Irradiance decomposition

ghi_decomposition(
  x,
  yday = "yday",
  GHI = "SWGDN",
  zenith = "zenith",
  beam = "beam",
  method = 0,
  zenith_max = 89,
  keep.all = FALSE,
  verbose = getOption("merra2.verbose")
)

Arguments

x
yday: day of a year, integer vector
GHI: Global Horizontal Irradiance from MERRA-2 subset ( $GHI, W/m^2$ )
zenith: Zenith angle, degrees
beam
method
zenith_max
keep.all
verbose

Details

List or data.frame with estimated following solar geometry variables:

Extraterrestrial irradiance ( $G_e$ )
$G_e = G_{sc}\times\big(1+0.033\cos{(\frac{360n}{365})}\big)$ where:
$G_{sc} = 1360.8W/m^2$ , is the solar constant based on the latest NASA observation (Kopp and Lean, 2011);
$n -$ day of the year.
Clearness index ( $k_t$ )
$k_t = \frac{GHI}{G_e\cos{(zenith)}}$
Diffuse fraction ( $k_d$ )
$k_d = \begin{cases} 1-0.09k_t & & {k_t < 0.22}\newline 0.9511-0.1604k_t+4.388k_t^2-16.638k_t^3+12.336k_t^4 & & {0.22 \leq k_t \leq 0.8}\newline 0.165& & {k_t > 0.8} \end{cases}$
Direct Normal Irradiance ( $DNI, W/m^2$ )
$DNI = \frac{(1-k_d)}{\cos{(zenith)}}\times{GHI}$
Diffuse Horizontal Irradiance ( $DHI, W/m^2$ )
$DHI = k_d\times{GHI}$ where:
$GHI$ - Global Horizontal Irradiance ( $GHI, W/m^2$ ) from MERRA-2 dataset. $GHI = DHI + DNI \times{\cos{(zenith)}}$

Examples

NA
#> [1] NA