widely distributed locations in the latitude range of 36S to 60N.

Value

Hd/H	Daily diffuse fraction of light (%)

Note

This function force S_0= S_g when S_0= 0 to avoid the production of NA's.

References

• Duffie, J.A. and W.A. Beckman, Solar engineering of thermal processes. 2013: John Wiley & Sons. Gopinathan, K. and A. Soler, Diffuse radiation models and monthly-average, daily, diffuse data for a wide latitude range. Energy, 1995. 20(7): p. 657-667.

• Kalogirou, S.A., Solar energy engineering: processes and systems. 2013: Academic Press. Khorasanizadeh, H. and K. Mohammadi, Diffuse solar radiation on a horizontal surface: Reviewing and categorizing the empirical models. Renewable and Sustainable Energy Reviews, 2016. 53: p. 338-362.

• Liu, B.Y.H. and R.C. Jordan, The interrelationship and characteristic distribution of direct, diffuse and total solar radiation. Solar Energy, 1960. 4(3): p. 1-19.

• Page, J. The estimation of monthly mean values of daily total short wave radiation on vertical and inclined surfaces from sunshine records 40S-40N. in Proceedings of the United Nations Conference on New Sources of Energy: Solar Energy, Wind Power and Geothermal Energy, Rome, Italy. 1967.

• Spitters, C.J.T., H.A.J.M. Toussaint, and J. Goudriaan, Separating the diffuse and direct component of global radiation and its implications for modeling canopy photosynthesis Part I. Components of incoming radiation. Agricultural and Forest Meteorology, 1986. 38(1): p. 217-229.

Examples

# Daily diffuse fraction of january 1st at latitude 35 N, with a RAD of 25 MJ m-2 day-1 :
Diffuse_d(DOY= 1,RAD= 25, Latitude= 35)

VEZY/DynACof documentation built on Feb. 3, 2021, 8:52 p.m.